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APGCE 2019
- Conference date: October 29-30, 2019
- Location: Kuala Lumpur, Malaysia
- Published: 29 October 2019
99 results
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TERTIARY PALEOGEOGRAPHIC EVOLUTION OF THE SUNDA SHELF: IMPLICATIONS FOR EXPLORATION PLAY DEVELOPMENT
By R. ShoupSummaryPaleogeographic and depositional environment maps were constructed for the Lower, Middle, and Upper Oligocene and the Lower, Middle, and Upper Miocene. These illustrate the evolution of the Sunda shelf and provide a means to define the synrift and post-rift source rock potential of the various basins
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RESERVOIR EVALUATION: VANDJI FORMATION OF BERRIASIAN-VALANGINIANAGE IN LOWER CONGO BASIN
By N. TukiminSummaryLower Congo and South Gabon basin have seen many hydrocarbon successes since 1960’s. Recently, forgotten play in the lower rift section was revived with huge discovery in Lower Congo basin. This paper aims to provide a comprehensive reservoir analysis on one of the lower rift plays, Vandji Formation of Berriasian-Valanginian age in Lower Congo and South Gabon basin. Vandji Formation is deposited in the earliest stage of rift phase primarily in the basin between eastern and Atlantic Hinge as thick high energy alluvial and fluvial clastic sediments in lacustrine setting. This succession consists of conglomerate, fine to coarse grained sandstone. An analog of alluvial plain from Africa was used to better represent Vandji Gross Depositional Environment. Alluvial plain is generally 10–20km wide from basement highs and continents. The geometry of basement highs and shape of braided channel uses bouguer anomaly map as reference and consistent with wells that penetrated through braided channel facies. Rich well datasets of SEM, core data, mudlogs, electrical logs, reports and bouguer anomaly map were used to constrain the boundaries of gross depositional environment map for Vandji formations. Two models were established to capture the uncertainty between control points to investigate reservoir presence. Reservoir effectiveness was evaluated using porosity and permeability data to identify any correlation to the depositional environment. Vandji reservoir is perceived as poorly sorted and micropores are filled with interstitial clay such as illite filling the pore throat. Porosity depth trend for Vandji Formation shows high variability. Two trends were observed between alluvial plain and deltaic facies. This study also found that facies deposited in braided channel should belong to a different compaction curve. The wide range of porosity is also largely affected by diagenesis such as cementation, quartz overgrowth and clay filling. K-Phi trend shows that good permeability of more than 150mD seems to be attributed by intragranular dissolution pores associated with feldspars and deposited in high energy and constant movement creating void spaces. The porosity map is established underpinning isopach map between seabed-Top Vandji and most likely trend from porosity depth plot. Vandji reservoir quality is shown to have better porosity around basement highs with lower angle. Higher angle basement highs are more likely to erode and be deposited as alluvial plain.
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STRUCTURAL FRAMEWORK AND HYDROCARBON PLAYS IN THE PENYU BASIN, OFFSHORE PENINSULAR MALAYSIA
Authors M. Madon, J. Jong, F. Kessler and N. M. SharefSummaryThe Penyu Basin is moderately explored that may still have undiscovered hydrocarbon potential, and recent studies suggest that the basin remains prospective with excellent data coverage of both 2D and 3D seismic. The basin was formed in continental crust, although the exact origin is not properly understood and most authors generally considered it as a pull-apart or “rift-wrench” basin. This is supported by the presence of major strike-slip faults and associated normal faults as being the main basin-bounding faults. The initial half-graben basins evolved into isolated lacustrine systems that provide source-rock facies habitat that could potentially charge the traps in the syn-rift and post-rift sequences. Trap styles in the Penyu Basin include the compressional anticlines, basement drape structures and syn-rift stratigraphic/structural traps. The results of the syn-rift exploration are encouraging, albeit a detailed understanding of the reservoir distribution is essential for identifying future drilling targets in this interval. Undoubtedly, more detailed mapping of new structures with application of new techniques such as basin modeling, integrated structural and high-resolution potential field data interpretation will help in identifying new play types and enable a better understanding of the structural evolution and hydrocarbon prospectivity of the basin.
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IMPROVED MARINE SEISMIC SURVEY FLEXIBILITY AND REDUCED ENVIRONMENTAL IMPACT USING COMPACT SOURCES
Authors A. Long, M. Bastard, E. Asgedom, J.F. Wisløff, M. Widmaier and M. FaroukiSummaryWe examine compact air gun source concepts as a practical solution to mitigate the environmental impact of received sound levels during marine seismic surveys. The relative sound pressure level (SPL) and sound exposure level (SEL) are quantified for 1. Large arrays of air guns activated simultaneously with no significant recorded overlap in emitted acoustic pressure, 2. Small arrays of air guns activated simultaneously or in rapid succession, with recorded overlap in emitted acoustic pressure, 3. Individual air guns activated continuously with significant recorded overlap in emitted acoustic pressure—otherwise known as continuous wavefield acquisition, and 4. Marine vibrators that may sweep continuously and interfere with each other.
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RECORD OF SEA-LEVEL CHANGES ON A STRUCTURALLY ACTIVE MARGIN, OFFSHORE BRUNEI, NW BORNEO: IMPLICATIONS FOR RESERVOIR AND SEAL DISTRIBUTION AND STRATIGRAPHIC TRAP FORMATION
By E. KosaSummaryThe NW Borneo margin, offshore Brunei Darussalam, is characterised by high subsidence-rates (overall 1 km/MA over the last 14 MA; up to 6 km/MA locally) combined with large-scale, and rapid, syndepositional deformation driven by delta-loading and regional tectonics. Deformation includes extensional (regional and counter-regional), contractional, and strike-slip structures. Effects of eustatically driven variations in the Cainozoic sea levels, which are readily recognised in the stratigraphic records of many passive margins, including the neighbouring Sarawak-basin segment of the NW Borneo margin, have been subdued, or overwritten, by the subsidence signal on the Brunei margin. High rates of background subsidence have imposed limits on the duration of SL lowstands, while inversely amplifying the effects of eustacy-driven SL rises. This study is chiefly concerned with periods of eustatic SL lowstands, and with the imprint of subsidence-variations in space and time on the eustatic SL signal.
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MANAGING WELL PLACEMENT UNCERTAINTIES IN EXTENDED REACH HORIZONTAL WELLS USING DEEP RESISTIVITY INVERSION
Authors J.C.J. Yii, G.I. Santoso and K.A. AlangSummaryTwo Extended Reach Drilling (ERD) Horizontal wells were drilled in SK10 Sarawak Malaysia. The main objective was to penetrated B reservoir, that required minimum of 500m reservoir exposure in clean gas zone. Due to Geomechanic concern, those wells were designed with two different mud systems (SOBM in 12 _ inch hole landing section and WBM in 8 _ inch hole horizontal section). Seismic study revealed the reservoir vertical depth uncertainty remain as high as ±25m TVD, which posed significant challenges, in landing the 12 _ inch hole section conventionally. This paper will present the success story of planning, execution and advanced delivery product to land the well at 7m MD penetration into top reservoir and continue to place the well accurately at 2–3m TVD along the 500m MD horizontal section.
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APPLICATION OF 4D WHEELER DIAGRAM FOR CONSISTENT STRATIGRAPHIC HORIZON FRAMEWORK IN DEEP WATER SABAH
Authors H. Mohamed, M. Mohamed, A. Che Hassan, H.I. Darmawan, A. Ngau and N.Z.H. RedzualSummaryTypically, 2D horizons across calibrated well biostratigraphy data were done on regional lines to build consistent stratigraphic horizon framework. However, in Deep Water Sabah, the interplay of eustatic sea level change and tectonics are more complex. Each catastrophic events triggered old sediments transported further into basin and redeposited within younger sediment. This causing uncertainties to place ‘Last Appearance Datum (LAD)’ from biostratigraphic well data. At regional scales, calibration wells used are from different contractors where biostratigraphic data usually analysed and picked by different labs and contractors. These might lead to inconsistencies in some species identification especially microfossils preservation in a poorly recovered sequence. Thus made consistent stratigraphic horizon framework calibrated to well data in deep water is more challenging. In order to produce a consistent stratigraphie horizon framework in the Deep Water Sabah at basin and play scales, application of four dimension wheeler diagram (X,Y, Relative Geological Time and Thinning Attribute) was introduced.
