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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
41 - 60 of 103 results
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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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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.
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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.
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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