- Home
- Conferences
- Conference Proceedings
- Conferences
Petroleum Geoscience Conference & Exhibition 2013
- Conference date: 18 Mar 2013 - 19 Mar 2013
- Location: Kuala Lumpur, Malaysia
- Published: 18 March 2013
1 - 100 of 103 results
-
-
Geological Learnings from Lundin’s Five Years of Exploration in Malaysia
By R. JonesLundin Malaysia entered the country in 2008 and since then have acquired 10 3D seismic surveys and drilled ten exploration wells, with a high success rate. The focus areas are in basins generally thought to be marginal, but results show that aggressive and focussed exploration can still yield significant resources. Examples of the geological lessons learned and the prospects tested will be shown.
-
-
-
Potential Use of 4D Seismic To Optimise EOR in A Mature Field, Offshore Sabah, Malaysia
Authors K. Boey, J.A. Harwijanto, C.W. Hong, C. Dinning and J. NguA repeat seismic survey has been planned in 2013 to support and to optimize the EOR field development of a mature, heavy oil field, offshore Sabah using water and ASP injections. This 4D seismic is to repeat the 1996 3D seismic as the base line. The 4D seismic is aimed to detect contact movements after 12 years of production, to identify un-swept parts of the main reservoir, to verify connectivity’s between compartments, to identify gas break-out and to optimize placements of water and ASP injectors. A few studies addressing the 4D signal detectability and survey repeatability have confirmed the feasibility of the project.
-
-
-
Near Surface Modeling and Effect on 4D Repeatability In The Presence Of Shallow Gas Anomalies
Authors A. Sazykin, I. Eckhoff, R. Rashli, P. Smith, G. Nyein, M. Akalin, W. Tang, Y. Widjianto, Z. Dom, A. Ghazali and M. MustafaTime Lapsed 4D seismic surveys are now considered to be an invaluable and essential tool in order to capture, image and analyze valid changes in seismic signal induced by reservoir depletion, or by injection of water or CO2 into the reservoir. 4D monitoring has been proven to be very successful for offshore reservoirs (Haugvaldstad). However, in ultra-shallow water situations, the valid time lapse signal may be obscured with unrepeatable seismic noise, attributable to variations in near surface heterogeneity due to shallow channels with partial gas-saturation, acquisition geometries (e.g. undershoots), strong multiple contamination and ambient noise. These residual unrepeated noises represent the change at the reservoir level and will impact on the quality of the time lapse signal. Currently the best strategy to tackle near surface heterogeneity and other repeatable noises (e.g. multiples) is to repeat source and receiver location as accurately as possible during acquisition. Whilst it is desirable to acquire well repeated surveys, it is not always possible due to limits imposed by operational safety, weather, timing and other factors. Therefore, it is important to create a reliable near surface model and compensate residual differences through robust statistical methods.
-
-
-
Time-Lapse Seismic Data Inversion Constrained by a Fluid-Flow Simulator for Reservoir Monitoring Applications
Authors L. Liang, Neil Hurley, A. Abubakar and T.M. HabashyWe present a fluid-flow constrained inversion approach for joint interpretation of time-lapse seismic data and production data. In this approach, the full-waveform seismic inversion is integrated into the conventional history matching process. Therefore, the interpretation of time-lapse seismic data is constrained by the fluid flow simulation in the reservoir, and it automatically takes into account both saturation and pressure effects. We use a synthetic crosswell example to demonstrate the advantage of this approach.
-
-
-
The Maharaja-Lela 2010 Exploration Campaign: The Key Opener for an Additional Development
More LessThe Maharaja Lela Jamalulalam field (MLJ), located 50km offshore Brunei, was discovered in 1990 and has been producing oil, gas and condensates since 1999. It is constituted of a series of faulted panels where the hydrocarbons are trapped in two or three way closures against normal faults. The reservoirs are good quality shoreface sands. A new exploration campaign, targeting undrilled down-dip panels, started in 2004 with a new seismic acquisition. Following processing and interpretation, several successful exploration wells were drilled. In 2010, Total drilled the deepest well in Brunei, reaching its TD at nearly 5700m. In spite of the high pressures and temperatures (over 1100 bars 65 degrees Celcius), the proven gas columns are high, while the reservoir properties are preserved by overpressures. This very successful exploration campaign has enabled the Bloc B JV Partnership to identify sufficient resources to start an incremental development project of the MLJ Field and to extend Gas Deliveries to Brunei LNG plant. It also opened up additional exploration opportunities.
-
-
-
Significant Hydrocarbon Accumulation in Deep Overpressured Play of West Baram Delta: A Breakthrough
Authors Mh Hafizan Wahab, A. Asraff, J. Juhari Ismail and C. Anwwar IbrahimTwo recent HPHT wells have successfully tested the deep seating overpressured playtype in West Baram Delta with significant discoveries of gas and condensate at depths of more than 4500m below mudline. The well recorded the highest reservoir pressure to date in Malaysia, approximately 14,000 psi approaching the operational limit of the Blow Out Preventer (BOP) used. Total of 200m nett gas sand were penetrated with all gas bearing reservoirs are filled with hydrocarbon to the structural spill (with average of 650m of vertical gas column), proudly standing as the longest clastic section ever drilled in the West Baram Delta province. The structure which was filled to spill is primarily, but not exclusively attributed to an excellent lateral seal of a growth fault system. This is further enhanced with the deposition of foreset shales on the hanging wall of the fault.Overpressure condition has also revealed the upside potential of the reservoir characteristics, i.e. significant improvement in the porosity preservation below overpressure zones, resulted to better producibility of the gas bearing reservoir. Understanding the play type behavior remains the critical challenge particularly in evaluating the structuration, trap integrity, and the seal capacity.
-
-
-
The Awakened Giants
Authors Nur Fadzlinda Mohamad Khazali, S. Osman and C.S. AbdullahFEW PINNACLES WITH SEISMIC EXPRESSIONS PRESUMABLY ENHANCING THE 'BLOWN TRAP'FEATURES ARE PUT FORWARD. SIGNIFICANT CIRCULAR FAULT FRAMEWORKS IN THE OVERLYING OVERBURDEN SEQUENCE COMPLETE WITH A 'SEISMIC PLUME' EMANATING FROM THE PINNACLES CRESTS STRENGTHENED THE FAILED TRAP BELIEF. EARLY ASSESSMENT OF THE PINACLES WITH THE SIMILAR SEISMIC FEATURES LED TO DOWNGRADING OF THEIR HYDROCARBON TRAPPING POTENTIAL. THE UNDERSTANDING TRIGGERED TOTAL PETROLEUM SYSTEM RE-EVALUATION OF THE CARBONATE PINNACLES IN THE REGION. SINCE 2004, MORE THAN 15 PINNACLES WERE TESTED AND PROVING 18 TRILLION CUBIC FEET GIIP IN TOTAL, ACHIEVING AN EXPLORATION SUCCESS RATIO OF HIGHER THAN 80%.
-
-
-
First Broadband Circular Shooting Survey in Malaysia: Integrating Survey Design and Modeling for Simultaneous Deployment
Authors S.K. Chandola, T. Velayatham, M. Tham, K. Hong Ho, L. Cheng Foo, N. Mahmud, S. Kumar and L. Chung TeckThe quality of the surface seismic imaged data depends on many factors. The images can be very poor if the survey is located in an area characterized by complex overburden and structural setting. In addition, the conventional data acquisition and processing methods may not be adequate to address the challenges posed by the subsurface geology and geophysical complexities. The integrated approach of survey design and modelling, unique acquisition technique, advance data processing workflows can help address these challenges. The case study presented here is one of the first to seamlessly deploy two of the most cutting edge acquisition technologies at the same time: i) circular shooting technique for extending the azimuth sampling and concurrently ii) constant gradient slant cable towing technique, whereby the streamer depths are shallow at the front and deep at the back to exploit the diversity in streamer notches to extend the bandwidth sampling. By doing so, it not only eliminates the need to acquire the survey twice but also enables one to realise the benefits offered by both technologies simultaneously.
-
-
-
Variable Depth Streamer Acquisition – Benefits for Rock Property Inversion
Authors L. Michel Sdn Bhd, R. Hanumantha Sdn Bhd and F. Baillard Sdn BhdQuantitative interpretation teams face two challenges when using model-based inversion: to extract meaningful wavelets and to build accurate low frequency models. The use of variable depth streamer gives access to lower frequency and enable to use calibrated seismic velocities as an initial model. With constant depth streamer and sparse well-log, the well-derived low frequency model may be inaccurate and cause biased inversion results. Seismic data acquired using variable depth streamers are ideally suited for inversion as they provide directly the missing low frequencies, hence removing the need to build low frequency models from well data. In order to quantify the impact of the low frequency content on seismic inversion, comparative elastic inversion tests have been conducted using 2-D seismic data from Constant Depth Streamer (CDS) and Variable Depth Streamer (VDS) acquisitions using the exact same streamer geometry. Both datasets from offshore NW Australia were acquired simultaneously, with a constant streamer depth of 7m for the conventional acquisition and streamers’ depth ranging from 7.5 to 58 m for the VDS acquisition.
-
-
-
Autonomous Nodal Marine Seismic Technology
Authors C.D.T. Walker and G.R. ArringtonBy eliminating the traditional sources of technical downtime in Ocean Bottom Cable (OBC) system, autonomous seismic nodes can deliver higher productivity and hence more cost effective ocean bottom data acquisition. HSE exposure and risk is reduced through the removal of a recording platform - either a recorder vessel or 2 ton recording buoys - in combination with the automation of the node handling system on the back deck of the vessel. Data quality is superior to that acquired with digital accelerometers since the noise floor of the omni-directional geophones used is substantially lower, especially at low frequencies, than that of the digital sensors commonly used in present day OBC systems.
-
-
-
Comprehensive Geological and Geomechanical Fractured Basement Characterization and Modelling; Integrated Multidisciplinary Approach Using New Techniques
Authors R. Dashti, N. Pendkar, M.L. Lee, S. Marca and M. JohanssonIn this work, borehole image and sonic data from a highly deviated borehole were integrated with outcrop studies to characterize natural fractures and develop a 3D fracture network. Then geomechanical analysis was performed to determine the stress regime and magnitude around the wellbore which was then incorporated into the study to define the critically stressed fractures which are most prone to production as well as breakthrough.
-
-
-
The Petroleum Systems of Onshore West Baram Delta, Northern Sarawak, Malaysia
Authors John Jong, P. Barber, L.H. Chim, Q.T. Tran, H. Kusaka, K. Muramoto and R. UchimuraA sequence stratigraphic investigation of the onshore Baram Delta integrated with modern biostratigraphic analysis suggests that the sedimentary section in SK333 has been affected by three major tectonic episodes of deformation:(i) Late Cretaceous to Eocene (79.5-36Ma) block faulting, (ii) Late Oligocene to Mid Miocene (30-20.5Ma) wrench movement and related folding followed by (iii) Mid Pliocene to Recent (4.0-0Ma) uplift and compressional folding. Subsequently, two optimum play trends have been mapped in SK333. These are the Miri–Asam Paya-Seria (MAS) and Engkabang Anticlinoria trend respectively, which are separated by the Badas Synclinorium, an abundant source kitchen area. To summarise the plays: The MAS Anticlinoria trend is an enhanced oil fairway with prolific oil charge from Late Miocene coals and peats on a confirmed oil migration fairway from the Badas Syncline. Reservoirs are excellent quality Mid Miocene to Early Pliocene shoreface-shelfal sands with deeper turbidite sand upside. The Engkabang Anticlinoria is mainly a deep tight gas play with inferred charge from overmature Eo-Oligocene basinal shales. This play is higher risk than the Miri Trend due to the potentially former depth of burial of the Eocene carbonate reservoir objective to approximately 5-6kms. This is inferred to have led to diagenetic inhibition of porosity.