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DEEP WATER HYBRID TURBIDITE CONTOURITE SYSTEMS HYDROCARBON POTENTIAL
Authors K. Rodriguez and N. HodgsonSummaryThe interaction of drift (or coast parallel bottom currents) and turbidite (or gravity) processes has only been recently recognized. The resulting mixed/hybrid turbiditic-contouritic systems are therefore just beginning to be understood. These are deep water depositional systems located in relatively frontier basins where modern 2D seismic is proving to be an essential tool in their identification and hydrocarbon potential evaluation, which must include a full petroleum systems review. This study focuses on recognizing and evaluating these mixed systems on seismic data using several examples from a comprehensive global long offset 2D seismic dataset. The huge potential already proven offshore Mozambique and Sergipe indicates that this depositional system should be a main target in deep water exploration. The Argentina Basin has strong indications of a significant accumulation offering a very attractive opportunity in the ongoing licence round.
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THE APPLICATION AND THE IMPACT OF NEW STANDARDIZED AND REFINED SEQUENCE STRATIGRAPHY CORRELATION IN WEST BARAM DELTA: CASE STUDY OF X FIELD
Authors N. Ramly, R. Bhatnagar, T. Sengwah, M.F. Sedaralit and N. MohsinSummaryThe understanding of sequence stratigraphy study is used as a chronostratigraphic framework for the correlation and mapping of sedimentary facies and for stratigraphic prediction (Emery et. al., 2005). The idea of a new approach of refined sequence stratigraphy for West Baram Delta (WBD) came considering of current reservoir correlations within the fields in WBD are done mainly based on lithology correlation. In addition, the unstandardized zonation throughout the fields in WBD contributes to discrepancy in static and dynamic modeling. The new standardized stratigraphic framework is built by integrating 3D seismic megamerged volume, well logs, and biostratigraphic data. In order to get the full impact and to add value to the new invention, a detailed study in field scale need to be done. Therefore, this study will focus on X field where the application of the new standardized and refined sequence stratigraphy is discussed. Technically, the refined stratigraphy and new reservoir scheme are utilized for better reservoir delineation and prediction in order to explore and develop the remaining upside potential within each stratigraphie unit, and to capture the bypass oil. The study has indicated a presence of an upside potential where it will be discussed in detailed in this paper.
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MATURATION OF A NEW PLAY CONCEPT IN THE PRE OLIGOCENE STRATIGRAPHY TO REJUVENATE EXPLORATION IN PENINSULAR MALAYSIA BASIN
Authors M.H. Damanhuri, A.A. Azman, S.I. R Iyer and F. IliasSummaryMalay and Penyu Basins are located on the eastern offshore area of Peninsular Malaysia. Hydrocarbon exploration in these basins have been focused mainly on the stratigraphic Groups M to B ranging in age from Oligo-Miocene to Pliocene. The exploration maturity for these plays is variable and the remaining portfolio consists of subtle structural/combination, and stratigraphic prospects and leads of small to medium size. Concerted efforts to rejuvenate exploration in this basin resulted in the identification of a new play of Pre Oligocene age (Early Tertiary or Mesozoic) spread over the southwestern Malay Basin, the northern flank of Tenggol Arch, and NE Penyu Basin. The new play with its explicit sedimentary character is present in two N-S trending grabens on the northern flank of Tenggol Arch. Several sizeable hydrocarbon prospects have been matured to test this play. A similar seismic package character even though not obvious in other parts of this basin is not evidence enough to rule out the presence of this play altogether. The present paper discusses the new play concept, predicted depositional model, and the petroleum system with supporting evidence. Significant exploration opportunities along the western flank of Malay Basin can be unlocked by proving this play.
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STOCHASTIC INVERSION OF D FIELD: INTEGRATION OF SEISMIC DATA AND GEOSTATISTICS TO EVALUATE CHANNELIZED RESERVOIR DISTRIBUTION
Authors I. Abdullah, A. Amdan, A. Khalil, M.A. Abd Mutalib and S. RajputSummaryThe study was conducted in the D field with complex compressional-extensional events causing the main field structure to have numerous compartmentalized fault blocks. In general, the relatively thin reservoirs, complex faulting and contacts are the principal challenges faced in this field. The reservoir distributions and connectivity de-risking by application of a stochastic simultaneous inversion workflow. The results then integrated and used as data input for reservoir static model. The challenges of this study are the thin beds, which justify the usage of the geostatistical inversion. The statistical component of the seismic inversion will model the results beyond the seismic resolution. At the seismic resolution, the convolution of the impedances with the wavelets will produce synthetics. The match between the seismic and synthetics must be good at the seismic resolution. Application of geostatistical inversion methodology in the D Field demonstrates that important improvements still can be made in reservoir characterization when the reservoir is below the seismic resolution. In addition, a better match of well data to inverted-results was achieved through geostatistical inversion than through deterministic inversion.
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ACQUISITION AND DE-BLENDING OF APPARITION STREAMER DATA
Authors S. Grion and L. CasasantaSummaryThis paper presents the acquisition and processing of a field test of triple-source streamer apparition, a blending technique for marine airgun sources that uses periodic codes in contrast with the more commonly used natural or artificial random dithers. The paper discusses the processing steps taken and the issues encountered while processing apparition data. We also compare migrated results to similarly processed data from a conventionally acquired triple source line. Conclusions are drawn on the benefits and opportunities of towed-streamer apparition for multi-source marine surveys.
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OPTIMIZATION OF IWAG INJECTION USING SEISMIC AMPLITUDE HOMOGENEITY - CASE STUDY
Authors S. Taha, N.L. Rafiuddin, S. Elkurdy, A. Roy and A. KhalilSummaryIn this study, we used seismic stratigraphy mapping to optimize EOR wells through testing reservoir sand continuity and communication between injectors and producers. Grey Level Co-occurrence Matrix (GLCM) tool is used in the study to facilitate mapping of top and base of targeted sand in order to generate thickness maps, also the GLCM assisted in enhancing the homogeneous seismic amplitudes at the reservoir level which facilitated the mapping of reservoir sand. The final stratigraphic interpretation proposes a new geological model of sand distribution suggesting fluvial dominated delta. The new model is supported by the water cut rates at individual wells indicating that it is related to the sand quality. The study provided solid understanding of sand distribution at injection level, and this understanding is used to further optimize the injector wells locations and securing the project’s objectives
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CASE STUDY: VALUE OF SIMULTANEOUS INVERSION IN A HEAVILY FAULTED MATURE FIELD OF LOWER COASTAL PLAIN SETTING, OFFSHORE SARAWAK
Authors A.L. Yahya, C.K. Tan, B. Bakhtiar, A.K.L. Ng, A. Rahmat, S.S. El-Kurdy, R. Doshi, N. Vargas and O. ColnardSummaryThe abstract highlight the role of simultaneous inversion in overcoming challenges for reservoir characterization of minor reservoirs - isolated channel sands with coals in a heavily faulted setting. The challenges are in determining the lateral distribution of these minor reservoirs, reservoir correlation involving isolated channel sands and coal, and reservoir mapping into undrilled fault blocks with complex structuring.
