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Petroleum Geoscience Conference & Exhibition 2013
- Conference date: 18 Mar 2013 - 19 Mar 2013
- Location: Kuala Lumpur, Malaysia
- Published: 18 March 2013
1 - 50 of 103 results
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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?
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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