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EAGE Conference on Reservoir Geoscience
- Conference date: December 3-5, 2018
- Location: Kuala Lumpur, Malaysia
- Published: 03 December 2018
1 - 50 of 87 results
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Paleogeographic Reconstruction Based On Tectonostratigraphic And Halokinesis Evaluation, Nw Kuwait
Authors A. Amer, A. Sajer, T. Al-Adwani, H. Al-hebail, H.H. Al-Shammari, A. Abdullah, B. Chakrabarti and S. MajumdarSummaryThe objective of this work is to reconstruct the paleogeographic distribution of the depositional facies of the Late Triassic to Late Jurassic, namely Minjur, Marrat, Dharuma, Sargelu and Najmah formations over the Mutriba structure, North West Kuwait. This paper suggests that during the Late Triassic, Mutriba structure was dominated by extensional tectonics that resulted in a NW-SE trending graben and horst system. This was followed by halokinesis as a result of changes in sedimentary load and basement activation during the Early-Lower Jurassic. During the Late-Lower Jurassic strike-slip kinematics dominated the area and during the Early-Upper Jurassic the strike-slip tectonics was aborted as a result of halokinesis and tectonic reactivation. The Late Jurassic was dominated by transpressional tectonics and the inversion of some faulted.
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Fault Seal In Sabah Deep Water Fields
Authors M. Sarginson and T. KiviorSummaryReview of fault seal in Sabah deep water fields. Examples of static fault seals controlling hydrocarbon distribution, and fault baffles affecting field production performance are presented.
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Reservoir Properties Of Proximal To Distal Deep Water Turbidites — Sabah, Malaysia
Authors H. A. Ghaffar, T. Prasetyo, G. Henderson, D. Stanbrook and M. SarginsonSummaryHydrocarbons in deep water Sabah are reservoired within an approximately 500m thick sequence of Late Miocene (H110 to H160) turbidite lobes that are interspersed with mass transport deposits. These deep water clastic sandstone reservoirs vary in thickness and reservoir quality, which impacts prospectivity across several fields spanning 45km along depositional dip from a proximal to distal setting. In this paper we investigate the factors controlling reservoir properties and diagenesis in a proximal to distal turbidite depositional environment in the deep-water Sabah Baram Delta province.
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A Geomechanics-Based Solution To Decipher Salt-Related Deformation In Lower Congo
Authors X. Legrand and J. ShahSummaryPost-salt reservoir targets are a major focus for oil and gas exploration in passive margins with much consideration directed to lower part of Post-Rift Sequence. At reservoir scale, the entrapment structural style is closely linked to Salt which is considered as a visco-plastic layer and high variation of the paleo-topographic profile. Moreover, the quality of seismic imaging around thick and complex salt bodies is poor. Therefore, an innovative method using a geomechanics based restoration to refine the structural interpretation was proposed to decipher the complex salt-related deformation process and was used in Lower Congo Basin. The refined geological model highlights different structural styles governed by two main components that are the salt thickness and the detachment slope. The identification of gliding and spreading in gravity driven forces was demonstrated to be a good indicator to assess structural traps in otherwise complexly deformed the post-salt sediments.
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Deciphering Deformation History Of Overturned Strata Along A West Crocker Formation Outcrop (Ne Borneo, Malaysia)
Authors C. Giraldo and J. ShahSummaryIn order, to unravel deformation history of the overturned strata a systematic procedure has been followed: Unfolding strata back to normal position and restoring them using a 2D geomechanics software. Faults formerly considered as strike-slips and thrust faults contemporaneous to Miocene Borneo orogeny here they would be interpreted as syn-sedimentary gravity-driven deformations which suggests an Oligocene-Miocene in age and contemporaneous to West Crocker Formation sedimentation.
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Repeat Logging Using Distributed Acoustic Sensors And Earthquakes
Authors R. Pevzner, B. Gurevich, K. Tertyshnikov, A. Pirogova and S. GlubokovskikhSummaryRepeat downhole measurements of elastic properties would be extremely valuable for constraining 4D seismic inversion. However, intervention into wells to conduct such measurements is difficult and, in rarely used in practice. Distributed fiber optic sensing allows monitoring changes of formation properties, which could affect properties of the fiber-optic sensor: alter refractive index, cause physical deformation or the way the laser pulse is scattered. DAS is already often used to monitor production noise, microseismic activity and used as a sensor in 4D VSP surveys. In this presentation we demonstrate how distributed acoustic sensing could be used to monitor changes in elastic properties of the formation by monitoring local changes in seismic wave amplitude.
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Avo Analysis Using Walkaway Vsp In Offshore Malaysia: A Case Study
Authors N.L. Rafiuddin, S. Mohamed Taha and S. Saad ElkurdySummaryThis study aims to analyse AVO effect at the reservoir levels using common receiver gathers from a walkaway VSP. We present a step-by-step approach for seismic interpreters to further leverage on their VSP data, beyond the common time-to-depth relationship. The result of this study is an analysis of the reflectivity, R, with incidence angle θ, as well as intercept and gradient values. Results show that we have varying intercept and gradient values for two orthogonal source lines, which demonstrates the influence of anisotropy towards the AVO.