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SHALLOW HAZARD ASSESSMENT USING SEISMIC DATA – A SUCCESS CASE FOR SAFE DRILLING IN CENTRAL LUCONIA
More LessSummaryOffshore drilling operation in the oil and gas industry is complicated and exhibits different types of technical challenges as the mysteries of the water bottom conditions and the environments that occur at different depths. The recent drilling operations continue to encounter shallow geological hazards (geohazards) with different intensity. Many operating companies in the industry are running geohazard assessment surveys early on in the project to measure the degree of geological complexity and level of hazards associated with the drilling operation in the site. This paper is part of a geohazards study for an exploration well in the South China Sea offshore Sarawak, Malaysia. The assessment is based on integrating the interpretation of a high-resolution two-dimensional seismic data (2D) with the normal three-dimensional seismic data (3-D) to evaluate the near subsurface geology and identify the hazardous locations prior to the drilling campaign. Different seismic attributes maps such as Root Mean Square (RMS) and Variance generated to highlight features of interest and identify the hazardous areas. The results of the shallow hazard assessment were identifications of shallow gas accumulations at different levels, faults and channels in the area of interest
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BROADBAND MULTI-SURVEY FWI IMPACTS ACCELERATED CARBONATE DRILLING CAMPAIGN
More LessSummaryX field is a shallow water carbonate gas field in offshore Sarawak which came on stream in 2015. It is a large sweet gas resource, however, with low recovery factor due to the complexity of the field including highly karstified reservoir with short gas column, ‘pancake’ structure and a strong aquifer drive. The field complexity was further evidenced by early water breakthrough, several months earlier than the Field Development Plan forecast. Following the water breakthrough, decision was made in 2017 to accelerate Phase 2 infill development to safeguard the field production. Broadband Multi-survey FWI was one of the technology identified to help in placing the wells. This paper will show the improved image of the new data impacts the drilling campaign.
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3D STRATIGRAPHIC FORWARD MODELING IN FRONTIER AREA OF DEEP WATER SABAH
Authors N.L. Zainal, W. Ben Habel and S. JirimSummaryThis paper summarizes the study that have been conducted on simulating carbonate growth and spatial distribution through time in frontier environment using new technology stratigraphic forward modeling (SFM). The area of study is located in dangerous ground deep water Sabah. It offers a unique challenge for exploration as only two wells have been drilled in this area. Very few geological studies have been conducted in this area and results of the recent drilled wells have added more to the geological ambiguitiy of the study area. For this purpose, an innovative technique has been used to improve the geological understanding and better predict reservoir distribution for future prospects and plays SFM is deterministic and mathematical process tool. It is used to model the physic of sedimentary transport and deposition of silicicalastic and carbonate. It enables the geologist to test and validate the factors controlling depositional process by comparing the simulation results with soft data. In carbonate reservoirs, SFM is designed to predict reef growth with the goal of better understanding reef evolution and carbonate facies distribution through time and space.
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SUB-SURFACE INVESTIGATION IN THE FRONTIER REGION OF DEEP-WATER NW SABAH, MALAYSIA
Authors A. Banerjee, D.P. Ghosh, A.M.A. Salim and A.A. ZakariaSummaryWorldwide, deep-water exploration has increased significantly during the past decade. However, deep-water is not explored to its full potential and many new discoveries are expected to come in future particularly in SE Asia and East Africa. The petroleum systems of deep-water settings are highly variable in different basins globally. Successful exploration efforts in new basin will depend on improved understanding of the petroleum systems of the explored basins and advanced seismic techniques. Due to high resolution and high-quality recent 3D data in the frontier region of deep-water NW Sabah, we can extract and intricate geological features that are fascinating. Stratigraphic features like mass transport deposits, turbidites, isolated carbonate reef, channel cuts and depositional units namely syn-rift-I, syn-rift-II, Miocene-I, Miocene-II, Mid Miocene Unconformity, pelagic sediments and top of sea bed have been evaluated. Syn-rift-I sequence (presumably Late Oligocene time) consist of half-graben structures, syn-rift-II unit is overlying the thick syn-sedimentary clastics. Prominent channel cuts are observed on top of syn-rift-II unit. During middle Miocene time, the area experienced carbonate reef buildups on top of pre-existing paleo-highs. Reef build-ups are prominent below the Mid Miocene Unconformity. After the unconformity, the area received thick pelagic sediments.
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NEW IDEAS TO UNLOCK SRI LANKA FRONTIER OFFSHORE BASINS
Authors C. Tu and M. FrancisSummaryWith few data sets and little exploration activity, frontier basins are high risk, and yet have high potential return. The offshore Sri Lanka is such a frontier basin. To date, oil companies have only drilled fifteen wells (four of the fifteen were stratigraphic tests) offshore Sri Lanka. Five wells are in the West Mannar Basin. In 2011, two wells discovered gas: Barracuda and Dorado (Sorkhabi 2013). The remaining deep-water offshore basins, south and east of Sri Lanka, remain unexplored.
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PREDICTING STRATIGRAPHIC COMPARTMENTALISATION IN NEAR-SHORE LACUSTRINE SEQUENCES
Authors D. Shields and N. ZinSummaryDefining the lateral equivalence of reservoir units is a critical precursor to understanding reservoir communication and hence predicting fluid migration over a field’s production lifespan. To improve our understanding of reservoir architecture, sequence stratigraphic models were integrated with dynamic datasets applied to guide predictions of sand continuity and hence stratigraphic compartmentalisation which was previously not imaged.
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UNLOCKING KLIAS EXPLORATION OPPORTUNITY
More LessSummaryPETRONAS embarked on aggressive studies. The result of the study is relatively remarkable for the purpose to unlock the prospectivity of the frontier onshore Klias Peninsula. The new seismic data, geochemical analyses, FTG, structural restoration and basin modeling have provided a better understanding of the geology of the Klias Peninsula that could fascinate exploration activities to explore the hydrocarbon potentiality. MPM as the opener and shaper of the exploration activities for the frontier areas believed that there is value creation for the exploration from onshore Klias Peninsula and the surrounding area in future.
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AN INTEGRATED APPROACH OF 3D STRATIGRAPHIC FORWARD MODELLING AND SEQUENCE STRATIGRAPHY TO PREDICT RESERVOIR HETEROGENEITY IN SUBMARINE FAN OF DEEPWATER SABAH
Authors M.R. M Radzi, W. Ben Habel, S. Jirim and S.N.A. Syed KhastudinSummarySubmarine fan and related deep marine deposits consist of estimated 15% of the world proven total oil reserves in clastic dominated hydrocarbon systems ( Richards et al, 1998 ). Northwest (NW) Borneo is one of the prolific oil and gas province attributed from deep marine deposits with Kamunsu, Kinarut and Kebabangan are the proven main reservoir intervals. Despite of their high hydrocarbon potential interval, complexity of predicting reservoir distribution and continuity remain as a challenge in this area. These uncertainties could be reduced by integrating result of sequence stratigraphic study and 3D stratigraphic forward modelling (SFM). Stratigraphie forward modelling (SFM) demonstrates its applicability in exploration by providing a highly predictive stratigraphic framework. By integrating 3D SFM and sequence stratigraphy analysis, it will be able to provide guidance on subsurface lithofacies distribution in the area that can be used to derisk reservoir presence to support the drilling of identified prospect in deepwater Sabah.
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DIGITAL ANALOG INTELLIGENCE HELPS MITIGATE E&P RISK
Authors S. Sun, J. Faroppa, S. Wu and B. ZhengSummaryBased on the structured and regularized data, DAKS provides insight, intelligence and solutions to support E&P decision-making through its global field and reservoir knowledge base, pioneering classification scheme and powerful set of analytics tools. With the analytics and intelligence, geoscientists, reservoir engineers and portfolio managers will be able to quickly and efficiently expand their own experiences and be more creative to minimize the risks and achieve superior performance. The author will present case studies to demonstrate how DAKS digital intelligence has been applied in identifying prospect critical risks, calibrating subsurface uncertainties ( Figure 2 ), validating reservoir models and development concepts, and mitigating E&P risks with examples from the Gulf of Mexico, South Atlantic Margin Basins, and the North Sea.
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SURVEY DESIGN IN ANISOTROPY MEDIA FROM FOCAL BEAM ANALYSIS
Authors A.H. Abdul Latiff, Z. Mohd Zaki and W.I. Wan YusoffSummaryThe insufficient sampling parameters will result in an acquisition footprint on time slice, low resolution, unreliable angle-dependent reflection amplitude (AVP-information), low signal to noise ratio and incorrect velocity estimation. One way to design a reliable seismic survey is through the focal beam method, where it has the advantage of analysing resolution and AVP imprint caused by incomplete acquisition design. In addition, the focal beam analysis able to determine the seismic contribution from either the receiver or the source side only. While the focal beam method is extensively used in homogeneous and heterogenous media, the application in inhomogeneous medium and extending them to anisotropy medium can increase the focal beam analysis value.