-
-
-
Subseismic Scale Fracture Characterization Combining Geomechanics and Tectonic History
Authors M. Lefranc, A. Dubois, J.P. Joonnekindt and L. MaertenThe 3D seismic data in fractured basement reservoirs can sometimes be challenging to interpret and allow identifying only the main faults affecting the naturally fractured reservoirs. Moreover, natural small-scale fractures are known to be capable of significantly altering the flow of hydrocarbons and are below the resolution of the seismic data in this type of environment. In order to palliate seismic data quality in these reservoirs and to obtain 3D properties related to fracture orientation and density at a subseismic scale, a geomechanics-based methodology has been developed. This methodology is based on the geomechanical properties of the rock, 3D fault geometry, and far-field stress associated with each tectonic event. The resulting properties can be combined with well log data and seismic attributes to condition a discrete fracture network model and predict the fracture porosity and permeability in challenging environments, like fractured basement reservoirs in SE Asia. It also provides robust fracture orientation distributions, which improve considerably the quality of the models in exploration fields where limited number of wells exists.
-
-
-
Exploring a New Characterization, Modeling and Simulation Workflow for Vietnamese Basement Reservoirs
Authors T. Doan, C. Milliotte, S. Matthäi and L. PhuocHydrocarbon reservoirs offshore Vietnam are unique in that they are produced from structurally elevated igneous rocks that form faulted basement blocks on top of which the Cretaceous to Tertiary siliciclastic sediments were deposited to provide the source rocks of the oil. This paper explores how to construct, parameterize and simulate geologically realistic – albeit heuristic – models of basement and surrounding sediments in Vietnamese basement reservoir to gain answers to the following questions: How can we represent these structurally complex reservoirs in simulation models? Which new approaches can help property modeling? What are the typical drainage areas of wells drilled into basement faults? How much fluid do these produce from within the basement versus the surrounding sediments? How does flow rate affect ultimate recovery?
-
-
-
Developing the Largest Carbonate Oil Field in SE Asia – Banyu Urip, Cepu Block
Authors F.W. Musgrove and M. SunMobil Cepu Ltd and partners in the Cepu KKS, East Java basin plan to start development drilling of the Banyu Urip field in 2012 with a targeted startup in 2014. This is a very important development for Indonesia to maintain the Indonesian national production target as this field will produce 165k BOPD initially. The Banyu Urip field was discovered in 2001 and has been certified by ITB with more than 1 Billion BBL in place making it the largest onshore oil discovery in Indonesia in the last several decades. Banyu Urip is a high relief Oligo-Miocene carbonate isolated platform onshore at approximately 4000 feet TVDSS. 30 producers will be required to meet the initial target (5500 BOPD ave per well). 13 water injectors will be required to meet aquifer pressure maintenance target. This paper will describe the field and development concept. The Banyu Urip Field is an isolated platform that rises almost 3000 feet from the surrounding carbonate platform. The platform is made up of repeated 150 foot thick cycles of shallow water carbonate that has been exposed to fresh water repeatedly and leached to form high quality reservoir rock with average 26% porosity and 100 mD permeability in the interior.
-
-
-
The Rivers of Luconia: The Effects of Sea-Level Lowstands on the Stratigraphy of a Mixed Carbonate/Clastic Province; Miocene-Present, Offshore Sarawak, NW Borneo
By E. KosaCentral Luconia is a gas-producing carbonate province offshore Sarawak, NW Borneo, with some 250 carbonate build-ups, now mostly covered by clastics. Historically, these clastics have been interpreted as open-marine, pro-delta sediments deposited over drowned carbonates. Sequence-stratigraphic frameworks have been based on subdivision of the stratigraphy into regressive cycles punctuated by flooding surfaces. Recent studies have lead to re-interpretation of these strata as stacked delta lobes separated by sequence boundaries as well as by flooding surfaces, with palaeo-coastlines extending basinward of most contemporaneous build-ups. Carbonate build-ups are interpreted to have been periodically engulfed by clastics and land-locked during sea-level lowstands. Palaeo-rivers would consequently be expected to flow over the exposed shelves during forced regressions, producing erosional geomorphology at sequence boundaries. Shallow-marine, paralic and fluvial sediments would be expected in the uppermost parts of the stacked shelf units, which are indeed characterised by distinct upward-cleaning trends. This study documents evidence for fluvial and other erosional geomorphology and links this to hydrocarbon habitats, carbonate-clastic interactions and reservoir/seal distribution. Fluvial processes are shown to have exerted major control on carbonate inception in the Middle Miocene, as well as on hydrocarbon-retention capacity of the clastic overburden following later carbonate demise and burial.
-
-
-
Diagenesis of the Central Luconia Carbonates: The Roles of Methane-Derived and High Temperature Fluids in Controlling Reservoir Properties
By M.Y. AliThis paper presents the results of a comprehensive diagenetic study and cementation history of the Central Luconia carbonates based on integration of petrography, SEM/BSEM, XRD, cathodoluminescence, electron microprobe, stable carbon, oxygen and sulfur isotopes, fluid inclusion microthermometry and absolute dating using strontium isotope technique.
-
-
-
The Lower Miocene Great Barrier Reef of Sarawak, Malaysia: The Exploration Potential of Cycle II and III Carbonates
Authors E.W. Adams, P.F.M. Janssen, S. Ghani, S.J. Gough and P. WinefieldA play-based exploration (PBE) study carried out in Shell assessed the remaining exploration potential of onshore and offshore Sarawak and enabled identification of sweetspots in previously overlooked plays, the definition of an internally consistent new lead portfolio, and the addition of a ranked list of coveted acreage (Gough et al., 2012). Furthermore, using PBE workflows, a framework was established connecting the evolution of tectonic regimes and basin fill with carbonate occurrences and growth styles since the Late Eocene and provided the basis for a play-based assessment of the remaining exploration potential of carbonate plays in Sarawak (Adams et al., 2012). The main carbonate play in Sarawak are the well known and intensively studied Middle Miocene to Pliocene Luconia Province carbonates. However, the above mentioned regional PBE study refocused Lower Miocene carbonates which in eastern Sarawak developed extensively. Both onshore and offshore, these ‘older’ carbonates have been penetrated by several wells including recent high profile discoveries. This paper puts forward the stratigraphic, tectonic, and age context of these Lower Miocene carbonates and examines the variability in carbonate deposition on the Sarawak Shelf. Finally, the remaining exploration potential is discussed by comparing and contrasting northern Central Luconia with south-eastern and onshore Sarawak.
-
-
-
Determining the Source of Low Level H2S Using Novel Sampling Techniques
Authors D.E. McKinney, H.L. Albrecht and B. OkohAs operators drill deeper into higher pressures and temperatures as well as begin exploiting resource plays such as gas shale and liquid rich shale, the concentrations of gas contaminants such as H2S and CO2 become more and more important, especially in prescribed low cost developments. To understand the source of H2S, sulphur isotope mapping of pyrite, organic sulphur, anhydrite and H2S is crucial. This paper discusses a case study of a discovered field where low level H2S (25-40 ppm) is present in the hydrocarbon accumulation. Proper planning and novel techniques for the sampling of the reservoir fluid, preservation of the H2S and analysis of the Sulphur-34 values for H2S are described along with the business impact of the results.
-
-
-
Novel Chemical Tracers For Determining Residual Saturation
Authors M. Myers, C. White, L. Stalker, B. Pejcic and A. RossAlkyl monoester tracers (e.g. ethyl acetate) have previously been used in a single well chemical tracer test to determine residual oil saturation. We propose here to use diesters (e.g. propylene glycol diacetate) and triesters (e.g. triacetin) for determining residual oil saturation and residual carbon dioxide saturation. These tracers have a much lower flash point making them much safer and potentially expanding their application. Compared to the monoester tracers, the proposed tracers have similar reactivity, partition coefficients and water solubility. We have recently tested these tracers in the field to determine residual carbon dioxide saturation and obtained tracer breakthrough profiles suitable for analysis using computer simulations.
-
-
-
Petroleum Source Rock Properties of Surma Group Shales of Bengal Basin, Bangladesh
Authors Md. Farhaduzzaman, W. Hasiah Abdullah and M. Aminul IslamBangladesh (a major part of Bengal Basin) is situated at the northeastern corner of Indian subcontinent and it is extending to the Bay of Bengal. In this present paper, the hydrocarbon source rock properties have been discussed on the basis of the organic geochemical and petrological methods. A total of eight shale core samples were collected from eight different wells of respecting eight gas fields covering the entire Deep Basin, the most important tectonic unit of Bengal Basin. All of the shale samples were chosen from the Surma Group. The samples have been crushed to fine powder and subsequently analyzed using Source Rock Analyzer-SRA (i.e., Rock-Eval equivalent). The Soxhlet’s equipment was used for extracting EOM which were subsequently fractionated into aliphatic, aromatic and NSO. The polished blocks were used for petrographic analysis using a Leica CTR 6000-M microscope with white and ultraviolet (UV) light sources. The extracted organic matter of the investigated shale samples is mainly Type III together with minor contribution of Type II kerogen as indicated by the SRA and petrographic data. The hydrocarbon source potential has been deduced as poor to good quality. The studied Surma Group shales represent an immature to early mature oil window.
-
-
-
Prospectivity and Source Rock Generative Potential of the Red Sea Basin, Sudan
Authors Y. Hadad and W.H. AbdullahThe Red Sea rift marks the break-up of the Afro-Arabian plate in the Eocene-Oligocene time. Generally, fluvio-deltaic and marginal to fully marine sediments were deposited, good reservoir quality and potential source rocks are present. To date, the Sudanese Red Sea, like the Red Sea as whole, represents a grossly under-explored petroliferous basin. The pre-Salt Rudeis-Kareem shales are expected to be a good petroleum source rock for the basin. Moreover, Shales of base Zeit (post-Salt) are considered the main source of the known accumulated hydrocarbon (gas and condensate) in the shallow targets. The measured amount of TOC, HI, and hydrocarbon expelled from pyrolysis of kerogen of the examined samples indicates the source rock generative potential of these intervals. The salt tectonic challenging exploration activities and control the hydrocarbon entrapment as well the Salt movement is recent as the recent sediments been deposited and conslidated. In this study,1D and 2D petroleum system modeling has shown that the two source bed are thermally mature for hydrocarbon generation with Rudies Formation exceeded oil window and all its potential transformed to hydrocarbon.
-
-
-
Finding New Oil Accumulations in a Mature Basin: Exploration Strategy In The East Balingian Basin - Offshore Sarawak
Authors Teguh Prasetyo and Mohd Khalid JamiranDescribe the Petroleum System components and the strategy to find new oil accumulations in the East Balingian Province
-
-
-
Low Frequency Modelling for Seismic Inversion
By M. SamsLow frequency models are required for seismic inversion. Low frequencies are beneficial in that they introduce absolute values, gradual changes, improved resolution, but are potentially biased. Removal of the potentially biased low frequency component to yield relative results can introduce artefacts that make interpretation complicated. Building accurate low frequency models is complicated. A number of different techniques have been introduced over the years to help improve the efficiency and accuracy of construction, which rely on an understanding of the local geology and rock physics. Despite these innovations there remain limitations that cannot be easily overcome.
-
-
-
Leads and Prospect Delineation Using Rock Fluid Index with Case Example from Clastic Sediment PM330
Authors H. Mohamed and R. DanialThe demand for seismic inversion study in exploration phase is now growing as more case studies have successfully demonstrated the benefits of inversion results to delineate leads and prospects within a specific reservoir and same seismic data set. A recent 3D Simultaneous AVO Inversion study was carried out to delineate leads and prospects from two different overlapping seismic surveys and at different stratigraphic levels. By performing additional processes from the standard inversion workflow, a consistent and correlatable elastic property from multiple seismic surveys with different seismic vintages has been achieved. Quantitative Interpretation Analysis for both surveys at different target levels was carried out by building a Rock Fluid Index (RFI) from the calibration wells. RFI is an index calculated from a background line separating Sand and Shale in the P-Impedance and Vp/Vs domain. The RFI index has removed the compaction trend and made lithology and fluid interpretation easier for leads and prospect delineation.