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Matching Pursuit Fourier Interpolation Of Borehole Seismic Data And It Is Application In Multi Offset Vsp Imaging
Authors F. Exton, K. Galybin, B.J. Lim and S. MoriceSummaryThis paper provides a description of the integrated approach of borehole geophysics together with surface seismic workflow practice, which is implemented to achieve beyond of conventional processing technique to derive the 2D reflection Image. This approach maximized the value of the existing intermediate VSP section which was acquired sparsely, by interpolating the “gaps” with seismic wavefield.
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Joint Imaging Of 3D Fiber Optic Das Vsp And Obn To Solve Shallow Gas Cloud Problem In Bokor Field Malaysia
Authors M.F. Abdul Rahim, A.R. Ghazali and M.D. DavisSummaryIn this paper we implement a Joint Imaging of the 3D fiber optic DAS VSP and OBN to improve imaging below gas cloud to enable better reservoir characterization. This survey simultaneously acquired 3D seabed nodal seismic and 3D Distributed Acoustic Sensing (DAS) Vertical Seismic Profiles (VSP) using fiber optic in three adjacent deviated offshore production wells. Production was not suspended during the VSP acquisition, so the resulting data was contaminated with production “noise” which varies with depth and over time. From the joint imaging results, better delineation of faults and reflector continuity can be seen in areas previously effected by the shallow gas cloud. The VSP data has a higher bandwidth at reservoir level compared to the OBN dataset.
This could be attributed to the undershooting below the gas cloud and proximity of the VSP receivers to the reservoir.
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Application Of The Play Based Exploration Workflow To Predict Source Rock And Reservoir Sequences In The Synrift Section Of Continental Rift Basins
By R. ShoupSummaryThe synrift section is a wholly contained petroleum system in continental rift basins. The foundational element of the petroleum system is the source rock. The distribution of the source rock and reservoir facies in a continental rift basin are controlled by climatic factors and the geometry of the rift basin. There are three archtypical rift basin geometries, asymmetric half grabens, symmetric grabens, and compound rift basins. The stratigraphic succession of the synrift section in continental rift basins typically exhibit eight sedimentary depositional environments. The lateral and vertical distributions of these depositional environments are remarkably similar from basin to basin and therefore offer a predictive model for defining the source rock and reservoir sequences. There are two source rock facies in continental rift basins, algal-rich lacustrine shales and more humic-rich shales deposited in swamp environments. These source–prone facies are generally found near the deepest portion of the basin and the asymmetric basin flanks. Reservoir facies are found in fluvial, delta and shoreface, and fan delta sequences, as well as the transitional red bed sequence that overlies many continental rift basins.
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A Strategy To Reduce Dry Holes By 25 To 50%
By R. ShoupSummaryThis paper will examine the principal causes of dry holes and will present a two-part strategy that companies can implement to reduce the number of dry holes they drill . Conducting pre-drill audits can reduce your dry holes by 25 to 50% Studies have shown that approximately half of the dry holes that were drilled were dry due to failure of the trap or seal Audits of the maps that were the basis for drilling the well indicate that the majority of wells attributed to trap or seal failure were actually drilled on invalid structure maps Conducting regional reviews or mentoring sessions can further reduce your dry holes Although it will be virtually impossible to eliminate all dry holes, conducting regional reviews or conducting mentoring sessions with your interpreters will hold them accountable for understanding the petroleum system. Mentoring sessions allow your staff to benefit from the knowledge of experts who can bring a fresh perspective and new insights to help your interpreters better understand of the petroleum system, and improve their maps and evaluations, helping you reduce risk and improving your exploration drilling success.
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High But Unrecognized Potential In Permian Carbonates Of Southeast Asia
Authors F. Xue and T. KanitthornSummaryPermian carbonates have very high hydrocarbon potential in Southeast Asia. At first, they have very high single-well productivity, up to MMBOs and hundreds of BCFG in cumulative. Secondly, they have thick and extensive distribution through much of the Southeast Asia. They consist the basement plays under Mesozoic basins in onshore areas represented by Sinphuhorm Field and under Cenozoic basins in offshore areas represented by Nang Nuan Field. But E&P in this play has been not successful due to the limited knowledge on the extreme and extensive heterogeneity in Permian carbonate. The advance carbonate reservoir characterization in these two field has illustrated that large cavities (caves) are the main contributor to the high productivity and their uneven distribution in tight matrix leads to highly uneven distribution of reserves and productivity in carbonate reservoirs. The surface and subsurface G&G data has illustrated that caverns are widely distributed in both orogeny and basin provinces of Southeast Asia. With proper knowledge and approach, Permian carbonates will become an important play in Asia petroleum E&P.
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Subsurface Reservoirs Imaging Through Characterization And 3D Modeling
More LessSummaryPresentation of an integrated modeling workflow that take in account all of the available data (static and dynamic) to build a 3D integrated geological model for the subsurface reservoir.
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Cased Hole Saturation Logging To Identify Bypassed Oil Opportunities - Case Studies From The Sarawak Basin
Authors A. Griffin, R. Gunarto, S.H. Zamridin and S. AlawiyahSummaryMurphy Oil Company operates a number of mature oil and gas fields in the Sarawak Basin, Malaysia. It has been utilizing a new generation pulsed neutron tool (“PNT”) to help track production related fluid changes and identify bypassed oil. This paper summarizes case studies from 2 wells, using the PNT tool for saturation logging and interpretation, and the production benefits identified. Field A results include the identification of a displaced gas-leg and a basal swept zone. The well was successfully recompleted in the original gas-leg with production of 1000 BOPD and low GOR. Limited water production commenced several months later, consistent with the PNT results. Oil movement to the gas cap was identified accurately using the PNT log as confirmed by well testing and production. Field B was logged over 3 reservoirs and two recompletion targets were identified. Reservoir B1 has a full oil-leg below the original GOC with no evidence of water-sweep. Reservoir B2 is thin-bedded with ambiguous hydrocarbon fill; logging results indicate that this zone is oil-bearing. It is planned to complete both zones as oil producers utilizing a single production string configuration with zonal selectivity, increasing field production and accessing additional, previously undeveloped, reserves.