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PREDICTING PORE PRESSURE WITHIN BARAM DELTA OVERPRESSURED ZONE
Authors W.A. Wan Mohd Kamil and F. WijnandsSummaryUndercompaction plays an important role but secondary mechanisms appear to be active. Based on acquired data and geological knowledge, we speculate that vertical/lateral transfer of pressure, controlled by impermeable shale (some as thin as 10 m) and small faults (possibly occasionally reactivated) control the present day deep pressure regime in the Baram Delta.
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HIGH SLANTED DEVELOPMENT WELLS TURNED RISKY PROSPECT TO RESERVES IN BONGKOT MATURE GAS FIELD, GULF OF THAILAND
By N. SukkeeSummaryMore than two decades of Bongkot field production, conventional resources/reserves have been produced. Lowest investment was considered to the infill development program with challenging well designs. In 2018, drilling operation of high slanted development wells was completed successfully. This project illustrated the efforts of the operator to propose innovative solutions to save cost and ensure sustainable additional development for a mature Bongkot field.
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EARTH MODEL BUILDING FOR THE DEEP-WATER FRONTIER EXPLORATION AREAS OFFSHORE SABAH, MALAYSIA
Authors R. Chakraborty, G. Menzel-Jones, A. Sazykin, N. Adelman, M. Tham, D. Barlass and R. DixitSummaryRecent interest in the Malaysian deep-water acreage created a requirement to build reliable regional interpretation over large prospective areas and led to a broadband multimeasurement towed-streamer acquisition of over 19,500 km2 offshore Sabah. In this work, we discuss the overall earth model building strategy that enabled creating a high-quality, high-resolution, contiguous earth model and broadband images over a large area of considerable geologic complexity and variation. We emphasize the importance of interpretation-guided anisotropic earth model building to enhance prospect evaluation in this underexplored and frontier exploration province, proximal to successful exploration trends within the Sabah thrusts zone and Luconia carbonate shelf.
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OLIGOCENE AND MIOCENE SEQUENCE STRATIGRAPHY OF THE NORTH MALAY BASIN, MALAYSIA AND THAILAND
Authors G. Brink, J. Hernandez, J. Bencomo, L. Jiang, N. Koronful, D. Basu, A.Z. Ishak, M.F. Ali and J. SkulsanjutrSummaryExploration activities in the Malaysia Thailand Joint Development area have been conducted since 1971 and nine gas fields are currently producing at relatively shallow stratigraphic levels of late Miocene age. The sequence stratigraphic study area covers 7250 Km2, which includes an area covered by some 300 wells, 6400 km2 3D surveys and 10664-line Km of 2D seismic. We have established a seismic and sequence stratigraphie framework, validating depositional systems through time and synthesizing various chronostratigraphic schemes published to date.
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APPLICATION OF ITERATIVE LEAST SQUARES MIGRATION IN DIFFERENT GEOLOGICAL SETTINGS
Authors Ø. Korsmo, S. Arasanipalai, Z. Greplowski and M. FaroukiSummaryLeast-squares migration has over the last few years become the new standard in high-end seismic imaging. In this paper we utilize iterative least-squares migration in different geological settings from shallow complex structures to deeper sub-chalk and sub-salt targets. We evaluate how least-squares migration can improve the wavenumber content, suppress illumination effects from acquisition design and velocity anomalies and reveal finer structural detail compared to conventional migration. By utilizing the one-way extrapolators, the inversions can be done for the full frequency range supported by the data at an acceptable cost.
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IMAGING THROUGH COMPLEX SHALLOW GAS WITH FULL-WAVEFORM INVERSION TO ENHANCE THE DATA INTERPRETABILITY OF THE DEEPER TARGETS IN THE TARANAKI BASIN, NEW ZEALAND
More LessSummaryThe Western Platform 3D survey is in the Taranaki Basin, offshore New Zealand. The survey was designed and positioned to provide a high-resolution 3D broadband data set on trend to and over multiple oil and gas fields to provide new insights into and allow better analysis of proven and unproven plays. The client’s needs in the region to identify residual hydrocarbons beneath shallow gas clouds within complex stratigraphic intervals led to Schlumberger providing a detailed bespoke workflow to address the imaging issues encountered in legacy datasets. The legacy imaging efforts have suffered due to being unable to overcome the presence of multiple geological challenges. To address these challenges, full-waveform and common image point tomography were performed to derive a high-resolution velocity model. Q-FWI was used to derive a detailed Q model representing the shallow gas bodies. In this case study, we demonstrate the successful application of diving-wave FWI, Q-FWI, and FWI using reflection energy to resolve a high-resolution velocity and Q model. This detailed model enabled the final imaging performed with Q-Kirchhoff prestack depth migration to compensate for the complex kinematics and gas-related absorption effects observed in the survey.
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PERMANENT DOWNHOLE SEISMIC MONITORING FOR CO2 GEOSEQUESTRATION: STAGE 3 OF THE CO2CRC OTWAY PROJECT
Authors R. Pevzner, S. Glubokovskikh, K. Tertyshnikov, S. Yavuz, A. Egorov, E. Sidenko, S. Popik, L. Ricard, J. Correa, T. Wood, B. Freifeld and B. GurevichSummaryTime lapse (TL) seismic plays a key role in monitoring of changes in the subsurface caused by reservoir production or CO2 geosequestration. However, applicability of the TL seismic is limited by several factors, which include: relatively high cost; relatively high degree of invasiveness and associated land access issues; sparseness in time and usually significant delay between the acquisition and availability of the interpretable data. Stage 3 of the CO2CRC Otway project is aiming to address these issues through deployment of a permanent seismic monitoring system built on a combination of permanent orbital vibrators and multiple closely spaced wells instrumented with fibre optic cables for distributed acoustic sensing. Here we discuss the seismic monitoring program for Stage 3 and illustrate it with the results of a number of trials conducted on site while developing the program.
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MAXIMIZING SECONDARY OIL RECOVERY AND IMPROVING RETURNS BY OPTIMUM WELL PLACEMENT IN MATURE FIELDS
Authors S. Rajput, A. Khalil, N. Bt Mat Khair, Y. Sam, A. Roy and A. B. KhalidSummaryThis paper answers two important mature field re-development questions on secondary oil recovery. 1. How to maximize oil recovery? and 2. How to improve returns from mature assets? In this study, multi-disciplinary subsurface information was integrated to design four water injectors and five oil producers in a producing oil field for maximizing secondary oil recovery. A geostatistical inversion based algorithm was utilized to derive the lateral and vertical reservoir distribution and sets of equiprobable values of simulated rock properties generated. Joint geostatistical seismic Inversion (JGSI) driven Acoustic and Shear impedance (AI-SI) together with probability density functions from well logs were used to generate probability linking volumes for each reservoir. The key features that affect reservoir connectivity were identified by geostatistical inversion driven probability linking mechanism with reasonable accuracies, but with varying interpretations of fluid movement in the reservoir. Reservoir architecture was better understood with the integration of available geological information, well log interpretation and quantitative seismic derivatives. Waterflood impacted positively and the production has been increased from 25 – 40%. This added significant value to the project and the water injectors are self-sufficient in terms of cost recovery. Increased oil production improved the retunes on the asset.
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VALUE OF CORE TO SEISMIC SCALE DATA EARLY IN THE APPRAISAL PHASE, OFFSHORE SARAWAK
By J. AnthoaSummaryIn mid-2018, ConocoPhillips and its joint venture partner, PETRONAS Carigali drilled 2 E&A wells, Salam-2 and Patawali-1 well in Block WL4-00, Offshore Sarawak. The wells discovered oil and gas in multiple sands within the Late Miocene Cycle V interval.