-
-
-
Elastic Inversion for Better Lithology and Porefill Discrimination
Authors M. Hermana and D.P. GhoshSeismic inversion for acoustic impedance has been widely practiced in the oil industry and PETRONAS is no exception. However, in order to relate seismic amplitudes to geology, i.e. to lithology and/ or pore fill, it is required to understand all physical factors that influence seismic amplitudes in one way or the other. However, it is possible for us to have success in amplitude study by the study of seismic in Elastic domain. This paper discusses the elastic inversion method and application for lithology and porefill discrimination and challenge in Malay Basin field. The results showing that in the elastic domain, porefill can be discriminated from lithology either in Acoustic Impedance-Shear Impedance domain, Acoustic Impedance-Poisson ratio domain or Shear Impedance-Poisson ratio domain. Elastic inversion into Poisson ratio domain can be used to delineate Gas zone in Malay Basin field.
-
-
-
The Feasibility of Qp/Qs as Hydrocarbon Indicator in Malay Basin Field
Authors D.P. Ghosh, M. Hermana, Z.Z. Tuan Harith and C.W. SumThe challenging in seismic exploration is how to separate pore fluid from lithological effect for better hydrocarbon prospecting. Many seismic attribute have been proposed such as fluid factor, orthogonal Lame Constant, Poisson ratio and AVO rotation and others. All of them are more based on elastic properties. This paper discuss the feasibility of other rock properties (Qp/Qs ) which is more based on attenuation mechanism of seismic wave for hydrocarbon prediction. The result showing that based on well logs study, the Qp/Qs on Malay Basin Filed has potential to be used as hydrocarbon indicator. This parameter curve is well agreement with water saturation curve. The contrast between gas sand and shale is highest than lamda over mu and Poisson ratio parameter for all condition; high and low acoustic impedance contrast. Unlike in lamda over mu and Poisson ratio curve, there is no trend on Qp/Qs curves as well as in water saturation curve. Hence we conclude that the ability of Qp/Qs parameter in determining the hydrocarbon is better than lamda over mu and Poisson ratio.
-
-
-
Mitigation of the 3D Cross-Line Acquisition Footprint Using Separated Wavefield Imaging of Dual-Sensor Streamer Seismic
Authors A.S. Long, R. Jones, Y.A. Chim, M. Tang, H. LeGleut, S. Lu, D. Whitmore, A. Betteridge and M. FaroukiLundin Malaysia BV completed the first-ever application of separated wavefield PSDM imaging to 3D dual-sensor streamer seismic data acquired over the PM307 Block as a test to improve shallow geological interpretation. The methodology exploits the illumination corresponding to surface multiple energy, and thus exploits what has historically been treated by the seismic industry as unwanted noise. Whereas a strong cross-line acquisition footprint affected the very shallow 3D data using conventional processing and imaging, the new results yield spectacular continuous high resolution seismic images, even up to and including the water bottom. One implication of these results is that very wide-tow survey efficiency can be achieved without compromising shallow data quality if dual-sensor streamer acquisition and processing is used, even in very shallow water areas such as that discussed here. The imaging methodology can account for all degrees of lateral variability in the velocity model, full anisotropy can be accounted for, and angle gathers can be created to assist with velocity model building.
-
-
-
Depth Velocity Model Building beyond Reflection Tomography, a Case Study Offshore Vietnam
Authors N. El Kady, Y. Guo, A. Nahar, Z.M. Dom and J. ZhouIn the Southeast Asia offshore exploration, shallow reefs and channels, widely spread volcanic rocks and basement fracture system are some of the major challenges in seismic imaging. However, conventional reflection tomography has hard time to provide accurate and high resolution model to solve these challenges and other model building techniques are needed to introduce those velocity anomalies. First, reflection tomography has limited resolution at shallow (50-400m) because of limited number of offsets. So geo-mechanical modeling is used to put fast and slow velocity of reefs and channels. Second, the intrusive and extrusive volcanic rocks are too thin (around 50m-100m) to be resolved by tomography. Reflectivity inversion is used to derive the high resolution velocity of the volcanic rocks. Third, TTI/HTI anisotropy is used to simulate the situation, that image velocity is always much slower than well sonic velocity inside basement, and improve the image. Overall, geo-mechanical modeling, reflectivity inversion and TTI/HTI modeling in basement, together with the conventional reflection tomography, generate high resolution velocity model for PSDM thus provide much needed imaging uplift.
-
-
-
Hydrodynamics – A New Class of Reservoirs?
Authors R.E. Swarbrick, S.A. O‘Connor and S. GreenSince the 1950’s, active reservoirs/aquifer have been recognized, and associated with fluid recharge from upland areas, driven by hydraulic head. In recent years, hydrodynamics has also become recognized as being associated with highly-overpressure shales in the deep parts of basins, where reservoirs provide a drainage path to the subsurface. These so-called laterally draining reservoirs appear to be a newly recognized class of reservoirs in many basins around the world, including many deep water areas. Laterally draining reservoirs are characterized by systematic overpressure differences that aid fluid migration, in addition to buoyancy effects. These reservoirs provide more effective vertical barriers to fluid flow, and more effective hydrocarbon seals, as well as the potential for long hydrocarbon columns, due to increased pressure differences across seals. Many examples of laterally draining reservoirs can be demonstrated from SE Asia basins, including the Malay Basin and Gulf of Thailand. Confidence is increased when a robust model for shale prediction can be accompanied by direct pressures measured in the interbedded reservoirs. Identification of laterally draining reservoirs presents new exploration opportunities for hydrodynamic traps.
-
-
-
Multi-Azimuth PSDM Processing in the Presence of Orthorhombic Anisotropy - A Case History Offshore North West Australia
Authors S. Birdus, J. Sun, W. Sun, Y. Xie, M. Gazzoli, M. Andreolli and A. UrsulicIn this paper we present a case history of multi-azimuth 3D PSDM processing. The datasets show strong HTI as well as VTI anisotropy. We show the processing workflow with emphasis on the construction of an imaging velocity model that correctly represents the orthorhombic anisotropy and short-wavelength velocity variations. The PSDM image is improved over earlier processings.
-
-
-
Adaptive Curvelet Domain Primary-Multiple Separation
More LessWe describe the implementation of using curvelet domain for separating multiples from primary events in seismic data and subsequently removing the multiples from noisy seismic data. Introduced by the sparsity of curvelet coefficients of seismic data, an optimization problem was formularized by incorporating L1- and L2-norms, which is then iteratively solved. We show that our approach gives superior performance than the conventional least-square separation method in attenuating multiples and incoherent noise, and with better preservation of primary events. Moreover, our particular strategy in globally adapting the model widens the scope of application of this method for multiple models predicted from various methods. We demonstrate the application of our approach on synthetic and field data examples.
-
-
-
Concentric Saturation Maps for Carbonate Heterogeneity at the Wellbore Scale
Authors C.J. Maeso, S.N.F.B. Zulkipli and P. ArtaThe carbonates of the Pinnacle Reefs offshore Malaysia are known to be a complex mixture of depositional and diagenetic fabrics. Information on these fabrics is sometimes sparse due to limited borehole logging as a result of partial or total losses. A technique has been developed to help quantify the radial variations by using azimuthal LWD measurements. The combination of multi-directional density and resistivity measurements (the latter also at multiple depths of investigation) allows concentric heterogeneity maps to be built at each depth level. These are based on saturation by combining the azimuthal density porosity and resistivity measurements. In the three wells analysed, distinct variations in heterogeneity are observed around and along the boreholes. In places these can be directly related to local dolomitisation.
-
-
-
Archie’s Parameters Determination Techniques in Carbonate Reservoirs: New Technique for More Accurate Parameters
By G.M. HamadaThe main objective of this study was to measure Archie's parameters on 29 natural carbonate core plugs at reservoir conditions, using live oil, these core samples were taken from three wells. For this purpose three techniques were implemented to determine Archie’s parameters; conventional technique, core Archie's parameters estimate (CAPE) technique and three dimension (3-D) technique. Water saturation profiles were generated using the different Archie parameters determined by the three techniques. These profiles have shown a significant difference in water saturation values. Such difference could be mainly attributed to the uncertainty level for the calculated Archie parameters. These results highlight the importance of having accurate core analysis's measurements performed on core samples that yield representative a, m and n values that highly influence the water saturation values.
-
-
-
Application of Pulse Neutron Logging to Determine Residual Oil Saturation in a Mature West Texas Carbonate Field Under
More LessFor the past several years, carbon dioxide (CO2) has been injected into the gas cap of a mature West Texas carbonate field to enhance the current recovery mechanism of gravity drainage. A key uncertainty in the process is quantification of residual oil saturation (ROS). Understanding both the volume and vertical profile of the ROS in the reservoir will lead to an effective placement of CO2 in the gas cap. A number of saturation logging options exist today for the purpose of measuring ROS in either a cased-hole or an open-hole environment. This paper examines the application of a couple of cased-hole pulsed neutron logging tools used to measure ROS across a gas cap and on into a residual oil zone (ROZ).
-
-
-
Applications and Challenges of Pulsed Neutron Capture and Carbon/Oxygen Logging for Infill Drilling Opportunities in Mature Malay Basin Field
More LessThis poster presents the application of the pulsed neutron capture and carbon/oxygen logs in identifying remaining hydrocarbon saturation for infill drilling opportunities in a mature Malay basin field located in offshore Malaysia. Key challenges faced during data acquisition and analysis under complex borehole and reservoir environment settings are discussed. These challenges include the small capture cross section contrast between oil and water when traversing an oil-water contact and the reduced dynamic range of the carbon/oxygen ratio response in larger completions. A brief review of the tool measurement principles, operational considerations and limitations, interpretation principles, and integration of engineering and geological data will also be presented together with several key learnings from the case studies.
-
-
-
Broadband Marine Seismic, Does Acquisition Make a Difference?
Authors M.P. Bayly, S.K. Chandola, C.F. Low, A.A. Muhamad and S.L. NgExpanding the bandwidth of surface seismic data, particularly towards low frequencies, is essential for many exploration and production objectives. Broader band signals, both in land and marine environments have marked benefits for imaging deeper targets, imaging through absorptive overburdens, and especially inversion for rock properties. Various methods have been proposed and implemented to expand seismic bandwidth; these include both acquisition and signal processing methods. A question that is often asked is how much difference does changing the acquisition geometry make? In this paper, we present a case study of a consistent, experimental offshore dataset in Southeast Asia. This data consists of a single boat pass of four different cable depth configurations. These data were then processed with their appropriate deghosting methods and results compared. In addition, we examine methods for evaluating the success of these methods and their potential pitfalls.
-
-
-
The Value of Broadband Seismic For the Interpreter and Reservoir Geophysics
Authors M.T. Farouki, C. Reiser and T. BirdThe seismic industry is constantly seeking ways of improving the contribution of seismic data to the upstream E&P workflow from seismic acquisition to reservoir modeling. We review recent developments in broadband seismic and illustrate how these benefit seismic interpreters and geoscientists involved in reservoir characterization or quantitative interpretation projects. Petroleum Geo-Services (PGS) launched in 2007 a dual-sensor streamer acquisition system developed with the objective of providing broader seismic frequency bandwidth without any compromise in pre-stack data quality or acquisition efficiency. Results over the last five years have demonstrated the benefits of this system in processing, seismic interpretation and reservoir geophysics. Case studies from different geological settings illustrate the benefits to end-user practitioners in seismic interpretation and seismic reservoir characterization across a range of E&P asset development phases from exploration to appraisal and field development/optimization.