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Integration Of Stochastic Inversion And Rock Physics To Detect The Upper Miocene Thin Gas Sand In The Nam Con Son Basin, Vietnam
More LessSummaryThe Nam Con Son (NCS) basin is the second ranked in term of HC reserve in Vietnam after the Cuu Long basin. To find out more clastic reservoir zone, in particular the thin gas sands, is a need as the oil production from the main contributor of fractured granite basement is more and more reduced. In this study, integration of stochastic inversion and rock physic cross-plotting results could enable to highlight a thin gas sand in seismic section in Upper Miocene, which might be easily missing in a normal seismic interpretation. It is recommended such an integrated method can be tested and applied more in exploration practice in the NCS basin, Vietnam.
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Mitigation Of Structural Uncertainty In High Angled Dipping Middle Marrat Reservoirs With The Help Of Deep Electro-Magnetic Inversion Geosteering Technique, Calibrating With Seismic Data- A Case Study, Umm Gudair Field, West Kuwait
Authors D. SinghaRay, A. Al Shemali, R. Quttainah, N. Al Mutairi, S. Noreldeen and C. KeotSummaryMarrat Jurassic reservoir in Umm Gudair Field, West Kuwait is characterized as deep and tight carbonate limestone reservoir. Most vertical wells are low producers due to poor reservoir properties in addition to the reservoir pressure depletion. In order to enhance Middle Marrat reservoir productivity, the practice of horizontal drilling is being adopted. However, boundary navigation and optimizing the drainhole within the desired target layer poses the biggest challenge in this regard.
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An Integrated Approach For Acidising Job Design Via Rapid Mineralogy Analysis
Authors H.X. Dan, N.S. Sadan, L.C. Chisholm, A.M. Abu Bakar and D. BurkettSummaryThe study scope was to identify a compatible acid type for removing HEC Pills (LCM materials) and to formulate non-damaging acid systems to the specific formation mineralogy. In order to complete this, the mineralogy of the targeted reservoirs would be required to identify the presence of any unstable clay types which would react with acid. Some of the petrographic study results from major reservoirs that had core taken showed abundant presence of unstable clay types, such as chlorite and mica. Due to the absence of conventional core for the undeveloped reservoirs, cuttings were instead used and petrographic studies were carried out. Due to the constrained timeline the project team opted for mineralogical analysis using a portable X-ray diffraction (XRD) instrument. The results would later be compared with traditional laboratory powdered XRD analysis which determine the types and quantitative bulk composition of clays present in the sample. As petrographic studies are dependent on sample preparation, some variations in qualitative and quantitative mineralogy were observed between petrographic analysis and XRD analysis. Nevertheless, portable XRD was able to identify the presence of similar minerals with rapid analysis and this could be adapted for potential wellsite use in the future.
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Dual-Ing With Julimar: An Innovative Approach To Develop A Stacked Reservoir System
Authors C. Fields, Z. Dholkawala, S. Bunton, M. Roets, M. Wallwork, N. Mews, H.M. Lee, U. Wong, L. Abbott and S. BeecroftSummaryThis presentation discusses the Julimar Development Project (Julimar and Brunello gas fields), in particular, Phase 2. This proposed phase of development includes four intelligently controlled, dual zone open-hole gravel pack wells. This is the first application of this technology in gas wells globally.
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Improved 3D Anisotropic Csem Cross Gradient Structural Inversion Incorporating Resistivity Logs And Seismic Horizons
Authors M.A. Meju, A.S. Saleh, R.L. Mackie and F. MiorelliSummaryCross-gradient constraint is used in 3D anisotropic resisitivity inversion to improve structural similarity between horizontal and vertical resistivity models. The methodology has been tested at controlled field-site in a deepwater fold-thrust belt geological environment with encouraging result.
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Multi-Physics Workflows For Quantitative Interpretation Of Seismic And Csem Data
Authors L. MacGregor, K. Nichols, J. Tomlinson and R. KeirsteadSummaryIt is well known that combining multiple geophysical data types in rock physics-driven multi-physics workflows can improve the robustness of reservoir property estimations. For example, the integration of prestack seismic inversion attributes with controlled source electromagnetic (CSEM) data has been shown to dramatically improve the certainty with which commercial hydrocarbon saturations can be distinguished from reservoirs containing only residual saturation, a problem that is hard to address with seismic methods alone. However there are many approaches to multi-physics analysis. The choice of approach depends on the data available and the geophysical objective of the analysis. Here we present a staged workflow for quantitative characterisation of reservoir properties using seismic and CSEM derived attributes.