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RESERVOIR CONNECTIVITY ANALYSIS BY INTEGRATING PROBABILISTIC DISTRIBUTION OF FLUIDS AND FACIES WITH STOCHASTIC INVERSION
Authors S. Rajput, M.A. B Abd Mutalib, R. Pathak, R. Adawiyah Bt M Ghozali, A. B Khalid, N. Nathesan and Y. SamSummaryOil, gas and water fluid in structurally complex channelized or faulted reservoirs can create complex reservoir plumbing relationships and reservoir connectivity can be mis understood, specially in water flood envireonment. Variable hydrocarbon contacts can develop when some, but not all, fluids are in pressure communication. Seismic based reservoir connectivity analysis is a series of steps to integrate structural complexity, stratigraphic units, and fluid pressure and composition data into permissible but non-unique scenarios of fluid contacts and pressures leveraged by seismic inversion derivatives. This new analytical approach has been used in a wide range of reservoirs including clastic and carbonates in the field around the world. The paper detailes an innovative workflow for reservoir connectivity analysis and highlights effective integration of probabilistic distribution of fluids and facies with stochastic inversion derivatives and static model. The results from infill drilling program were analyzed by integrating the geological models, 3D seismic, petrophysics, and reservoir engineering data to better understand the reservoir continuity. The study reveal that effective integration of this information with post drill data provide a more reliable and quantitative prediction of reservoir continuity and helps in designing the future drilling programs and optimizing water flood projects for improved oil recovery.
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ENHANCING DEEPWATER HYDROCARBON SEEPS HUNTING BY INTEGRATION OF SEISMIC, MULTIBEAM ECHO SOUNDING, AND GEOCHEMISTRY SURVEYS
Authors M. Mustaza, S.K. Tham, K. Norhasliza, K. Ruszaidi and R. M HelmiSummaryDeepwater hydrocarbon seeps hunting by multibeam echo sounding (MBES), high-resolution sub-bottom profiling, and geochemistry surveys de-risk tools for wildcat and new frontier explorations. The later are usually based upon seismic geophysical survey interpretation from which potential hydrocarbon prospects are mapped.
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SHALLOW-WATER OFFSHORE SABAH MALAYSIA REPROCESSING WITH HIGH-END IMAGING LEADING TO SIGNIFICANT IMAGING UPLIFT AND ENHANCED RESERVOIR UNDERSTANDING
Authors C. Wai Ling, G.M. Jones, N.A. Mohamad Radzi, M.A. Ismail, L.W. Long, S.F. Zohdi, K.K. Pillai, A. Sazykin, A. Waluyo, A. Muhamad, M. Ghazali and N. IsaSummaryReprocessing and reimaging legacy surveys can add significant value to existing seismic data sets while eliminating the requirement to acquire new data. During reprocessing work, an appropriate strategy must be set early on with the required technologies included in the processing flow to ensure that the desired uplift over the legacy seismic images is achieved. We present a case study of reprocessing and reimaging a legacy data set with the clear objective of enhancing the reservoir understanding. The broadband processed data, coupled with a tailored model building and depth imaging workflow, led to delivery of a clearer, more interpretable image, relative to the legacy processing. This image provided significant assistance and insight to the asset and interpretations teams in their evaluation of the field geology and reservoirs.
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UNLOCKING THIN OIL RIM RESERVOIRS IN EOR FIELD OFFSHORE MALAYSIA WITH INTEGRATED GEOSTEERING METHODS
SummaryThis paper will discuss the integrated process flow from planning until the execution of horizontal well in offshore Malaysia. The main challenge includes the present of extremely thin oil rim and the possibility of tilted fluid contacts. Discussion will cover the successful application of geosteering integrated with real-time data such as reservoir mapping tool, LWD and gas analysis data to ensure optimum horizontal well placement despite these challenges and has made the high-risk well successful and completed.
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A QUALITATIVE APPROACH FOR THIN BED RESERVOIR INTERPRETATION, A CASE STUDY IN AN ULTRA DEEPWATER FIELD, SABAH
More LessSummaryThe ultra-deep water Jewel field is situated in the southern corner of Block K, approximately 150 km Northwest of Labuan and in water depth of 1662m. Based on exploration and appraisal drilling, the field is observed to be highly compartmentalized with reservoirs being thin. In this ultra deep water setting, there is a heavy reliance on seismic data to help delineate the reservoir. The field Seismic data however has limitations where due to its low signal to noise ratio and the vertical resolution is deemed to be poor. As such, the thin beds prominent in Jewel field may not be fully resolved causing the thin hydrocarbon bearing reservoirs to go undetected. The presence of shallow gas accumulation can be a good indicator of a working petroleum system but these shallow gas in Jewel field masks the underlying seismic reservoir response as well as push down events causing time delay of the field structure.
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TARGETED VS. REGIONAL MODEL BUILDING AND IMAGING - A CASE STUDY FROM OFFSHORE SABAH, MALAYSIA
Authors D. Cavalin, Y.M. Wong, A. Bromley, M. Farouki and K. AgbebiSummaryMulti-Client (MC) surveys are typically large, regional in scope, and are intended to serve primarily for exploration purposes. Accordingly the velocity model building and imaging approach employed is designed to accommodate the regional geology across the entire survey area, and may therefore need to be customized to meet the requirements of specific exploration plays. For example, more detailed velocity analysis such as Full Waveform Inversion (FWI) together with imaging algorithms that can make use of the detail that is introduced in the velocity model, may be required for improved structural imaging of a particular prospect. In this regard it is important that the quality of the recorded seismic data and pre-processing flow supports the application of a targeted workflow which includes advanced modelling and imaging techniques. This case study compares the results of regional and targeted imaging approaches on a MC survey acquired in Block ND5, offshore Sabah, Malaysia.
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SEAMLESS INTEGRATION OF ACQUISITION, PROCESSING AND INTERPRETATION OF MULTI AZIMUTH STREAMER 4D ENABLING TIMELY IMPACT ON THE NEXT DEVELOPMENT PHASE OF A MALAYSIAN FIELD
Authors I. Rahman, G. Balakrishnan, L. Chee Kiong and A. TanSummaryThe key success indicator for time-lapse seismic begins at the acquisition stage in the aspect of positional repeatability of seismic sources and receivers. To achieve this, the first step in the survey planning is to understand the Base survey design, source-receiver positioning, feathering angle and ocean current direction and magnitude.
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DETECTING SILLS AS KINEMATIC INDICATORS BASED ON SPECTRAL DECOMPOSITION – INFERRING STRESS REGIME IN THE MALAY BASIN (FRACTURED BASEMENT RESERVOIR)
Authors A.A.S. Shamsuddin, S. Shahar and D.P. GhoshSummarySeismic imaging issues and approaches which are related to resolution hinder the understanding of the fractured basement in terms of geological complexities of rock types and tectonic regime. They were implemented in detecting mesoscopic scale fracture. In principle, fracture scale varies and its combination is defined as fracture network. A study was conducted by integrating surface and subsurface in order to enhance the understanding of the fractured basement. In this study, we provide the kinematic indicators as structural evidences in inferring and enhancing the understanding of stress regime. Outcrop analysis provides new insight on the complexity of the fractured basement where kinematic indicators, dolerite dykes were observed in the Peninsular Malaysia (Eastern part). In the fractured basement of the Malay Basin, spectral decomposition was used to detect kinematic indicators, sills. The results presented in this paper are consistent with existing igneous rocks that were observed in the core and cutting. This study proposes horizontal shortening during sills emplacement in the N-S to NW-SE orientations, followed by sinistral motion in subsurface area and dyke in surface area suggests horizontal extension. Dyke-sill influence in the fracture basement area needs further study in order to evaluate source/reservoir potential of the fractured basement reservoir.
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PROSPECTIVITY OF MESOZOIC CARBONATE ALONG CENTRAL ATLANTIC NW AFRICAN MARGIN
Authors S.S. Aziz, N. Tukimin, S. Dasgupta, Y. Lai Kee and H.A. Mohamad IdrisSummaryThe regional geological setting of the North Atlantic region during the Middle Jurassic to Early Cretaceous is recorded as separation between the West Gondwana and Laurasia continents. This evolution subsequently developed the North Atlantic between Eastern North America and North West Africa. Carbonates of Jurassic and Lower Cretaceous (Barremian and Aptian) ages in these conjugate margins are identified as possible exploration targets along the paleo-shelf region. Reservoir quality due to diagenesis has been observed to be one of the key risks for these carbonates. Better reservoir quality due to karstification is observed in sandy dolomites in onshore Morocco. Based on limited well information in offshore Senegal, the fractures in Barremian carbonates are filled by coarse crystalline calcite. Few Aptian carbonates in offshore Senegal shows extensive fractures over major local uplift. Vugs and open fractures are abundant within the carbonates with prominent oil show. Possible carbonate progrades of Aptian age in Guinea Bissau may also have reservoir potential. Despite few successes in Mesozoic carbonates, further exploration needs to be conducted for commercial discoveries.