-
-
-
Processing Variable Depth Streamer Data: A Case Study from offshore Sarawak-Malaysia
Variable depth tow streamer acquisition coupled with proprietary processing technology to record and retain high bandwidth seismic data enables improved imaging of subsurface structures.
-
-
-
The Value of Regional Correlation and Analogues in Managing a Mature Asset: Examples from the Central Luconia Gas Fields
Authors G.M.D. Warrlich, E.W. Adams, T.C.F. Tam, E. Kosa, K.K. Ting and A.D. KayesFor Petroleum Geoscientists adequate use of analogues and sound methods of extrapolating properties to an exploration target or producing field are key tools to reduce subsurface uncertainties and improve prediction of overburden and reservoir behavior. An effective use of regional analogues is achieved by setting up a common correlation framework of a particular geological province, based on sequence stratigraphic principles. In addition, ancient outcrop and modern-day depositional analogues are used to improve the understanding of large-scale heterogeneities and reduce uncertainties in reservoir properties and flow behavior at the inter-well scale. This paper shows examples of applications of this methodology to the Central Luconia Gas fields: 1. Gas recovery factors depend on presence or absence of argillaceous tight layers formed during flooding events in a reservoir.Predicting these layers in platforms with limited core is possible through a sequence stratigraphic framework. This helps planning development wells and forecasting water-cut development. 2. In addition to subsurface data, ancient outcrop and modern-day depositional analogues are used in the Luconia gas reservoirs to improve prediction of reservoir properties away from well penetrations and help convert 3D seismic data into reservoir properties. Improved forecasting from these models enables integrated planning and facilitates asset management decision making.
-
-
-
Approaching a Parity between Welltest and Wireline-Driven Average Permeability For Carbonates
Authors A H Asari Ramli and M.R. Michael Mehmet AltunbayDisparities between wireline-driven permeability profiles and averages for carbonates versus DST/well test permeability averages or core permeability values have been a major source of errors in petrophysical and engineering calculations that require permeability input. We have devised a methodology to lessen and eventually to eliminate these errors by deriving more representative permeability profiles and averages for any given interval of carbonate rock to be used in static and dynamic modeling/simulations. Most permeability averaging techniques are devised with the concept on intergranular permeability being at the center of assumptions, hence appropriately leading to major deficiencies and errors permeability comparisons in carbonates. Hence, we would like to look at the permeability types in carbonates that can be identified via wireline logs to devise our methodology. Carbonate permeability types that can be sensed and identified via wireline are summarized below as: 1.Matrix permeability (attainable from NMR) 2.Contributions from “vug permeability” as a function of degree of connectedness of vugs (modification of matrix permeability via acoustic-driven connectivity factor) 3.Fracture permeability (empirical obtained via image log driven width/aperture) 4.Welltest permeability Correct averaging of calibrated wireline permeability enhances the accuracy of static and dynamic modeling efforts and better the history matching results.
-
-
-
Mass Transport Complex (MTC)-Controlled Sand Deposition: A Case Study from Offshore Brunei
Authors H. Maulana, A.F. Bakar, H.S. Hakimi, M.F. Rasli, H. Ariffin and M.A. IsmailMass transport complexes (MTCs) are one of the major geologic features observed in many deepwater provinces. MTCs commonly occur in the slope and basin floor settings and are broadly characterised based on their internal characteristics and external morphological features. This set of guideline was used quite practically in describing the recent Brunei Mega MTC though in much larger scale and will be utilised to describe older MTCs as observed in the area of study. MTCs appear to be in control for the overlying sandstone deposition and it is one of the key factors in delivering sands further into the basin floor.
-
-
-
Outcrop Analogs to The Offshore Sarawak Miocene Fields, How Effective Can They Be? The Subis Limestone as an Example
Authors A.S. Dedeche, B.J. Pierson and A.W. HunterOutcrop models have typically been relied on to generate a proxy for subsurface reservoir distribution, and have been proven to provide a more complete view of both facies and reservoir quality. Despite the fact that the Tertiary carbonates of southeast Asia have been the subject of extensive exploration with proven reserves across the region, the subject of outcrop analogs have received little attention. This study focuses on the Subis Limestone Member of the Tangap Formation which forms the Gunung Subis: a huge flat-topped limestone hill that is exposed Onshore Sarawak. Satellite images of the structure were analysed confirming that it represents the original isolated carbonate platform. The platform was sampled at three main locations, depositional facies of the outcropping Subis Limestone include: lagoonal, back-reef, reef flat, reef-front, sand shoal and tidal channel. The Subis Limestone is proven to be very similar to the South China Sea carbonate buildups in terms of depositional setting and growth history. However, diagenetic history appears to be radically different. The analogy is discussed in this paper.
-
-
-
Building a Deepwater Geological Model using CSEM, Inversion and Rock Physics in NW Sabah
Authors I.N. Afifuddin, S. Kumar, R. Faisal, M.R. Rahmani and J. TomlinsonIn the wake of the recent hydrocarbon discovery in deepwater Kamunsu turbidite channel play, stratigraphic prospects are currently being pursued as part of the exploration strategy in NW Sabah, Malaysia. Stratigraphic prospects are considered high risk-high reward and require further evaluation in de-risking its petroleum system elements prior to drilling. In this paper, results from seismic inversion and structurally constrained CSEM inversion are integrated within a rock physics framework, to develop a geological model of the syn-kinematic deepwater turbidite channels that were deposited within present-day synclinal areas. This is achieved by calibrating the responses seen in the recent discovery and extrapolating the interpretation in to the synclinal structures. In this area the available 3D seismic and CSEM data with good well control presents a unique opportunity to study and analyse these rock properties and the distribution of fluid bearing reservoirs.
-
-
-
An Integrated Methodology to Address Complex Faulting In Static Models: A Case Study from Offshore Sabah
Authors S. Sharma, B. R. Oruganti, R. Henson, M. Chin, T. Basu, M. Shuhaimi, J. C. Moreno, L. Vizzini and C. A. RazakReservoir characterization of complex fault zones seen in seismic data and honoring them in static and dynamic models can be challenging. Nevertheless, understanding the fault relationships seen in seismic and other data sources, including well dip meter/image data and production data, is critical to capture the potential effect of complex structures on fluid flow within the reservoir. The problem is compounded when working in a brownfield with a stacked reservoir section of more than 2,000 ft [610 m]. There, the vertical fault relationship becomes as important as the lateral relationships, and standard pillar-grid-based methods are ineffective. A novel workflow is therefore proposed to characterize complex faults in such reservoirs using Ant Tracking, well and production data, fluid contact information, and honouring such data in static and dynamic models using new technology based on triangulated framework-based models and stair-step faulting. The paper presents a case study from the Samarang field, located offshore Sabah, Malaysia, where this methodology helped in resolving key modeling and field-development planning issues in a complex fault zone.
-
-
-
The Geology of the Tenggol Arch, offshore Peninsular Malaysia
Authors M. Tang, A.C. Yee, S. King, RA Jones, M. Farouki, K. Agbebi, Z. Ye and A. BetteridgeThe Tenggol Arch is a gentle Pre-Tertiary structural high that separates the Cenozoic Malay and Penyu Basins. The Tenggol Arch is a relatively underexplored part of offshore Peninsular Malaysia. In 2011 Lundin Malaysia became operator of a PSC covering the Tenggol Arch and acquired a regional scale dual sensor (GeoStreamer) 3D seismic survey covering approximately 2100 square km. This survey is the first dual sensor 3D seismic survey carried out in Malaysia. The 3D reveals unexpected details of both the pre-Tertiary basement geology and Tertiary sedimentology in unprecedented detail. In 2012 Lundin Malaysia used the Tenggol 3D to discover the first potentially commercial hydrocarbons in this part of the tenggol Arch.
-
-
-
Protocols for the Improved Application of Core Permeability Data in Integrated Reservoir Studies
More LessIntergranular permeability has to be quantified meaningfully if integrated studies of petroleum reservoirs are to attain maximum value. Yet, despite considerable advances in data acquisition technology for geoscience and geoengineering applications, the permeability of reservoirs that show predominantly intergranular flow is often incorrectly quantified and misused. This state of affairs has caused reservoir flow to be misrepresented with consequential distortions of projected reservoir performance. This paper redresses this unsatisfactory state of affairs by outlining technical protocols for achieving the following objectives. • Defining parametric terminology unambiguously. • Matching the permeability parameter(s) to the intended application. • Delivering permeability data that are representative of the reservoir system. • Partitioning data to achieve better defined algorithms for permeability prediction. • Honouring scale of measurement in the application of data and relational algorithms. • Reconciling static and dynamic data for field application. These six protocols are captured in a workflow for improved permeability prediction in cored reservoirs that show predominantly intergranular flow. Adoption of the resulting workflow has demonstrably improved the synthesis of static modeling data as a foundation for initialization of the reservoir simulator. In particular, the greater role of effective permeability has resulted in the better characterization of reservoir hydraulics.
-
-
-
Quantitative Mineralogical and Petrophysical Analysis of Cuttings
Authors L. Riepe and M. KnackstedtFor the characterization of most reservoir sections, cuttings are the only available “real time” and continuous option to acquire rock samples for a direct petrographic and petrophysical analysis. However the use of modern PDC drill bits only provides nearly powdered cuttings with rock fragments in the mm range, that are not suitable for any conventional petrophysical lab measurements. After the successful test and introduction of Digital Core Analysis (DCA) combined with Pore Network Modeling (PNM) technologies based on the acquisition of 3D Micro-CT tomograms at different scales for conventional core samples , we initiated a special study to test this new technology for a “Tight Gas” appraisal well to identify and quantify the mineralogical composition and topological pore structure to generate “synthetic” petrophysical properties on irregular shaped Cuttings in the mm range. A case study will be presented of a recent deep “Tight Gas” appraisal well in the Middle East, where significant sections with high gas readings and high shale and potential high TOC content could be identified from mud logs and log evaluations . Only cuttings were available to quantify and “calibrate” the mineralogical composition and potential storage and flow capacity of these different rock types . A new technology approach was applied for the quantitative mineralogical and petrophysical analysis of Cuttings with the successful application of BSEM/EDX and Digital Core Analysis (DCA) technology based on 3D Micro-CT images for a tight /shale gas “unconventional” reservoir . This new DCA/PNM technology enables a very quick characterization of reservoir rock properties even in cases where “conventional” core material and “conventional core analysis” (RCA/SCAL) are not available or possible for the reconciliation of log derived formation evaluation results.
-
-
-
Determination of Residual Gas Saturation and Relative Permeability in the Modeling of the Abadi Field
More LessUnderstanding of water encroachment mechanism from aquifer is one important factor for long-term field performance prediction, development planning, and recovery estimation. This paper presents a new systematic modeling approach for residual gas saturation (Sgr) and relative permeability.
-
-
-
Sarawak Shell’s First Repeat 4D Seismic Survey, Offshore Sarawak, Malaysia
Authors B. Gopikrishnan, R.G. Smith, B.S. Lee, J.A. Harwijanto and M.N. RabaniThe first ever repeat monitor seismic survey over a carbonate gas field in the Central Luconia province, offshore Sarawak, Malaysia has been acquired in June 2012. The time lapse (4D) seismic survey was acquired to repeat the 1992 3D as the base line and the 2008 swath. This paper discusses the challenges in the acquisition and the data processing. Preliminary results of the data processing are also presented.