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Gravity And Subsidence Monitoring For Production Optimization And Improved Reserve Estimation Of Gas Fields
By O. EikenSummarySurface gravity and subsidence monitoring for improved reservoir management are rapidly developing. On land sub-cm precision can be obtained with various techniques, and at the seafloor by using water pressure measurements. The surface movements are mostly caused by changes in fluid pressure and can be inverted for the product of reservoir pressure change and compressibility. Gravity monitoring is now routinely done with a precision of 1–2 µGal. The low density of gas makes water influx in gas reservoirs a primary goal for gravity monitoring. Combining reservoir pressure with gravity data, the remaining gas will be better determined.
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Characterization Of Basement Reservoir Lithology Using Mineralogical And Geochemical Approach: Example From Malay Basin
Authors S.N. Cheng, N. Pendkar, M.R. Anuar, R. Danial, R. Roslan, C. Magnier and V. TharmalingamSummaryThe known plays in the Malay Basin has been well explored, developed, and produced with the exception of ‘fractured basement’ which still remains underexplored. Wells drilled to-date into the fractured basement in the Malay Basin yielded variable results.
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Role Of Seismic Attributes In Reserve Estimation
Authors R.A. Mohamed Ghozali, A.T. Patrick Panting, N. Zakaria and H.N. NguyenSummaryIn Oil & Gas - Exploration and Development endeavors, there is no doubt that seismic data plays a huge and important role. In fact, it is considered to be the primary tool when we attempt to understand what we have in the subsurface. Seismic data however, is not that simple and has its own limitations. Seismic resolution for example is important to seismic interpreters and knowing the tuning thickness will help us know how much of the reservoir can be imaged vertically. In cases of low resolution, the thinner bed might not be imaged or can be seen only partially, causing the thin hydrocarbon bearing reservoirs to go undetected or unnoticed during seismic interpretation. The aim of this paper is to demonstrate using a case study from the Malay Basin, how seismic attributes may help in interpretation and identifying reservoir boundaries in areas below the tuning thickness and where interference from the above bed causes more challenges.
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Facies-Based Inversion Through The Asset Lifecycle
By S.K. ChengSummarySeismic lacks low frequencies, so for an absolute seismic inversion (which allows us to be quantitative!) a so-called Low Frequency Model (LFM) is required. Starting from an empty LFM, we would of course like to post Sand Vp values where there is Sand, Shale Vp values where there is Shale, etc. (for a minimum of 3 impedances and for all facies expected).
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Streamlining Petrophysical Workflows With Machine Learning
Authors L. MacGregor, R. Keirstead, N. Brown, A. Roubickova, I. Lampaki, J. Berrizbeitia and M. EllisSummaryThe oil and gas industry is not short of data, in the form of wells, seismic and other geophysical information. However, often because of the complexity of workflows and the time taken to execute them, only a fraction of this information is utilized. Making better use of information, using modern data analytics techniques, and presenting this information in a way that is immediately useful to geologists and decision makers has the potential to dramatically reduce time to decision and the quality of the decision that is made. Here we concentrate on using machine learning approaches to streamline petrophysical workflows. However, to do this requires a rich and diverse training dataset of wells that have been consistently processed for geophysical analysis. The work discussed in this paper has focused on the estimation of clay volume, determination of mineral volumes and determination of porosity and water saturation. A variety of machine learning techniques and algorithms have been tested to find the one most suited to this application. Initial analysis is regionally focused, but we plan to investigate whether the approaches and models developed can be generalized across regions, basins and geological settings.
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Elasticdocs As An Automated Information Retrieval Platform for Unstructured Reservoir Data Utilizing A Sequence Of Smart Machine Learning Methods Within A Hybrid Cloud Container
Authors N.M. Hernandez, P.J. Lucanas, I. Panganiban, C. Mamador and C. YuSummaryThere is a tremendous amount of information available and stored in digital geoscientific documents and published reports in the energy industry. These documents contain a distillation of reservoir information from diverse discipline of geologists, geophysicists, petrophysicists and drillers, that are stored in unstructured format, which find further use in succeeding reservoir modeling stages. In particular, national data management repositories and oil companies hosts these huge amounts of historical well reports containing information such as lithology, hydrocarbon shows, and other reservoir data. Due to the large volume, vintage variety, and non-standardized formats, extraction of valuable information that are used as inputs for interpretation, is an arduous, very time-consuming task. Our solution is to develop ElasticDocs a machine learning-enabled platform in a hybrid cloud container that automatically reads and understand hundreds or thousand of technical documents with little human supervision through a smart combination of machine learning algorithms including optical character recognition (OCR), elatic search, natural language processing (NLP), clustering and deep convolutional neural network. The platform uses a hybrid, 2-tier data service architecture leveraging on the strength of both the strength of local servers and cloud to enhance data security, integrity, and accessibility.
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Seismic Multi-Attribute Volume Classification: Case Study From Malaysian Reservoir
Authors M.M. Jalil, Y. Khairil Amin, S. Isa and H. OthmanSummaryIn complex reservoir, individual seismic attributes are usually insufficient to delineate in detail stratigraphic features of a specific target. Seismic Multi Attributes Pattern Recognition or “SMART” is an advanced techniques for application in reservoir study. Generating supervised and unsupervised classified maps through seismic pattern recognition provides and effective method to map stratigraphic features. It reveals details of underlying geologic features and help in the interpretation of facies changes in reservoirs.
