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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
21 - 40 of 103 results
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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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