-
-
-
Fracture Delineation in Volcanics,Junggar Basin
More LessThis paper presents an integrated fracture delineation approach which uses available measurements with multi-scale depth of investigation (DOI) covers “borehole surface - near wellbore - deep formation”. This paper will mainly focus on delineation of fracture effectiveness and assessment of extension and connectivity of effective fractures from borehole surface into deep formation which are key factors to control producibility of volcanic formations.
-
-
-
A Laboratory Workflow for the Geomechanical and Multi-Physics Characterisation of Shales
More LessShales are responsible for a number of significant issues in the subsurface such as overpressures and wellbore stability issues. On the positive side, shales form source rocks and seals to conventional hydrocarbon accumulations and they are also reservoirs in terms of shale gas plays. However, their long treatment as non-reservoir rocks until very recent times means we have a limited understanding of their behaviour both at laboratory and field scales. This paper describes a workflow for the thorough characterisation of shales with respect to their mechanical, physical, rock physics and petrophysical properties, detailing the impacts of such factors as stress and mineralogy on rock property response. Preservation is noted to be critical in determining rock properties, especially where the pore fluid has an impact on rock properties, for example in electrical properties, strength/elastic stiffness (static and dynamic) and permeability. Partial saturation of water is also a critical factor in gas shales and will also have a significant effect on rock properties determination and interpretation in these rock types. The impact of water content on rock properties in both fully saturated and partially saturated shales will be discussed.
-
-
-
Fluid Substitution in Laminated Sand-Shale Sequences: An Innovative Approach to Gassmann's Equation
Authors S.A. Matthews, M.A. Lovell, S.J. Davies, T. Pritchard, A. Abdelkarim and C. SirjuThis paper introduces an innovative approach to fluid substitution in laminated sand-shale reservoirs using Gassmann's equation. Erroneous results are often observed from this modelling technique; these are due to the high shale content of these reservoirs violating the assumption of a completely connected pore space with movable fluids. The innovative approach introduced in this paper aims to better constrain the results of Gassmann's equation through addressing this assumption. This is achieved through the incorporation of NMR porosity data; this identifies the movable fluid component of the reservoir porosity, which is used in the computation of "dry-frame" bulk moduli from a re-arranged form of Gassmann's equation. This innovative approach is compared to an accepted approach developed for these reservoirs, which uses effective porosity. This accepted approach violates the assumption of a connected pore space with movable fluids as effective porosity includes potentially significant amounts of immobile capillary bound water. Fluid-substitution applied using the dry frame bulk moduli estimates from both approaches indicates the advantage of the innovative approach, which derives more reasonable bulk moduli estimates when the movable fluid is substituted from in-situ brine to gas.
-
-
-
The Importance of Attribute Sensitivity in Integrated Geophysical Studies
Authors M.H. Ellis, L. Macgregor and J. TomlinsonIt is well known that often no single geophysical measurement can provide all of the information required to address a reservoir exploration, appraisal or management problem. All methods have strengths and weaknesses. Seismic data, for example provide high resolution of structure and stratigraphy, however on occasion the unambiguous interpretation of lithology or fluid properties can be challenging. Controlled source electromagnetic (CSEM) data allow resistivity to me mapped remotely, potentially providing better constraint on fluid properties, however with poor structural resolution (see Constable, 2010 for a review of CSEM technology). Well log data provide high resolution measurements of rock and fluid properties however these are only available at the well bore, and geophysical measurements must be used to interpret how these properties vary away from the well. Integration of multiple geophysical data types allows the strengths of each to be exploited, to address ambiguities inherent in the interpretation of any one taken by itself (e.g. MacGregor, 2012, Gao et al, 2012, Harris et al, 2009).
-
-
-
Sedimentology of the Major W Crocker Submarine Fan System; Analogue to the Younger Productive Fans, NW Sabah Basin
Authors A. Adli Zakaria, H.D. Johnson, C.A.L. Jackson, F. Tongkul and M. Nabil M. YusoffThe West Crocker Formation (WCF) outcrops in NW Sabah, Borneo represent a large (25000 km2), sandstone-dominated basin-floor submarine fan that was deposited in an accretionary foredeep basin complex during the Oligocene to Early Miocene period.The sedimentological analysis of the WCF outcrops has resulted in seven sedimentary facies types and five facies associations. The seven facies are categorised into three major groups: (1) sand-dominated facies (F1 to F3), comprise high- to low-density turbidites (2) debris flow-dominated facies (F4 to F6), comprises mud- and sand-dominant debris flows and mass transport deposits (MTD) and (3) mudstone dominated facies (F7) of hemipelagic settling. The five facies associations are: (1) Inner Fan Channel-Levee complex, 2) Mid-Fan Channelised Lobes,(3)Mid-Fan Non-Channelised Lobes, (4) Outer Fan Distal Lobes, (5) Mid Fan Mass Transport Complexes MTCs). A range of depositional elements are identified including channel-levee, lobes (shallow channel / channelised& non-channelised and distal lobes) and mass-transport complexes (MTCs). The four proposed laterally contiguous depositional environments for the WCF are: (1) inner fan channel-levee complex; (2) mid-fan channelised lobes; (3) mid-fan non-channelised lobes; and (4) outer fan distal lobes.The West Crocker submarine fan system is best described as a multiple-sourced, shelf-fed, Type II, low-efficiency and sand-rich system.
-
-
-
The Distribution of Miliammina Fusca in Three Different Environmental Setting of Peninsular Malaysia, Malaysia
Authors S.S. Hasan, M. Mohamed, N. Muhsin and S. JirinMiliammina fusca is agglutinated type of benthic foraminifera of which generally associated with brackish condition. In the Malay Basin the value of M. fusca occurrence becomes increasingly appreciated as it could be used as indicator of marine incursion into the basin. This observation is particularly prominent in the Lower Oligocene section (upper Group L and Group K) where the basin was not fully connected to open sea. Understanding marine incursion, its extent into the basin and associated depositional facies have important influence on the Malay Basin sedimentation, and hence directly impacts exploration efforts in the basin. Further study on the distribution of M. fusca has been carried out in modern depositional settings to determine dominant depositional facies associated with Miliammina occurrences. The study was conducted in three different modern depositional settings namely Klang Delta, Pahang Delta and Sedili Besar River of which each represents tide dominated, fluvial dominated and wave dominated depositional settings, respectively. Observations from the study suggest that the distributions of M. fusca are highly related to salinity and sedimentary facies.
-
-
-
Facies Architecture of a Complex, Heterolith-Filled Incised Valley System, Miocene Malay Basin, Malaysia
Authors M.H. Amir Hassan, R. Tahir and A.K. AliDetailed facies analysis and stratigaphic study was conducted on a productive interval in the Miocene H Group, offshore Malay Basin. Heterolithic deposits form up to 43 m thick successions which sharply overlie thick offshore mudstone. These are mainly composed of coarsening upward, heterolithic tidal bar deposits and fining upward heterolithic subtidal flat deposits. The heterolithic successions are interpreted as incised valley fills. Three valley incisions are identified in close proximity to each other. Detailed stratigraphic analysis of one of the valleys indicates the presence of a lowstand or early transgressive, prograding tide-dominated delta succession, a thin transgressive embayment succession, which is then overlain by a highstand, prograding tide-dominated delta. Succesive valleys cross-cut into each other and also migrate further eastward with time. The heterolith-filled valley incisions may represent incised distributary channels of a large delta system. Combination of initial relative sea level fall fluvial incision and progradational and transgressive tidal ravinement may have produced the deep incisions filled by tidal deposits.
-
-
-
Carbonate AvO Response in the Luconia Fields, Sarawak
By Y.F. TiongThe rationale was to model a set of seismic responses that were expected from a regional point of view, and then deduce whether fluid effects were big enough to justify for AvO inversion. For top carboante interfaces, modelling results implied that fluid effect had more impact on M when the overburden rock was soft shale. There were two top carbonate interfaces with soft overburden shale that showed big difference in M when substituted with gas. This observation supported the modelling result. For the other part of modelling, gas-water contact could possibly be differentiated from intra carbonate, but most differences were in the L domain. AvO inversion was not necessary to differentiate gas-water contact. In conclusion, there were fluid separations in the AvO modelling results, but the extra values that an AvO inversion can bring are questionable.
-
-
-
Characterization of Reservoir Rock Types in a Laminated Thin Shale-Carbonate Reservoir
Authors W. Nasifi, V. Siahaan, J. Uniir and Z. LubisIdentifying reservoir rock types in a laminated thin shale - carbonate reservoir is an essential component of reservoir characterization process. Reservoir characterization and rock typing together with post stack 3D seismic data analysis were carried out on Ngimbang laminated thin shale - carbonate formation to assess the petrophysical rock type distribution in Bukit Tua field. This predicted petrophysical rock type distribution provides valuable constraints for the development of the field. The calculated petrophysical rock types were obtained using Windland R35 equation which relates information collected from the core data. Several consistency check and quality control were applied to obtain the results which have a reliable relationship between petrophysical properties and rock types. The resulting curves at the depth interval of interest were correlated throughout the field and calibrated with 3D seismic data. Due to the thickness of the reservoir in Bukit Tua below the seismic resolution, the post stack 3D seismic data analysis is only used for structural mapping rather than inter-well petrophysical rock types distribution. Consequently, the geostatistical method is used to spatially distribute the petrophysical rock type. The results of rock type distribution clearly indicate the locations to be drilled either for appraisal or production well.
-
-
-
Pre-Carbonate Imaging: A Successful and Innovative Seismic Processing Case Study
Authors R. Alai, G. Nyein, N.N.H.C. Soh, A. Sazykin, M.S.B. Sulaiman, S.F. Zohdi, D. Suzana, M.I.B. Ismail, A. Ayub, Z.M. Dom and A.B.B. IbrahimPre-carbonate imaging is challenging due to rugosity associated with the top-carbonate surface but is essentially required to determine the deeper prospectivity in the Cycles I and II clastics. Poor images previously were undermining the prospectivity. Our integrated data processing approach managed to address these critical imaging issues and we were able to successfully see the pre-carbonate sequence and 32+ leads and prospects were identified. Our processing workflows produced final migrated images that have significantly enhanced our understanding below the carbonates and mapping of these prospects will lead us to mature these prospects into drilling locations and will hereby increase the acreage value for PETRONAS.
-
-
-
A Robust Static Modelling Approach to Support EOR Field Development Plan (FDP), Offshore Sabah, Malaysia
Authors H.P. Lee, K.F. Boey, K. Paranthaman, C.W. Hong and T.K. NyanatThis paper discusses a robust subsurface modelling approach and the quantifications of key uncertainties associated with turbidite sandstones to support water flood and EOR Field development project in an oil field offshore Sabah, Malaysia. The paper demonstrates integration of multi-disciplinary data, geological concepts and field production performance data in building static and dynamic simulation models to support Field Development Planning. Some new aspects of the field understanding are presented based on new data acquired during the two phases of development. These are: a)New geological and petrophysical interpretations based on new wells calibraeted to reprocessed seismic data. b)Building of multi-scenarios deterministic models (Low, Base and High case)
-
-
-
Fractures Identification While Drilling
Authors M. Bazara, A. Basyouni, M. Al-Sharafi, Z. Al-Kindi and Z. GhafriDrilling a highly deviated wells in a heavily fractured and complex heterogeneous Carbonate formations is a challenging process that requires a real time monitoring and utilizing an MWD and LWD technology. -Currently PDO is developing X field and drilling horizontal wells for Gas in A formation in which the reservoir compromises a heterogeneous vuggy limestone and a fractures network that is distributed all over the field. The challenge faced during drilling is the total drilling mud losses due to presence of major fractures consequently those fractures represent a threat for early water break through and shortening the life of the well. PDO has utilized the Ultra high resolution LWD resistivity images in several wells to tackle this problem, which successfully helped to identify the fractures zones that contributed to the drilling mud losses and design completion to isolate those fractures zones. As well as selecting a proper perforation zones away from the fractures. The Geological interpretation of the high resolution resistivity images revealed the presence of a few major conductive fractures that were possibly enhanced by drilling and a large number of partial discontinuous conductive and resistive fractures.