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Litho-Fluid Characterisation Of Fluvio-Deltaic Gas Reservoirs Through Ava Deterministic And Stochastic Seismic Inversion
By A. ContrerasSummaryA state-of-the-art Amplitude-versus-Angle (AVA) inversion methodology is described in this case study to quantitatively integrate partially-stacked seismic data, well logs, geologic data and geostatistical information. Deterministic and stochastic inversion algorithms are used to characterise Intra-Triassic Mungaroo gas reservoirs located in the Carnarvon Basin, Western Australia. AVA deterministic and stochastic inversions, which combine the advantages of AVA analysis with those of seismic inversion, have provided quantitative information about the lateral continuity of the Fluvio-Deltaic reservoirs as well as the delineation of the gas reservoirs, based on the interpretation of inverted elastic properties and lithology and fluid-sensitive modulus attributes. AVA stochastic inversion provides more realistic and higher-resolution results than those obtained from analogous deterministic techniques and allows for uncertainty analysis. The quantitative use of rock/fluid information through AVA seismic data, coupled with the co-simulation of elastic/petrophysical properties, provides accurate 3D models of engineering properties such as porosity, volume of shale, and water saturation which can be directly used for static model building.
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Fine Scale Clastic Reservoir Characterisation And Uncertainty Quantification—A Case Study Offshore Sarawak
Authors R. Doshi, N. Vargas, O. Colnard, S. Saad El Kurdy, A.L. Yahya and C.K. TanSummaryThis paper presents a stochastic inversion case study carried out on a mature field, offshore Sarawak. This study is an attempt to overcome a few data limitations. Firstly, the resolution of the seismic data at the target depth is well above the required resolution of 5–10 m. Secondly, localised poor quality pockets in the seismic data created uncertainties in the well depth to time relationship. Also, an initial test of stochastic inversion showed that the number of surfaces required to constrain the target interval were not sufficient and created incorrect geobodies. This paper details how these issues were addressed.
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Application Of Seismic Inversion Workflow Guided By Depth-Dependent Rock Physics Trends: A Qi Study In Pm-3 Caa
More LessSummaryApplication of Seismic Inversion Workflow Guided by Depth-dependent Rock Physics Trends: A QI study in PM-3 CAA
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Reviving Un-Tapped Potential In A Brown Field Through Geophysical And Reservoir Model Evaluation
Authors N.A. Mohamad Radzi, R. Hardiani, M.Z. Zamanshah, A.H. Mustafa, A. Khalil, Z. Ishak and A. RoySummaryThis paper will demonstrate the best practices in Geophysical and Reservoir Model Evaluation for identifying remaining untapped oil opportunities. A 4-Component 3-Dimensional Ocean Bottom Cable (4C 3D OBC) seismic survey was acquired in 2015 and was used as input in building the reservoir model and used for identifying the remaining oil location in a brown field in Field Tango. This led to a more advanced management through placement of water injection, infill wells and new oil producers in this field to sustain and increase production.
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Which Fault Matters: Evaluation Of Reservoir Compartmentalisation By Integration Of Borehole Image And Real-Time Isotope Data Δ13C1
Authors N. Ha, C. Murlidhar, A. Brem, V. Vevakanandan and T.T. ZhangSummaryShell Malaysia has drilled 11 development wells targeting two reservoirs (R1 and R2) in a Deepwater Field (M field) offshore North West Borneo. M field is a complex faulted 4-way dip closure, comprising a turbiditic depositional environment.
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Linking The Diagenetic Evolution To Poroperm Development In A Paleozoic Carbonate Reservoir Analog, Northern Vietnam
Authors H.A. Nguyen, T.A. Vu, T.T.T. Tran and T.S. NguyenSummaryA lot of exploration wells have been drilled to test “buried-hill” plays in fractured Paleozoic carbonates in offshore northern Vietnam with either dry holes or showing low flow rates. To better understand diagenesis-related poroperm development and how can we target more successfully in this complicated reservoir, a detailed geological characterization of fractured Paleozoic carbonates was undertaken in a quarry outcrop in the Northern Vietnam. This work integrates the results of detailed mapping and interpretation of lithologies and fracture orientations, along with detailed petrographic and isotopic analyses and leads to the following conclusions: (1) Significant levels of poroperm in fractured Paleozoic carbonates in the region are mostly confined to NE-SW fracture sets created and enlarged in the telogenetic realm relating to uplift in a stress field created by movement of the Red River Fault. (2) Equivalents to this style of diagenesis likely occur in subsurface as potential fractured Paleozoic reservoirs in the nearby offshore. (3) Successfully exploring and developing such reservoirs will require directional (not vertical) wells and a better rock-based understanding of the controls, orientations, timings of major fracture events (requires outcrop and core-calibrated FMI interpretation). (4) Poroperm predictions in subsurface counterparts require an improved understanding of fluid evolution and the relative timing of the various diagenetic events that can occlude or enhance porosity and permeability in both matrix and fractures (requires detailed petrographic study tied to texture-aware isotope sampling of cuttings or core).
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Controlling Factors For Reservoir Quality In East Balingian, Sarawak
Authors A. Noorhashima and T. PrasetyoSummaryThis study aims to understand the controls of the reservoir quality in the East Balingian, Sarawak. Data integration from cores and cuttings (petrography, XRD, porosity & permeability) as well as temperature and pressure data from 23 wells are used. The result observed that most of the wells show porosity reductions (going less than 10%) starting at 2000–2500 mSS and this serves as the crictical depth for porosity preservation in the study area. It was found that this reduction in reservoir quality are affected by mechanical compaction, overpressure, chemical compaction (temperature & diagenesis) and facies grain sizes and clay content. The improved understanding gained from this study is hoped to be used as a guide for near future exploration campaign in the less explored areas in East Balingian basin.