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MODERN SEISMIC DATA REVEALS POTENTIAL FOR A DEEPER PLAY IN NORTH MADURA, EAST JAVA, INDONESIA
Authors M. Farouki, A. Bromley and D. CavalinSummaryThe East Java Basin is a prolific hydrocarbon province in Indonesia in which exploration plays have typically targeted the pinnacle reefs of the Oligocene-Miocene Kujung carbonates. Robust imaging of the deeper section however has historically been challenged due in part to the limited bandwidth of conventional seismic data. A further challenge arises from the imaging artefacts introduced at the overlying Wonocolo carbonate platform, where the slow velocities of deep channel incisions are in strong contrast with the fast carbonate velocity. Pre-stack depth migration can be used to address this issue, but requires a velocity model with sufficiently high spatial and temporal resolution to precisely capture such velocity variations. To this aim, Full Waveform Inversion is used in the velocity model building. Whereas legacy data in the basin has struggled to image deeper than the Kujung level, seismic acquisition and imaging methods are now providing data with greater bandwidth and deeper penetration of signal. In Madura, the deeper Eocene Ngimbang formation as well as basement are now much better resolved, opening up the potential play in the Ngimbang clastics.
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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. Anwar, R. Roslan, R. Danial, 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. Drilling into basement can be a challenge, especially accurate identification of the top of fresh basement. Weathered basement rocks are geo-mechanically less stable compared to fresh basement rocks hence can cause operational problems. Often, drilling parameters and Logging While Drilling (LWD) logs can accurately determine the top of fresh basement, however, there are many wells where the difference between the weathered and fresh portion of the basement is more subtle. In this paper, we will describe one of the more recent success stories in characterizing the weathered and fresh portion of the basement while drilling. The well was located offshore Peninsular Malaysia and was designed to target the granitic basement below its clastic objectives. In addition to the conventional description by the well site geologists, the cutting samples are subjected to X-ray Diffraction (XRD) and X-ray fluorescence (XRF) in order to obtain the bulk mineralogy and elemental composition respectively. The well successfully penetrated 6 meters of fresh crystalline basement with 15 meters of weathered basement on the top.
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REASSESSMENT OF SAND FAIRWAY FOR DISTAL TOE THRUST PLAY IN DEEPWATER SABAH
Authors M.E. Ab Rahman, N.Z.H. Redzual, H. Mohamed, H.I. Darmawan, A. Ngau, F. Mohd Zaffa and K.A. M KamilSummaryDistal toe-thrust plays in Deepwater Sabah are considered very high risk plays in terms of the petroleum system despite the possible high returns for their larger structure size. Reducing the uncertainties of reservoir presence and effectiveness remains a challenge as the plays are located tens to hundreds of kilometers away from sediment sources. General observations through well data correlation concluded that decreasing reservoir NTG is observed as one moves from proximal to the further distal toe thrust areas. As such, the latter becomes a less attractive area of play. In 2018, a total of 44,100 km2 of multiples multi-client (MC) 3D seismic surveys were optimised for exploration activities that includes the Sabah fold/toe-thrust belt, Sabah Through and NW Sabah Platform. Structural maps of Stage-IVC equivalent over a 7000 km2 of 3D Seismic MC Phase-2 survey and seismic amplitude cross section show that the wells drilled to date are located at the structural crest. In contrast, seismic sweetness attributes section shows high amplitude presence at the distal toe thrust area, indicating potential sand presence away from existing wells. These observations became the main drive for the reassessment of sand fairway across this area, in the attempt to delineate possible untapped prospects.
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IDENTIFICATION OF A BACK BULGE BASIN IN THE NORTHWESTERN PART OF BARITO BASIN (BORNEO, INDONESIA)
Authors S.S.M. Singh, L.S. Binel, M.N. Juliansyah, F.H. Darmawan, M.L. Lee and X. LegrandSummaryA Foreland Basin System consists of four depozones, namely the wedge-top, fore deep, fore bulge and back-bulge. Barito Basin, a typical foreland basin system located in Southern Kalimantan, Indonesia is bounded between Sundaland to the North-West, the Meratus Range to the South-East, and the Adang Fault to the North. In this paper, the NW part of this system which is our area of interest is interpreted as a Back Bulge Basin with its own potential petroleum system.
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APPLICATION OF INTEGRATED AND ITERATIVE SEISMIC PETROPHYSICS AND ROCK PHYSICS MODELING: CASE STUDY OF “L” FIELD
Authors A. Ab Fatah, T.M.S. Tengku Hassan, R.P.A. Bekti and C.S. LeeSummaryThe integrated and iterative seismic petrophysics – rock physics is a powerful workflow to generate consistent petrophysical evaluation on the logs as well as producing reliable, predictive rock physics model that can generate consistent elastic logs for seismic characterization work. This workflow focuses on integrating different disciplines such as petrophysics, geophysics, and geology as an input to generate a set of consistent data interpretation that can be used as a predictive tool away from the well locations. The advantage of an iterative process used in this methodology between logs conditioning, seismic petrophysics and rock physics modeling is to ensure that the quality of the outputs is high hence assist in improving the interpretations of any future seismic reservoir characterization workflow to be applied the seismic data ultimately.
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RE-IMAGING BANDA ARC USING FULL-WAVEFORM INVERSION AND BROADBAND IMAGING
Authors K.P. Soo, J. M Zamri, K.K. Wong and B.Y. OngSummaryReprocessing of vintage 2D seismic was conducted to improve the imaging of the thrust complex and sub-thrust structures of Banda Arc. The objective was achieved by implementing advanced processing technologies, including high-frequency full-waveform inversion (HF-FWI) and broadband joint designature and deghosting. HF-FWI is a data-driven method designed to produce a high-resolution velocity model, which is crucial for PSDM imaging. It is a way of updating an initial model using velocity perturbations derived directly from the comparison of modeled seismic records to acquired seismic records. The updates started from 4Hz using the transmitted energy (head waves and diving waves) and extended up to 24Hz utilizing the reflection energy as well. The resulting HF-FWI velocity model displays high-resolution and good geological correlation. The pre-migration broadband joint designature and deghosting technology produced a more stable wavelet phase than conventional deghosting. A more accurate and focused image was achieved, especially in the low frequency range. These key technologies provided an overall uplift in image quality, better energy recovery and clearer structures at the deeper sections of the complex thrust. In addition, the uncertainty below the thrust complex was reduced, thus increasing the understanding of the hydrocarbon systems and risks involved in future explorations.
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BASEMENT CONTROLLED STRUCTURATION IN WEST AFRICAN SALT BASINS
Authors J. Shah, I. Ismail, G. Aird, K.H. Leong, S. Mustafa and F.P. FerrerSummaryBasement structures and their tectonics have important role in architecting the plays and traps in the Post-salt sediments. The important parameters which should be studied carefully to understand the structuration in the Post-salt sediments are (i) salt thickness, (ii) detachment slope (iii) amount of overburden and (iv) inherited topography for the basin on which salt was precipitated. The tectonic fabric of the basement is a major controlling factor in defining the structure size as well as sedimentary facies distribution in the sediment sequences deposited atop a relatively planar Salt Basin of Southern West Africa. The deformation and sediment distribution through time is controlled by the tectonic fabric of the basement in West African Passive continental margins. Thus, it’s implication on the formation of prospective hydrocarbon traps should be studied carefully in order to downsize the uncertainty and improving the chances of success.
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APPLICATION OF MACHINE LEARNING FOR POROSITY PREDICTION USING 3D SEISMIC DATA
By J. MalikSummaryPrediction of reservoir properties using different datasets is very crucial for planning field development and management.
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UNDERSTANDING CARBONATE PRESENCE IN CYCLE I OFFSHORE SARAWAK THROUGH FSM & OUTCROPS ANALOGUE
Authors J. Margotta, M.H.H. Mohammad, G.S. Primadani, M.S.F. Abdul Razak, A. Kumar and Z. ZahirSummaryThis study integrates regional sequence stratigraphy, forward stratigraphic modelling and analogues from onshore outcrops in Sarawak to highlight an innovative integrative approach of the stratigraphic architecture, depositional processes and possible hydrocarbon potential of Cycle I deposits in Central Luconia.