-
-
-
Have We Done Enough Research in Gas Flood IOR/EOR Technology
By A. HageFurther experimental work and research is mandatory for successful IOR/EOR piloting. Further investigation is required to ensure full understanding of phase behavior at different conditions and ensuring flow assurance under secondary and tertiary depletions. The techniques used to determine MMP and MME are not optimum. Depressurizing experiments showed contradictory results against titration experiments for AOP/AOC against CO2 and N2. Core-flood experiments and proper up-scaling procedures are also questionable, taking into consideration flow-assurance challenges of solid precipitation and deposition causing potential formation damage, which necessitates further investigation for each phase of the workflow process
-
-
-
Using Integrated Modelling Approach to Evaluate the Use of IWAG EOR Process
Authors S. Vijapurapu, A. Ghosh, S.F. Kho, K.H. Leong, G.J. Reijnders and G. StoneField A situated, offshore Borneo, Malaysia, with 30 years of production, was identified as candidate for Enhanced Oil Recovery (EOR). Immiscible water alternating gas (iWAG) was identified as a suitable EOR process from screening studies. Implementation of Enhanced Oil Recovery schemes for brown field re-development requires an understanding of recovery mechanisms from pore-scale to the field scale, and commonly requires the use of reservoir models which can represent the reservoir at these different scales. A fit-for-purpose integrated reservoir modeling (IRM) approach to analyse the risks and benefits of IWAG process will be presented in this paper. Results of the study would help in understanding the IWAG process and in the implementation of the EOR scheme in the other fields in the region, which have similar geological setup and depositional environments.
-
-
-
Thin-Bed Geology and Borehole Image Logs - Back To Nature
More LessIf we work with the models for too long, we risk forgetting what nature really looks like and our preferred models and methods may take over with a considerably less-than-optimal effect. Occasionally, we need to re-calibrate our perceptions with a dose of reality. In reality, thin beds are found in almost all sedimentary environments and are the results of processes that involve pulsed sedimentation from varied flow regimes. Thin beds may represent instantaneous events (minutes) or deposit over hundreds of years. Thin beds are characterised by a range of structures, textures, and composition that includes not only thickness but bed-boundary sharpness, grain size changes, sorting, bioturbation, mineralogical variations (detrital and cementation). All these factors contribute to the complexity that our models necessarily attempt to simplify. A better understanding of the depositional and post-depositional processes that result in thin beds gives us a deeper appreciation of why thin beds are difficult to evaluate. A deeper appreciation should result in better estimates of P10, P50, P90 values and translate into improved uncertainty limits. In the absence of core, only borehole image logs provide us the data from which we can conceptualise and interpret depositional processes and allow us to reduce uncertainty.
-
-
-
Predicting Net Sand at Kebabangan Field for 2013 Drilling Campaign, DW Sabah, Malaysia
Authors A. Bolhassan and C. M. CurtisEstimation of net-to-gross in a complex amalgamation of varying reservoir bed thickness presents many challenges. Deploying conventional shale volume cut-offs to determine net sand distributions in these types of reservoirs, as seen in the Kebabangan Field, can be misleading because conventional logs can by-pass potential hydrocarbon bearing intervals due to the so-called “low resistivity and low contrast” response that can occur in thinly laminated beds. Using the thin bed analysis (TBA) with Thomas-Stieber approach to quantify net sand within both thick beds and thinly laminated beds was found to be an effective and repeatable method in evaluating net sand distributions in a well; mainly because it utilizes only basic log data as inputs; and therefore, can be applied in all the planned Phase I development wells and reservoir intervals. By integrating and comparing the net sand results with the sand count from core and log images, we can demonstrate the successful applications of Thomas-Stieber approach in quantifying net sand in both thick blocky sands, as well as, thinly laminated reservoirs sands in Kebabangan field.
-
-
-
Application of Matching Pursuit to Spectral Decomposition, Issues and Solutions
Authors D.C. Adams and D. MarkusApplications of Matching Pursuit signal analysis methods have made significant inroads into use in seismic data analysis. In our review of the geophysical literature we found applications to migration, interpolation, spectral decomposition and others. Our review also indicated three areas where thorough understanding of practice, as it applies to spectral decomposition, is lacking and leads one to ask the following questions: (1) given that Morlet wavelets are commonly used in the analysis, do dictionaries based on them adequately predict synthetic and extracted seismic wavelets? (2) Can the properties of a seismic trace be used to limit the dictionary to a reasonable size? (3) How well do instantaneous phase and frequency attributes predict the Matching Pursuit solutions? This paper seeks to answer these questions.
-
-
-
Novel Method to Improve Seismic Resolution Through STFTHC Algorithm
Authors M. Sajid, D.P. Ghosh and Z. ZahirNovel algorithm Short-Time-Fourier Transform-Half-Cepstrum(STFTHC) is proposed in this paper to increase resolution of thin beds though broadening the frequency bandwidth of seismic. The new proposed algorithm increase the resolution without adding any high frequency noise as observed in different industry available algorithm of seismic resolution. Testing on wavelet, 1D thin layer model, 2D thin layer model and on real seismic proves is effectiveness for seismic resolution and shows high correlation coefficient with well reflectivity as compared with original seismic.
-
-
-
Advances in Sedimentary Facies and Depositional Environment Analysis of the Subsurface Late Miocene Offshore Borneo Using Oil-Based High Resolution
Authors M.N.A. Bakar, M. Ismail and N.S. KhalidIn this paper, borehole image are used for a sedimentological study. More than 3600ft of image log data is subdivided into image facies related to depositional processes from which the sub-environments of a shallow marine sequence is inferred. The borehole image provides excellent examples of sedimentary features such as cross bedding, flaser bedding, lenticular bedding, bioturbation, soft-sediment deformation, and de-watering structures; capturing the high heterogeneity of the formation. These features enable us to interpret sedimentary facies in detail and classify them in terms of their depositional processes. Vertical siccession of these sedimentary facies are then associated to infer their depositional environment such as shelf, shorefaces, and beach-foreshore environments.
-
-
-
Image Based Petro Physics for Thin Bed Analysis Using the Bore Hole Image Data
Authors P. Kalathingal, R. Holland and R. MartinezThe Bore-hole Image tool provides the vertical resolution required for the thin bed analysis. Image Petrophysics is one of the applications could provide the high resolution Petrophysical properties like porosity, permeability and also will provide the vertical anisotropy, grain size distribution and volumetric that aids in the better understanding of thin bed formation evaluation
-
-
-
Core–log Integration for a Fractured Reservoir
By H. DürrastIn hydrocarbon exploration fractures play an important role as possible pathways for the hydro-carbon flow and by this enhancing the overall formation’s permeability. Advanced logging methods for fracture analysis, like the borehole acoustic televiewer and Formation Microscanner (FMS) are available. However, open and with water or hydrocarbon filled fractures are also sen-sitive to electrical and other conventional logging methods. The integration of core and log data from a sandstone reservoir show that fractures can be identified with conventional logging; however limitations still exist.
-
-
-
Subsurface Facies Analysis and Reservoir Characterization of the Late Oligocene Penyu Formation, Shallow Marginal Marine to Low Energy Deltaics Sediments, Penyu Basin, South China Sea, Malaysia
Authors M. Johansson, S. Farag, R. Lafferty, R. Rahman and W. TanThe subsurface facies analysis was based on a single well penetrating the Late Oligocene K1 – K10 sands of the Penyu Formation in the Eastern reaches of the Penyu Basin. This well acquired an extensive data suite including; conventional wireline (gamma-ray, lateralog resistivity, density-neutron, acoustic), specialized data such as electrical imaging, nuclear magnetic resonance, elemental capture spectroscopy and dielectric propogation. In addition, the entire reservoir succession was conventionally cored and drill-stem tested. The borehole conditions were good and therefore the data quality was excellent for detailed facies analysis. The image log was calibrated to core, and detailed facies analysis was extended beyond the core using the geological features from the images, the porosity and permeability from conventional density-neutron and the nuclear magnetic tool and the mineralogy from the elemental capture spectroscopy.Three major lithological groups were identified sandstone, heterolithic and mudstone with each facies often transitional to the next. The overall depositional environment has been interpreted as restricted shallow marginal marine bay adjacent or proximal to a low energy delta or estuarine mouth.
-
-
-
Statistical Analysis of Faults Attributes. Taking Into Account the Truncating and Censoring Effects
Authors D. Kolyukhin and A. TorabiA statistical analysis of single faults' attributes was performed. A truncated power-law was compared to a simple power-law approximation. We have studied the relationships between fault displacement and fault length, damage zone width and fault core width. The algorithm of statistical analysis of fractures length distribution under the resolution effect is developed.
-
-
-
Turning Hazards Into Resources, Success Story from DS-1
More LessOver the last three decades, the Malaysian exploration industry has matured significantly. Despite its maturity, new plays continued to be evolved and enable PETRONAS to play its role in support of the government policies which aim to reduce dependency on oil as the main energy source. Recent discovery of a shallow gas accumulation in what was once considered a shallow drilling hazard to be avoided, has now become a new play promising substantial commercial gas resources. DS-1 has proven to be the largest shallow gas fields tested to-date, producing gas at a depth as shallow as 512m MDDF. In addition several untested reservoirs, some of which yielded gas on MDTs were encountered. The shallowest interpreted gas reservoir occurred at a depth of 404 m MDDF. The discovery at DS-1 has given impetus and forced a relook at a forgotten play in Malaysia gas exploration history. The success had changed the overall exploration strategy in PETRONAS and subsequently enhances PETRONAS resources in meeting the demand of gas in Peninsular Malaysia.
-
-
-
Imaging Below Shallow Gas with Full Azimuth Acquisition: A Solution Design and Modeling Case Study in Offshore Malaysia
Authors M.C.K. Choo, M. Branston, M. Tham, P. Baltensperger and M. WysockiThe image of the target in this case study is affected by zones of shallow gas/high Earth attenuation in the overburden. The goal of the study is to determine whether the imaging of the seismic below these areas can be improved through the application of advanced acquisition designs, eg. increased azimuth, long offset acquisition. Following the successful completion of a proof of concept test using a realistic synthetic model, illumination analyses were carried out over the survey area to determine the illumination characteristics of the legacy survey and the circular shooting acquisition to help understand the impact of the shallow gas bodies on the amplitude across the target horizons. The non-conventional circular acquisition approach has the potential to improve upon the azimuthal sampling achievable with the traditional straight line narrow azimuth survey. To determine the relative benefits of the full azimuth approach against the narrow azimuth legacy data for this specific area, additional target orientated analysis was conducted. This consisted of establishing the full range of reflector dips and azimuths (outside of those in the existing structural model) which could be imaged by each technique combined with simulating local PSDM images for the key areas of interest.
-
-
-
Broadband Acquisition - Imaging Below the Shallow Gas
More LessIn this deep water marine seismic dataset, it has been observed that imaging and resolution of the deep section is poor. The amplitudes of the events at depth are deemed to be affected by the shallow gas clusters. A 3D illumination study was carried out to determine the illumination characteristics of the proposed multi-azimuth acquisition geometry. Of main interest is the comparison between the amplitude maps corresponding to the conventional towed marine and broadband type seismic acquisition. The key method presented in this paper is that we have incorporated earth attenuation into the 3D model and amplitude output.