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3D Paleo-Environmental Facies And Petrophysical Properties Of Mangahewa Formation, Maui Gas Field, New Zealand
By A.E. HAQUESummaryMaui Gas Field is the largest producing field in New Zealand having Mangahewa Formation as the thickest reservoir of this field. According to the study Marginal marine was interpreted to be the dominant depositional environment of the formation as a whole having about 64% of depo-facies; whereas shallow marine environment comprised about 29% and offshore comprises 7% of the depo-facies modeled within the Mangahewa Formation, Maui Gas Field. Paleoshoreline reconstruction of the facies modeled that ttransgression occurred from older deeper to the younger shallower layers within the model. Paleoshoreline was interpreted to have a broad North-East to South-West trend within the model along with their internal migration over time.
Whereas the petrophysical model of the formation correlated positively with the paleo-depositional model and petrophysical maps of Mangahewa reservoir parameters reveal that, the most favourable location for the producing reservoir is the east-central part of the gas field.
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Successful Integration Of Sampling While Drilling And Geomechanical Analysis In Unconsolidated Reservoir: A Case Study From Sarawak, Malaysia
Authors I.L.T. Ong, A.K.L. Ng, N. Hardikar, A. Khalid, J. Pragt, A. Khaksar and F. AdegbolaSummaryFirst LWD water sampling work in Malaysia
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Geomechanical Modeling Of Thermal Effects On Pore Pressure Prediction And Wellbore Stability In Hpht Wells
Authors A. Chatterjee, A. Ghosh and S. BordoloiSummaryThe integration of geomechanical modeling with understanding of geological control on overpressure mechanism helped the well designer sets his/her expectations in the planning phase, enabling a more proactive approach for flawless execution during the drilling phase. The well was successfully drilled to the desired depth despite a predicted drilling margin of only ∼1.0 ppg, reducing non-productive time (NPT).
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Accurate Geomechanical Sanding Prediction, Two Case Studies From Offshore South And South East Asia With Years Of Production
By A. KhaksarSummaryThis presentation highlights the essential elements of an integrated sand management approach with a focus on geomechanical sanding risk evaluation for sand control and completion decisions. The presentation will include two recent case studies from offshore South East and South Asia with different geological settings and well operation conditions, both with several years of production history and observations. The two case studies demonstrate the validity of geomechanical assessments conducted at early field life that are verified later following 10–15 years of hydrocarbon production with different outcomes and observations.
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Geology To Geomechanics Integrated Workflow For Better Production Risk Management
Authors C. Cosson, S. Ducroux and L. Van den BrulSummaryComprehensive geomechanical studies are key to mitigate risks from in-situ stress changes due to oilfield drilling, completions and production operations. Today however, most geomechanical models used in these studies lack the geological integrity required to derive reliable decisions. One major contributor to this limitation is the alterations to data and assumptions as they get passed from one discipline to another; very often a symptom of a poor cross-domain collaboration. A geomechanical specialist for example gets his input 3D model from the reservoir engineer, but operates usually independently from the geophysicist or the geologist who interpreted the initial data. This disconnect between disciplines is seen as both a work culture problem and a technology problem. This paper will address the technology aspect by introducing new advancements to geomechanical workflow integration through the use of a shared structural model. This model is constructed by honouring available data without unwarranted simplifications. It is then used by geoscientists across the board including geophysicists, geologists, reservoir engineers and geomechanical specialists to derive fit-for-purpose and consistent numerical models. For the geomechanical workflow, structured and unstructured grids are created directly from the shared structural model honouring all interpreted structural and stratigraphic features critical for a proper assessment of stress changes in the Reservoir.
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State Of The Art In Petrophysical Modeling Of Low Resistive Low Contrast Pays (Lrlc) Using Ideal Resistivity Model
By H. HassaniSummaryNowadays Low Resistive Low Contrast pays (LRLC) are forefront of mature-field secondary objectives where production from conventional reservoirs get lesser and lesser. Although LRLC reservoirs have been under production for many years, knowing reservoir complexity mainly at volume and flow capacities are still big challenges. Lithology is one of the element, which can carry some portion of reservoir complexity. Among the possible scenarios, shale plays a different role; Understanding the shale behavior and its distribution patterns is a key to improve the reservoir characterization and consequently unlock potential unseen volumes. In the absence of a well defined distribution model, an integrated approach of forward modeling and inversion is also impractical for the accurate evaluation. Majority of conventional approaches unable to address reservoir complexity due to log resolution constrains. This paper aims to introduce new approach, as a tool, to qualitatively determine thin-bedded sand characteristics, which can be used as an integral part of low-resistive techniques. It implements ideal resistivity-base model (RT-Model) to evaluate shale distribution in clastic reservoirs. The process couples the deep resistivity with gamma ray measurements in new laminar gauge to properly determine not only corrected shale volume but also distribution pattern independent of advance log measurements. Based on the result the method is able to quantify bed thickness smaller than a feet (2 to 4 in) that is actually beyond conventional log resolution. Corrected shale volume and sand resistivity are main products while net sand porosity and fluid saturation are secondary products derive through workflow optimization practices and uses inputs from new lamination model. Resistivity-base porosity shows better consistency with core data where traditional approach failed to match core trend in highly laminated section.