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RELATIONSHIP BETWEEN KARST DEVELOPMENT, COLLAPSE SINKHOLES, & FAULT TRENDS TO DEVELOP THE FIRST CENTRAL LUCONIA'S CARBONATE KARST ISLAND MODEL
Summaryhe paper focuses on the relationship among the karst collapse sinkholes, extensional fault trends, and associated offset talus debris observed on several Miocene carbonate platforms of Central Luconia, Sarawak. The Central Luconia province is divided into several tectonic highs i.e. Mega Platform, G Fields High, Bunga Pelaga High, and Southern Field High. The carbonate platforms studied for the analysis are carbonate platforms located on the Bunga Pelaga High. As of now, there have been no in-depth studies concentrating on establishing the first Central Luconia’s Carbonate Karst Island Model. Each of these carbonate platforms actually creates the ideal background platform to further analyse the aforesaid carbonate island karst model. Sea-level changes are a critical factor that influences the distribution and the density of the karst formation. The type of karst features formed on a carbonate platform is also influenced by the rise and fall of the sea-level because these changes of sea-level will influence the period of exposure which in turn, will determine the duration of Stillstands that is needed to create the karst features. Therefore, to further analyse these carbonate platforms, results of this analysis will help construct the carbonate karst island model for the Bunga Pelaga High carbonate platforms.
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THE OCCURRENCE OF CLASTIC SUCCESSIONS BELOW UC-3 UNCONFORMITY IN SOUTH MALAY BASIN: A NEW INSIGHT FROM PETROGRAPHY, XRD AND SEM ANALYSES
Authors A.H. Hashim, Z. Konjing, N. Pendkar, S. Iyer R Iyer and M.H. DamanhuriSummaryThis report presents the results of a multidisciplinary sedimentological studies for eight wells, located within South Malay Basin offshore Terengganu, Malaysia. The study intervals focus on the Pre-Tertiary - Early Tertiary aged successions below the UC-3 unconformity. A multidisciplinary study has been conducted on selected cutting samples from different wells, drilled from this region to analyze the reservoir potential and to confirm the occurrences of clastic successions below the UC-3 unconformity. To achieve this, a total of forty samples were selected from eight wells namely Well A, Well B, Well C, Well D, Well E, Well F, Well G and Well H.
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IMPROVING BASEMENT DEPTH MAPPING USING JOINT 3D INVERSION OF MT PHASE AND AMPLITUDE
Authors A. Karpiah, M. Meju, R. Miller and R. MusafarudinSummaryElectromagnetic methods are established tools alongside gravity and magnetics for non-seismic mapping of crystalline basement. Accurately mapping the boundary between sedimentary cover rocks and the crystalline basement has implications for hydrocarbon prospectivity of a basin. We apply 3D joint inversion of MT amplitude and phase data to image and resolve an observed discrepancy between basement depth interpreted from seismic and that from independent gravity and magnetic 2D modelling in offshore Borneo. We performed an unconstrained 3D inversion of the available marine MT datasets using CGG’s RLM3D inversion code. The 3D MT inversion result suggests a basement structure different from those previously interpreted using 2D structural restoration from seismic image and 2D potential field inversion. We suggest that 3D inversion is required for such complex terrains.
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AN INTEGRATED FORWARD STRATIGRAPHIC MODELING STUDY OF A FIELD IN CENTRAL LUCONIA WITH COMPLEX INTERNAL ARCHITECTURE, FACIES AND KARSTS
Authors M.H.H. Mohammad, D.A. Uli, Z.Z. Tuan Harith, A. Kumar, A. Kolupaev, S.F. Lim and Y.F. ZainudainSummaryThe paper discusses an innovative methodology of designing a carbonate reservoir model on a field in Central Luconia for planning further optimal field development and reservoir management & surveillance (RMS) using a Forward Stratigraphic Modelling (FSM) approach. The method used in the FSM approach is to first set the modelling input parameters which mostly represents the main depositional processes such as conditions of wave energy & direction, paleobathymetry, carbonate production rate, eustatic changes, amount of subsidence etc. These input parameters are obtained from an integrated approach of analysis on all hard data available including understanding of modern analogues to create a conceptual model at time of deposition. The steps are reiterative until an acceptable match between the model results and the hard data is obtained. Overall, the FSM model aided greatly in understanding the Internal Reservoir Architecture, Facies distribution and also Karst Interpretation in the field.
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KARST GEOBODY EXTRACTION THROUGH THE COMBINATION OF KARST CHARACTERISATION WORKFLOW AND PRINCIPAL COMPONENT ANALYSIS (PCA) IN CARBONATE FIELDS OF CENTRAL LUCONIA PROVINCE, SARAWAK
Authors S.F. Lim, D.A. Uli, A. Kumar, M.H.H. Mohammad, Z. Mohammad, Z.Z. Tuan Harith, A. Kolupaev and Y.F. ZainudainSummaryThe paper presents a method to quantify karst features present in the carbonate fields in Central Luconia Province, in terms of 3D geobody grids with distinct volumetric and reservoir properties. Several carbonate gas fields in Central Luconia province have experienced unpredicted high-water production and early water breakthrough during the production phase of the field. The assumption for the reasoning on the unpredicted water breakthrough issue for the fields was based on 2 reasons i.e. strong water aquifer from below the gas-water contact and high internal carbonate reservoir heterogeneity. A comprehensive analysis was designed for this issue, which includes 3 components: Forward Stratigraphic Modelling (FSM), karst network characterisation and mapping, and uncertainty management. This paper itself discusses the mapping and picking of the karst grids using Principal Component Analysis (PCA) which is a type of Train Estimation Model. Previous carbonate geological models have always modelled karst features as property trends, based on seismic attribute analyses or through delineation of karst polygons which then overestimated/underestimated the karst features. These practices are not as effective because karst features in carbonate fields have a profound effect on the reservoir’s flow units, for they will influence the internal geometry and architecture of the carbonate fields.
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SALAM-2: SUCCESSFUL APPRAISAL FROM THOUGHTFUL FRAMING
Authors M.F. Mohd Fuad and I. SunhajiSummaryAn appraisal well was drilled to delineate the oil and gas discovery at the Salam field, offshore Sarawak. Prior to the drilling campaign, a new 3D seismic survey was acquired over a total area of 1,631 square kilometres covering the Salam field and adjacent structural trends. The seismic survey was acquired using a proprietary seismic acquisition and processing technology known as Compressive Seismic Imaging (CSI). This paper discusses the thought processes that resulted in critical decisions made on the well location selection and data acquisition plan. The Salam-2 appraisal well successfully addressed the most important subsurface uncertainties which would influence EUR of a potential Salam field development. The high-quality 3D CSI seismic was a key enabler in improving depth, lithology and fluid phase prediction, and ensuring accurate well placement. More importantly, systematic problem framing and identification of key uncertainties up front resulted in successful appraisal drilling. This approach has minimized appraisal costs and facilitated a faster transition from Exploration to Development Phase.
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INTERPLAYING TURBIDITE DEPOSITS ASSOCIATED WITH MULTIPLE FEEDER SYSTEMS: A CASE STUDY FROM NW SABAH BASIN
Authors S. Nayak, P.S. Das, A. Ngau and A.H.B. MohdSummaryUnderstanding sediment dispersal and reservoir development in deep water have been critical for any the exploration campaign. Complexity in reservoir development has been related to depositional elements, processes and nature of sediment input. This paper discusses, multi-source “Interplaying turbidite systems” in deep water regime, where sediment inputs are from multiple feeder systems. One of the relevant analogue for understanding the concept of “Interplaying turbidite system is the greater Bengal fan, where the sedimentation is from various directions. Sediment fill in two major basins namely Mahanadi and Rakhine, on the western and eastern flank of Bengal fan respectively provides insight to intermixing of sediment related to multiple feeder systems Seismic geomorphic study and heavy mineral analysis indicate the presence of multi-source sediment delivery systems in the Sabah deepwater. At least three different systems contributing sediments into the Sabah deepwater have been identified. Sediment fed by each of these systems can show different properties depending upon the provenance, physiographic nature of source margin, distance from source provenance. Interplay of these systems result in varied reservoir development in time and space. Detailed seismic interpretation, sedimentology and heavy mineral analyses are proved to be useful in understanding source-to-sink correlation. Correlating turbidite fans to respective source provenance, is instrumental in predicting reservoir presence and their extent in the unchartered area of Sabah deepwater, which in turn can provide additional opportunity to explore in the frontier area in the future.