-
-
-
Impact of Gas-Sands and Gas-Clouds on Wave Propagation through Numerical Modeling
Authors R. Alai, A.S.B. Saleh and M.F. AkalinIn the Malay basin often shallow gas leakage and presence of partially gas saturated sands are major issues in seismic imaging and often the presence of gas results in poor quality, low S/N-signal-to-noise ratio “washed-out” vertical bands in seismic sections causing challenges in seismic data processing and interpretation. Although gas cloud imaging may be improved through shear waves, in the following examples acoustic models have been used to illustrate the impact of internal multiples in contributing to the complexity of imaging and illumination issues in Malaysian gas-sands & gas-cloud present environments. The examples illustrated in this abstract clearly show the impact of gas-sand and gas-cloud presence on wave-propagation in a simple geological setting.
-
-
-
Integrated Reservoir Characterization and Static Geomodeling of Senoro Field, Senoro-Toili Block, Sulawesi, Indonesia
Authors K.W.A. Kwartono, D. Hasanusi and R. WijayaSenoro field is a proven carbonate gas reservoir, located in the north-eastern region of Senoro-Toili Block, Sulawesi. Six wells have been tested 18-20 MMSCFD of gas rate from Miocene carbonate of Minahaki platform. A multidiscipline study was conducted by integrating geology, geophysics, petrophysics and reservoir engineer data. This paper presents reservoir characterization and static geomodeling study to identify new well proposals for further future development plan. This study was commenced with structural model configuration based on 2D seismic interpretation and well log correlation. Facies was analyzed based on core and log calibration, while at un-cored intervals, it was predicted using electrofacies approach. Porosity-permeability cross plot was formulated by incorporating facies definition. Accordingly, 3 transforms were recognized. To distribute facies and porosity, sequential geostatistic approach was applied by incorporating AI model as secondary trend, while permeability model was calculated based on aforementioned transforms. J function method was performed to estimate water saturation in the transition zone, so that capillary-gravity equilibrium was taken into account. Finally, volumetric calculation was quantified based on 3D porosity and water saturation, while permeability model was used in dynamic flow simulation. Based on the reservoir simulation, 15 new wells have been proposed for field development optimization.
-
-
-
Petroleum Systems Modelling: A Case Study from Dutch Central Graben (Offshore Netherlands)
More LessExploration has seen a considerable improvement in recent years when it comes to understanding basin and reservoir geology. From regional scale to the reservoir level, integration of various geoscientific disciplines during exploration increases the understanding of critical parameters reducing risk significantly. By integrating geological, geophysical, petrophysical, and reservoir data one can model the evolution of basin and petroleum systems with time. To improve the understanding of petroleum system elements, 3D petroleum systems modeling of the Dutch Central Graben was performed. This helped in understanding of how a reservoir has been charged with hydrocarbons; including the source and timing of hydrocarbon generation, migration routes, quantities, and hydrocarbon type in the subsurface. Hydrocarbon accumulations were observed in the Lower Graben Sandstones and the Greensand Reservoir units, within different structural traps. Predicted modeling results agree with some of the discovered fields in F3 block, of which the F3-FB field proved to be economically viable and has been producing commercial quantities of hydrocarbons since last 3 decades.
-
-
-
Sequence Stratigraphic Approach to Identify Upside Potential in Matured Block Sk307, West Baram Delta, Sarawak
Authors D.H. Sapri, W.C.H. Wong, A. Chuang and O.A. MahmudThe sequence stratigraphic study of matured Block SK307 in the West Baram Delta is documented and its sequence refined. Integrating various data, the study has established a new stratigraphic framework in the area. Up to eight sequences has been recognized that cover the Miocene through to the Present. A conceptualized petroleum system model is presented and the upside potential traps in this area are also highlighted and discussed for further exploration.
-
-
-
Mass Transport Complex (MTC) on NW Borneo Slope; Influence of Thrust Related Folding on Its Stratigraphic Development
Authors A. Adli Zakaria, H.D. Johnson, C.A.L. Jackson and M. Nabil. M. YusoffThe Lingan fan system in a toe-thrust foldbelt area is a unique example of mass transport complexes (MTCs) in a channelised fan located on the steep, tectonically active NW Borneo margin, connected to a series of main slope feeder channel complexes.These thrust-related growth folds and their syn-depositional topographic features represent a major control on sedimentary pathways and stratigraphic development of these gravity flow deposits in the slope and basin floor areas.Seismic stratigraphic and facies analysis combined with attribute interpretations of the three-dimensional seismic data volume are used to study the temporal and spatial distribution and stratigraphic development of mass transport complexes (MTCs) in slope and basin floor deposits of the Lingan fan system.The analysis shows how the temporal and spatial distribution of the deepwater facies and stratigraphic development of such syn-depositionally deposits are influenced by the prominent syn-kinematically thrust-related growth folding structures in the study area. The study provides a better understanding of temporal and spatial distribution and stratigraphic development of MTCs in the slope and basin floor of the mixed sand-mud Lingan fan system. Also, the results reveal how significant is the influence of syn-kinematically thrust-related growth folding to the stratigraphic development of the deposits.
-
-
-
The Scratch Test: a High Resolution Log of Rock Strength with Applications to Geomechanics and Petrophysics
Authors T. Richard, C. Germay, S. Woo Hsuan Thai and E. MappanyompaIn this paper, we present the principle of the scratch test, a novel state of the art laboratory test carried out on core samples. The test provides a unique high precision continuous profile of the rock strength along the core sample. The standalone portable and semi-automated testing equipment, dubbed "the Wombat", allows testing up to 3 meters of core sample per hour. This simple and robust test requires minimal sample preparation (carried out with the machine), is applicable over a wide range of sedimentary rock with strength ranging from 0.5 to 200 MPa, and is only partially destructive with the extent of damage limited to a groove of 10 mm wide and few millimetres depth along the core sample. The results are not affected by the sample size, and yield a continuous profile of the uni-axial compressive strength of the rock with a precision of less than 1 MPa. Besides direct applications to geo-mechanics, this high resolution log provides a unique measure of the scales, dispersion and distribution of heterogeneities along the core sample offering new perspectives in petro-physics with application such as strategy for core plugs selection, correlations with measurements on plugs but also well logs.
-
-
-
Borehole Acoustics Characterization in Deepwater
Authors J.A. Donald, M. Sanders and L. AnisThe subsurface stress state in deepwater wells is critical for drilling and completion operations due to the reduced litho-static column in the overburden. The vertical stress in this case may not be the major principal stress as would be conventionally assumed in shallow water environment due to a difference in the weight of the overburden. As a result, mud weight windows are narrower and production induced stress changes are more substantial, requiring better predictability of the initial stress state. New techniques have been developed to estimate the maximum and minimum horizontal stress magnitudes using a combination of pore pressure, overburden stress and advanced full-waveform sonic data derived from the shear radial profiles and 3 shear moduli. Knowledge of the wellbore stress state (axial, radial and tangential stresses) along with a non-linear elastic model is used to estimate the principle stress magnitudes. Since deepwater sediments are extremely sensitive for acoustics methods to detect changes in stress, this method is suited to model this lithology. A case study will be presented from a deepwater well in Malaysia where all three principal stresses are determined through evaluation of advanced 3D acoustic characterization of the wellbore.
-
-
-
Optimization of the “Fractured Triangle” to Determine Matrix/Fracture Permeability Ratio, Partitioning Coefficient and Intensity Index in Terms of Storativity Ratio from Pressure Transient Analysis
By T. ElkewidyThe graphical technique along with newly derived formulas yield the most important petrophysical and engineering parameters about the heterogeneous naturally fractured reservoir including effective fractures, matrix and skin systems volumes, partitioning coefficient, fracture intensity index, formation resistivity factor, formation tortuosity, effective drainage radius, damage radius, effective cementation exponent, fracture porosity, matrix porosity, storativity ratio, in addition to fracture permeability, matrix permeability, damaged permeability, average permeability, pressure drop across the damage area, skin factor, damage permeability, average/dimensionless diffusivity factor, flow efficiency, damage ratio/factor, economic implication of formation damage, average hydraulic “flow” unit quality index. The technique is extended to derive the fracture partitioning coefficient and intensity index in terms of storativity ratio all derived from the fractured triangle of pressure transient analyses along with the matrix/fracture permeability ratio. Again the graphical technique of the fractured triangle has proven to be successful for all kinds of fractured reservoirs including clastics, carbonates and basement rocks. This paper will present the theory along with successful field applications with the results.
-
-
-
An Investigation of Overpressure Mechanisms: A Case Study of Offshore Turkmenistan
Authors I.H.S. Idris, A.O. Osundina and F.M. WijnandsAbstract The main overpressure mechanisms identified in the South Caspian Basin are tectonic stress (rapid subsiding and sedimentation) and temperature (hydrocarbon generation). This paper will focus on the Block ABC located in the South Caspian Basin, Turkmenistan. The overpressure magnitude at the eastern part of the block is as high as close to 12000 psi whereas the western part of the block shows the magnitude of approximately 7000 psi at the same depth (3500m TVDss). In general, the formation pressure of this block shows an increasing in pressure from approximately in the RS-2 down to formation RS-8a. The formation pressure regressed down to RS-8b across the study area. This paper will try to investigate the main mechanism(s) that create different magnitude of overpressure in the eastern and western part of Block ABC. Once the overpressure mechanisms are identified, this paper will try to present an approach in predicting the pore pressure in this area.
-
-
-
Breakthrough into Deep HPHT Play in West Baram Delta - Success of Real-time Pore Pressure Monitoring
Authors C.A. Ibrahim, M. Ariff, M.H. Wahab, F. Wijnands and J. IsmailExploration for deep overpressure plays has become very important in West Baram Delta as this region has been extensively explored for more than 100 years. First ever HPHT drilling campaign was commence in December 2011 and these two recent HPHT wells drilled have successfully tested the deep seating overpressure playtype at depths more than 4500m below mudline. Both wells were drilled close to its 15,000 psi BOP operational limit.Well-B from this HPHT campaign has recorded the highest reservoir pressure to date in Malaysia, approximately 14000psi with temperature of 152°C. Integrated pre-drill pore pressure model has allow both wells to be drilled pass through the high overpressure section safely. Inflationary overpressure predicted to be the major threat in this campaign where well could bump into steep pressure jump with just few meter interval. Real-time monitoring on the various gas trend (Swabbed Gas, Background Gas, Connection Gas, Trip Gas, Pump-off Gas) found to be the key success indicator for this HPHT campaign. This event gas trends and its magnitude were the primary indicators used to estimated the pore pressure. The slightest presence of an event gas peaks will have to be flagged and MW’s was raised accordingly. The threat of inflationary overpressure in this campaign has also been succesfully overcome by this new approach of real-time pore pressure monitoring.
-
-
-
On-Flank Stratigraphic Potential of Cycle II
Authors NSalmi Abdullah, A. Rauf and H. MohamedThe Balingian Province is one of the most prolific petroleum system in Sarawak that has been actively explored since the early 1920's. This province is bounded by West Balingian Line to the west, Central Luconia to the north and Anau-Nyalau fault & Tatau horst-block to the south. The producing intervals in the area is at Cycle I & Cycle II at Western Balingian and Cycle II & Cycle III at Eastern Balingian. To date, more than hundreds of exploration & appraisal wells were drilled in the area. The purpose for this study is to review the remaining potential of Cycle II reservoirs in the western Balingian which has yet to be explored or developed especially on the flank of current fields where the Cycle II has been discovered on the crest of the structure. The study is focused on the area surrounding the Bayan field toward eastern area including the Merapuh structural trend (Serendah-Belum-Merapuh fields). The crest of the structures where the majority of hydrocarbon may have been discovered today are probably not the optimal locations for the best Cycle II stratigraphic targets. This poster propose on-flank stratigraphic exploration potential nearby major structural trends.