Outcomes has been finally verified with hard evidences and direct measurements like image log, production profiles and core data. Compression shows encouraging results at both well and field scales. At well level, RT-Model products has been fully align with direct measurements and at field scale, results have been fully supported by dynamic model where enhanced volume and flow capacity from RT-Model are closely tied with expectation from the model.
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An Industry First: Successful Formation Sampling while Drilling (Fswd) Under Pressurized Mud Cap Drilling (Pmcd)
Authors C. Shield, D. McKinney, N. Hardikar, M. Dulam, I. Kim, J. Pragt and F. AdegbolaSummaryThis paper describes the successful deployment, sampling and calibration of formation sampling while drilling (FSWD) under total losses and pressurized mud cap drilling conditions (PMCD); an industry first. The successful results emanate from excellent collaboration between well engineering, sub-surface, and third-party technology providers. LWD fluid sampling is traditionally applied for complex wellbore geometries, but in this case it is applied for difficult reservoirs that often contain karsts resulting in total losses. PMCD is a drilling technique commonly applied in these conditions and requires seawater to be pumped down the drill pipe with a light water-based mud on the backside for pressure control. Pre-job planning and operational procedures that resulted in the successful collection of gas samples will be discussed. The LWD fluid sample quality and gas contamination levels were confirmed by comparison with reference wireline fluid samples that were acquired in the ensuing side-tracked wellbore. Samples were found to be comparable in gas composition, OBM filtrate contamination, and H2S, CO2, and N2 levels. This study extends earlier work and confirms the validity of FSWD for H2S contamination accuracy in high H2S and very low H2S cases. Further studies are required to complete the calibration for low-level H2S reservoirs.
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Delivering A Horizontal Well In A Complex And Highly Faulted Reservoir Using Novel Data Acquisition Techniques
Authors V. Vevakanandan, T. Zhang, A. Ting, D. Mckinney, N. Ha and C. MurlidharSummaryThe M field is a complex faulted anticline structure occupied by 80–100ft of oil column in laminated sand shale formations, of which individual beds are typically below log resolution. The Phase 1 Development campaign targeted 2 reservoirs for production, the R1 and the R2 reservoir, both of which show a fining upwards stratigraphy. The reservoir is characterized by seismically mapped faults with throws up to 60 ft. Pre-production concerns were that these faults would be sealing on a production time scale, thus efficient sweep and ultimate recoveries were a major uncertainty. To maximize reservoir penetration and increase the productive intervals whilst avoiding damaging the production interval with excessive casing shoe penetration, 2 horizontal wells were designed to be optimally placed within the better-quality sands. To have the well straddle across different fault blocks, without having shales exposed and risk shale swelling and dispersion, the data acquisition strategy was designed to include novel technology that could characterize faults real time and assist the team in making informed decisions during drilling.
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Rejuvenate The Low Resistivity Pay Sand To Capture The Potential On Sarawak, Malaysia
Authors M.S. Ahmad Kassim and W.A. TolioeSummaryNowadays, the oil and gas companies still invest on exploration activity and expected to discover new reserves which can be developed to meet domestic and international needs. The oil and gas discovery has to meet the economic critera and be able to be developed. The upside potential, such as, the low resistivity-low contrast reservoir, can add the value to economic criteria by optimizing the hydrocarbon in-place. These kind of reservoirs were not as primary exploration target, but once the hydrocarbon was shown on this kind of reservoir, it needs to be evaluated with special and integrated analysis and should be included the in-place calculation. The low resistivty of thin laminated reservoirs is quite challenging to be determined on the first phase and comprehensive data acquisition need to be planned well. The low resistivity responses of this lamination shaly- sand reservoirs will lead the evaluation and assessment to be water bearing zone, especially by applying the conventional approach, although the hard data determine that zone as hydrocarbon bearing zone. Hence, more data needed to be used such as Nuclear Magnetic Resonance (NMR), Image log, Pressure and Sample is crucial for the interpretation. This data also help to solve any difficulty faces for normal reservoir
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De-Risking The Reservoir By Attenuating Interbed Multiples
Authors L. Do Hoang, C. Lam Choong, M.L. Ghazali, A. Bisset and S.L. AlfredSummaryInterbed Multiples can lead to spurious interpretation of primary reflection. Removal of these types of multiples is not properly handled by conventional demultiple techniques. In this case study, we will demonstrate application of Interbed Multiple Attenuation using Inverse Scattering Series Method (ISS-IMA). The result of Interbed Multiples Attenuation from the example shows a significant uplift in imaging clarity at reservoir level.
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Integration Of High Resolution Fwi Velocity Model And Broadband Data For Elastic Property Generation: A Low Frequency Overlap Case Study In The Norwegian Sea
Authors C. Reiser, T. Martin, A. Long, S. Naumann and D. CavalinSummaryObtaining absolute elastic attributes for lithology and fluid prediction requires a low frequency model. This was achieved by collocated co-kriging of seismic velocity and well information. Increasing the bandwidth with broadband seismic only requires a low frequency model for the 0 to 3 Hz range, reducing emphasis on the well information. Less a priori input is advantageous in attribute prediction; the results of pre-stack seismic inversion are primarily data driven. Full waveform inversion (FWI) creates high resolution velocity models. Both high resolution FWI models and broadband seismic data can provide the low frequency component of elastic property generation enabling well information to be a control point; Reservoir geoscientists can confidentially derive reliable elastic attributes such as acoustic impedance and Vp/Vs ratios away from the well locations. We present the results of a study varying the overlap point between a full wavefield FWI model and broadband seismic in an absolute elastic inversion and draw conclusions on the optimal data use for a volume from the Norwegian Sea.
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Multi-Survey Q-Fwi Enables Imaging Uplift And Robust Time-To-Depth Conversion In Deep Water Sabah Fi
Authors V. Goh, T.C. Hor, H. Van Voorst Vader, H. Dols, A. Tan, K. Mohamed and A. Jose VizamoraSummaryThe M field is a deep-water field in Sabah, Malaysia, in early stages of production. The field, composed of multiple turbidite reservoirs, is considered structurally complex heavily faulted and compartmentalised, and underlie a rugose sea bottom and complex overburden with presence of gas. After the first development phase, the velocity model was assessed against data acquired during drilling, e.g. well logs and other well-based information. Vertical incidence VSPs acquired in deviated and S-shaped wells indicated that the lateral velocity variations within the overburden is larger than previously modelled, due to a complex overburden. Further refinement of the velocity model is essential for further development planning, reservoir management, and updates to resource estimation.
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Full Wavefield Migration For Solving Gas Cloud Imaging: A Field Example
Authors M.H. Mad Zahir, A.R. Ghazali, S. Mad Sahad and M.A. IshakSummaryThe South East Asian offshore basin, were known to be prone of shallow gas accumulation. There are many imaging method being discussed to compensate the shallow anomalies so-called ‘gas clouds’ or ‘gas chimneys’ (Ghosh et al, 2010). PETRONAS has been successful in obtaining better seismic image below gas clouds (Akalin et al, 2010; El-Kady et al., 2012). However, almost every conventional imaging method are based on using primaries only, thus having less optimized estimation of the true reflectivities below gas cloud. Here, we believes that the multiple scattered energy from the gas cloud carries additional information that could provide ‘almost true amplitude’ reflectivities below gas cloud.
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A Novel Analytical Approach To Estimate Sand Production In Unconsolidated Reservoir: Case Study And Validation In Oil Field “N”
Authors D. Arianti, D. Septariany and S. Pheronica RanaSummarySand production is the migration of formation sand caused by the flow of reservoir fluids. This paper aims to develop an analytical model to predict sand production in oil field and validate it using 4 wells in Field “N”. Coupled sand failure mechanism considering static and dynamic criteria is used to models sand production. Rock particles strength is predominantly acting by drag and buoyancy forces, while sand particles are assumed as spherical and submerged when flowing. To capture fluid flow and pressure drop in porous medium, Darcy’s law is applied. The proposed analytical equation successfully models sand prediction accurately in 4 wells at range of cavity height 12–25 ft. At oil rate 1000 STB/day, calculated sand production in Well 1 is 0.005 lb/bbl, Well 2 is 0.007 lb/bbl, Well 3 is 0.005 lb/bbl, and Well 4 is 0.002 lb/bbl. Comparing to the field data in 4 wells, only 3% of analytical method to real data discrepancy is achieved.Sensitivity studies are conducted and show that cavity height, oil rate, fluid viscosity, and sand grain size put most of influencing parameters to calculate sand production. This study suggests at low and moderate oil production rates, cavity height is applied at 10–25 ft.
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Application Of Acoustic Noise And Temperature Logs In Idle Well Restoration And Qualitative Assessment Of Reservoir Performance
By S. HamzahSummaryThis paper presents the application of the acoustic noise and temperature logs in idle well restorations in Field A, offshore Malaysia and how the data is further utilized to qualitatively assess reservoir performance. Key logging strategies for successful leak detection and log interpretation analysis under complex borehole and reservoir environment settings are discussed. These strategies include designing a proper logging program under multiple borehole conditions whilst monitoring the surface tubing and casing pressures, optimizing the stationary acoustic noise data acquisition, and integrating the acoustic noise, temperature and pressure data to qualitatively analyse reservoir performance.
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Brine Estimation In Shale Gas Reservoirs Using Wireline Logging And Laboratory Data: A Case Study From Murteree Shale, Cooper Basin, South Australia
Authors M. Ahmad, E. Padmanabhan, M. Haghighi and M. RajabiSummaryThe argillaceous nature of unconventional gas reservoirs presents ultra-complex lithology, nano-scale porosity and permeability. Petrophysical and mineralogical evaluation of these formations challenge high resolution diversified evaluation techniques to investigate first the dual storage mechanisms of natural gas and later to help in designing hydraulic fracturing techniques for maximum recovery of gas. Research work and contents in this paper are intended to develop some insight about post depositional diagenetic events in shale gas formations which have direct impact on brine evaluation in these types of overly clay rich reservoirs. Insights will help in understanding, reasons of uncertainties and doubts about controversial application of true formation resistivity (Rt) values from resistivity wireline logs in seconds Archie’s (1942) Equation in shale gas reservoir. Direct evaluation and assessment of porosity in shale is not reliable from wire-line logs alone; thus, it is essential that logs be calibrated with lab direct measurements such as QEMSCAN, XRD, and FIB/SEM. In the following sections, the geological background of study area is first discussed followed by our literature review and methodology used to determine different parameters for water saturation evaluation. Results are presented with the sensitivity study of different parameters. Some conclusive results are given at the end.
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