-
-
-
North Baram & North East Luconia Play Analysis
Authors NSalmi Abdullah and M. HarminzarThe North Baram & North East Luconia play analysis project objective is to further evaluate the remaining potentials in the open block which is straddling the West Baram and North Luconia Provinces. The study area covers a total of 25000sqkm extending from NW to SE of the Sarawak Basin which fall across two of the most prolific geological provinces in Malaysia, the Baram and Luconia provinces. This area underlain by three different geological provinces, the eastern part of the North and Central Luconia provinces and the extension of West Baram Delta province. There are three major play types were recognized and actively explored in the area namely; Pre-MMU (Cycle I & II) play at the North East Luconia, Post-MMU play (Upper Cycle V-VI) at North Baram Delta and Carbonate play at the Central Luconia province. However there are still remaining potential of Lower Cycle V play in N Baram Delta, Pre-carbonate play in Central Luconia & Post-MMU play in NE Luconia that have yet to be tested and evaluated.
-
-
-
An Integrated 3D Seismic Interpretation and Regional Tectonic Study Strengthens Evidences of Wrench Faulting and Understanding of Hydrocarbon Trapping Style in NW Balingian Province
Authors Nor Zarith Sofia BT M Zainal, Y.H. Teng, M Farid M Pushiri, A. Nurhono and S.T. GohThrough seismic interpretation, the team observed a complicated structural feature in West Balingian Province which is probably a product of wrench-fault assemblage tectonic. Cycle I and older rocks were folded as a result of compressional force during the Late Eocene’s collision of Luconia block and Borneo Basement. During Oligocene, Sarawak margin subsided rapidly due to overburden Cycle I sediment infill from the uplifted of Rajang group. The uplifting happened again during Late Oligocene, top of Cycle I was eroded, forming unconformity at base Cycle II. From Cycle II upwards sequences, series of normal faults associated with graben structure were observed in the seismic data. These faults are probably result of extension component derived from wrench movement during Early Miocene to Pleistocene when South China Sea opened. The opening alongside with anticlockwise rotation of Luconia Block (Borneo) induced strike-slip movement at the study area which results in the wrench faulting (Hazebroek and Tan, 1993; Hazebroek et al., 1994). Major unconformities were also observed in seismic data at base of Cycle III resulted from uplifting of NW Balingian sub-province. All structures are interpreted using 3D seismic data, analyzed its age of deformation with the framework of regional tectonic history.
-
-
-
Origin of the Canada Hill - A Result of Clay Hydraulics at the Pleistocene/Holocene Border?
Authors F.L. Kessler Sdn Bhd and J. JongThe young (reactivated) Canada Hill tectonics can be explained by hydraulic pressure onto a semi-liquid pillow of Setap Formation clay. Inferred Quarternary horizontal pressure in NW-SE direction, in combination with strike-slip tectonics, plus some overthrusting, triggered a diapiric remobilization of the mobile clay pillow beneath the Canada Hill. The diapiric flow was refocused upwards, in direction of the lowest pressure. As a result, the sequence above the Setup Formation clay, parts of the Miri Formation, were uplifted and emerged beyond the Pleistocene peneplain. Assuming a hydraulic uplift in the order of 400 ft and a lithostatic pressure gradient of 0.9 psi/ft, additional lateral pressure above the 360 psi equilibrium pressure would have prompted the clay core to move. Semi-liquid clay pillows maybe in the cores of many NW Borneo structures, and one should investigate this concept further in the context of structural growth features.
-
-
-
Could Unconventional Developments in Asia benefit from the North American Experience?
Authors P. Kalathingal and C.A. PoonThe geology and geography of unconventional resources vary as every unconventional play is different. Geopolitical and economic factors have important role in the developing unconventional plays. Asia needs more gas and developing unconventional gas is an attractive alternative for energy security and economic growth. Technology expertise transfer from the IOC and service companies to East Asia, could definitely help the region exploit unconventional resources without having to re-invent the wheel – already implemented in North America
-
-
-
Estimating Source of the Gas in One of Gas Hydrate Accumulations of the Iranian Deep Waters
Authors E. Afazeli, S. Gerami and N. Keshavarz Faraj khahRecent seismic surveys detected thick layer of free gas underlying hydrate bearing sediments through observation of direct seismic attributes in one of the Iranian deep waters. Furthermore, favorable geological condition is evidence of gas hydrate occurrence in the area of study. The gas hydrate stability zone (GHSZ) could be estimated either by bottom simulating reflector (BSR) horizon directly or by thermodynamic calculation of stability in sediments. However, thermodynamic calculations are subject to very large uncertainties and there is almost no model to quantify the impact of effective variables in stability calculations. In this paper we present a quantitative model of affecting variables on the thickness of the GHSZ within the study area, based on a conceptual model of the thickness of the GHSZ varying over a wide range of input variables and use it along with geophysical model of the thickness of the GHSZ for evaluation of the source of the gas in gas hydrate accumulations of the area. The results of this study indicated thermogenic gas components which reveal the existence of a conventional gas reservoir in deep depths of the study area.
-
-
-
Unconventional Resources Uncertainties: Everywhere Is Not The Same!
Authors S.Z.M. Mohammad, A.S.K.Z. Zakaria and M.M.M.A. Mohamed AriffinPetronas foray into unconventional resources started with the Gladstone CBM project in Australia in 2006. Since then various unconventional assets comprising of oil sands, shale gas and coal bed methane have been evaluated for technical and commercial potential. Despite similar methodologies used when assessing unconventional resources, they possess a high range of variability and uncertainty in its reservoir properties. This is debunking popular myth that “everywhere is the same”. Also controversial is the way productivity and resource is defined, which needs to be understood thoroughly to determine the value of the asset and fulfill pertinent investment criteria. Case studies of unconventional resources evaluation in are shared to illustrate the issues outlined. The uncertainty in unconventional play ranges from as early stage of resource estimation to the productivity of the reservoir. As seen from our case studies, these uncertainties are the interplay of regional geology, methodology adapted and operational practice.
-
-
-
Accurate In-Situ Fluid Analysis Aids in Reliable Reservoir Evaluation in Pearl River Mouth Basin
By C. XianThis paper will present two case studies accurate in-situ fluid analysis aids in reliable reservoir evaluation in Pearl River Mouth basin. In the first case, no reliable pressure gradient was achieved to indicate formation fluids due to severe supercharging despite an extensive pressure survey. Five in-situ fluid analysis stations including three sampling stations were conducted. Comparison of the in-situ fluid analysis data, including C1, C2, C3–C5, C6+, CO2, gas/oil ratio (GOR), and density, indicates excellent tool resolution. The vertical variation of oil properties reveals a more complex system than the initially expected single oil column. Two tendencies of oil property variations may be controlled by two depositional systems. Vertical compartmentalization was then characterized. A second case involves a gas reservoir containing significant CO2 with a thin carbonate layer between the upper and lower sections. Accurate in-situ density measurements combined with pressure transient analysis enabled reconstructing the fluid gradients and gas/water contact. In-situ fluid measurements indicate that the thin carbonate could act as a vertical barrier. These case studies demonstrate that the use of reservoir fluid properties can be extended from standalone PVT results to delineation of important geological features such as compartmentalization and petroleum systems.
-
-
-
Using NMR and Pressure & Sampling Technologies to Meet Reservoir Characterization Challenges of Shallow Gas Bearing Sandstones A Case Study - Peninsular Malaysia, PMO
Authors E.A.A. Najm, A.B.M. Hassan, D.H. Xuan, M.M. Altunbay, K. Sinha and I. DarUsing NMR & PT&S in HC typing reservoir at near critical condition
-
-
-
Extending the Use of WFT in Tight or Fractured Reservoirs with a New-Generation Dual Packer and DFA Module
Authors C. Mas, S. Sugiri, M. Mirayanti and O. SuriyantoA case study in using the WFT with New Dual Packer and Advanced DFA in 5 exploration wells in Indonesia. The case study include the tight sandstone, tight carbonate, and fractured reservoir in WBM environment.
-
-
-
Geosteering with Azimuthal Resistivity Tool in Thin Oil Rim Horizontal Well - A Case Study from the Malay Basin
Authors N.A. Che Sidik, C. Sathasivam and T.J. FochtThe application of Azimuthal Resistivity tool has been used in 2 fields operated by Newfield Peninsula Malaysia in the Malay basin. To-date a total of 27 horizontal wells have been drilled with azimuthal resistivity tool. The expectation is that the tool provides key information on fluid and/or structural boundaries that helps to improve the trajectory of the horizontal section of the wells. The key drivers are to stay at certain elevation above oil-water contact while maximising net pay. The tool is capable to look deeper into the rock formation giving estimation of distance to fluid or lithological boundaries. This paper explains the successfully application of azimuthal resistivity tool and how this geosteering technology has benefited Newfield in meeting its reservoir targets
-
-
-
Controlled Wellbore Implosions; A New Frontier in Production Enhancement” A Novel Low Cost, Low Risk Technique That Shows Consistent Results
Authors A. Adil Busaidy, Z. Zaouali, C. Baumann and E. VeglianteNear wellbore damage is often blamed for many production problems, it can manifest itself in many ways and is caused by almost anything that disturbs the formation; even producing hydrocarbons can lead to near wellbore damage. A new technique of consisting of producing controlled implosions constitutes the most effective way of removing perforation and other types of near wellbore damage, and this technique lends itself to provide quantitative values of well damage removal. This paper discusses how this new technique was developed, from concept and modeling to its effectiveness in the field as demonstrated by a number of jobs on wells with different types of damage. The results are extremely encouraging; in some wells production has increased by as much as three to four times, this production increase is sustained and the rate at which well formation damage occurs is significantly lower.
-
-
-
The Use of Seismic While Drilling in Ultra Deepwater Drilling - A Case history from Andaman Sea
Authors T.K. Lim, R.K. Rana, M.L. Khaitan, F. Dotiwala and S.C. ShekarThe advancement in logging while drilling (LWD) technologies and computing power has revolutionized the utilization of seismic data in the exploration life cycle. Not only is surface seismic being used for the study of regional geology, petroleum system, prospect identification and volumetrics through integration with well data, it is now being successfully used to ‘guide’ deepwater drilling and manage drilling uncertainties, particularly drilling target depths. This new initiative led to seismic while drilling (SWD) technology being used for first time by Oil and Natural Gas Corporation, ONGC, on their Andaman Seas deepwater drilling campaign. We present a method that makes use of LWD technology with little impact on drilling operations. The SWD checkshot was acquired at every drill string stand depth without disturbing the normal drilling operation and rig time. As drilling continues, the updated velocity model was used to:- • Confirm the drill bit position on the revised surface seismic section as drilling continues • Recalibrated Pore Pressure prediction The case study demonstrated that SWD technique was successfully used during the deepwater exploratory drilling campaign in Andaman Sea by ONGC that help saving of more than 10 drilling days.
-
-
-
Organic Matter Characteristics of Late Cretaceous Sediments: Implications for HC Exploration in Chad Basin, NE Nigeria
Authors A. K. Adegoke and W.H. AbdullahOrganic geochemical analyses and organic petrography of selected samples from various stratigraphic units penetrated by five exploratory wells (Kemar-1, Kinarsar-1, Kanadi-1, Ziye and Tuma-1) in Chad (Borno) Basin indicate that they are generally lean organically, and they are dominated by Type III and Type IV kerogen. Though, fair to good potential for gas generation exist in some parts of the basins, especially where the samples show high TOC, extractable organic matter (EOM) and hydrocarbon yield. The organic matter was deposited in marine environment, with substantial terrestrial input in anoxic-oxic depositional condition. This probably accounted for the poor preservation of the organic matter and the variable environment of deposition. Various maturity data (Vitrinite reflectance, Rock-Eval Tmax, Production Index, Bitumen/TOC ratio and biomarker distributions) suggested that the sediments, especially the lower part of the Fika Formation and the Gongila Formation, which composed majorly of shales and carbonates, have reached the early to peak stages of hydrocarbon generation.
-