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NEW INSIGHTS ON BASEMENT INTERPRETATION OF NORTHEASTERN BAY OF BENGAL: IMPLICATION TO THE CRETACEOUS PETROLEUM SYSTEM
Authors H. Wahab, F.H. Darmawan and F.N. M KhatibSummaryThis paper aims to provide new insights of the basement interpretation in the Northeastern Bay of Bengal utilizing the newly acquired ∼14000sqkm hi-res 3D broadband seismic and gravity-magnetic data, hence evaluating its implication to the existing understanding of Cretaceous Petroleum System. The study incorporate the regional gravity and magnetic data in delineating the regional continental-oceanic boundary across the Bay of Bengal. The newly acquired hi-res magnetic-gravity data in the Northeastern Bay of Bengal are used for gravity-magnetic modeling in investigating the nature of the crust within the area of interest. Finally detailed qualitative attributes analysis and spectral decomposition on the hi-res 3D broadband data enabled a robust basement mapping
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SYSTEMATIC INTEGRATION OF GEOMORPHOLOGICAL CHARACTERIZATION AND QUANTITATIVE INTERPRETATION IN RESERVOIR DETERMINATION WITHIN THE MUD-RICH DEEPWATER DEPOSITIONAL SYSTEM OF NORTHEASTERN BAY OF BENGAL
Authors H. Wahab, T. Kurniawan, F.H. Darmawan and F.N. M KhatibSummaryImplementation of qualitative attributes generated from high quality broadband seismic data enables a higher resolution interpretation with variety of possible facies were identified in the data; i.e. Erosional/ leveed channel complexes, isolated single channels, fan lobes, MTC (Mass Transport Complexes) and drapes. The study identifies several types of deepwater depositional group, i.e. the channel complex High Amplitude Reflectors (HAR), unconfined channel flows High Amplitude Reflection Packages (HARPs) and turbidite lobes/splays. HARPs are visible directly above the erosional surfaces consists of remnants of abandoned channels with limited vertical aggradation. HARPs also can represents the transparent to chaotic MTCs. In addition, application of regional rock physics analysis, AVO analysis and seismic inversion modeling brings the quantitative value to the geomorphologic characterization and its potential reservoir fill via understanding of linked between rock properties and elastic properties. The study suggested that combination of p-impedance and VpVs remains as one of the critical quantitative elements due to ability to capture real element and character of the rock.
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NEARER, DENSER, LONGER: VARIABLE STREAMER LENGTH HIGH DENSITY TOWED STREAMER ACQUISITION TAILORED TO FULL WAVEFORM INVERSION AND HIGH-RESOLUTION IMAGING
Authors M. Widmaier, S. Naumann, G. Rønholt, D. O’Dowd and C. RoalkvamSummaryComplex geology, heterogeneous overburden, or a wide range of target depths makes the design of the optimal seismic acquisition solution and the corresponding imaging workflow more challenging. E.g., high-resolution imaging of shallow targets benefits from high density spatial sampling of the near offsets and broadband acquisition technology. On the other hand, imaging of deeper targets and the use of full waveform inversion (FWI) for velocity model building requires long offset recordings. In this case study from the Norwegian Barents Sea, we demonstrate the advantage of a novel acquisition solution that combines triple-source with a high density multisensor streamer spread and a variable streamer length. We evaluate the effect of long offset data on FWI, show how the updates can be extended to greater depths, and demonstrate the high-density acquisition for high-resolution imaging. We also elaborate on the future option to deploy the high-density streamer configuration with a wide tow source setup in front of the streamer spread, to further optimize imaging and AVO of shallow targets.
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LITHO-SEISMIC CLASSIFICATION BASED ON ELASTIC ROCK PARAMETERS AT “KELUARGA” FIELD, KUTAI BASIN, EAST KALIMANTAN USING PROBABILITY DENSITY FUNCTION APPROACH
Authors S.S. Widita, Sudarmaji, M. Nukman, D.B. Prabowo and H. KhairySummarySeismic reservoir characterization with litho-seismic classification method was aimed to map the sandstone probability. Simultaneous seismic inversion was performed using the PSTM (Pre-stack Time Migration) data from “Keluarga” field which is located at offshore Mahakam PSC. This study is able to analyze the probability of facies in the study area based on lithology classification from elastic rock parameters that gained from seismic inversion IP (P-Impedance), PR (Poisson Ratio) and its derivative of LambdaRho (LR) and MuRho (MR). Cross-plot between elastic rock parameters showed the lithology classification that fitted with its real model. The Probability Density Function (PDF) was used as the statistical approach to determine the lithologies probability and result in the lithology probability cubes. These outcomes are able to use for future field development.
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UNCERTAINTY IN MODELLING TOP SEAL AND FAULT SEAL CAPACITY
Authors R. Davies, D. Povey, M. D'Souza, N. Rahim Othman and G. IskenovaSummaryThis paper provides a novel approach for incorporating stratigraphic uncertainty modelled from well logs in determination of top seal and fault seal sealing capacity for basin and prospect scale analysis.
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USING SEISMIC SCULPTING, SPECTRAL DECOM AND RGB BLENDING TO IDENTIFY SUBTLE TRAPS AND DHI IN EAST MALAY BASIN
By J. ZhouSummaryMalay Basin is believed to still have significant HC potential in the stratigraphic and combination traps. A seismic sculpting workflow consisting of layer generation, spectral decomposition and RGB blending is proven very helpful in identifying more geobodies than found by amplitude response alone. It also helps in interpretation of depositional system and DHI identification. A total of 16 stratigraphic & combination traps and a missing pay were found in the AOI.
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MATURING POTENTIAL FRACTURED BASEMENT PLAY IN MALAY BASIN THROUGH REGIONAL INTEGRATED APPROACH
Authors R. Danial, N.H. Ngoc, J. Zhou, L. Jeevachandran, M.S. Abdullah, C. Shae Nee and M.A. FazilSummaryFractured basements play widely studied in the world of oil and gas exploration lately. Several hydrocarbon discoveries and fields exists around the globe. An intensive basement exploration campaign is required to achieve ‘a material impact’ on reserves to develop basement field. In southern part of Malay Basin, the basement play is proven based on the discoveries in Anding Field. The basement lithologies in Malay basin are relatively complex which consist of granitic, gabbro, diorite, dolerite, andesite, volcanic, basalt, limestone, sandstone, phyllite, quazite & argillite (metasediment). Few approaches been adopted such as data logging, core data, fluid data, seismic attributes to mature the basement play in the region.
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A FULL WAVEFORM INVERSION SCHEME FOR AUTOMATED SALT VELOCITY MODEL BUILDING
Authors F.S. Dzulkefli, M. Kalita, K. Xin, T. AlKhalifah and A.R. GhazaliSummaryIn area with the presence of complex large salt bodies results in a much more complicated and highly nonlinear inversion problem where we have multiple local minima with the possibility of having an ill-pose FWI problem. Current method typically pick the top salt, flood it and pick the bottom salt and include the manually developed salt in the initial velocity model. It requires a clear contrast boundary between the salt and the background sediments. This is not only time consuming but the manual interpretation is vulnerable to errors especially the bottom of the salt. An automatic velocity model building is a better alternative to manual interpretation and horizon picking. By applying FWI in two stages of model regularization namely, FWI+TV and flooding, we successfully implemented an automated velocity model building for salt body on SEAM 3D salt model. FWI+TV act as a penalty function to control the variation in the model while preserving the edges of the salt body and flooding smear the high velocity below the top of the salt across the region where there is a drop in the velocity with depth. The proposed method is more robust and less time consuming compared to the standard ‘migrate-pick-flood’ approach.
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UNCERTAINTY ANALYSIS IN ELASTIC AND ELECTRICAL PROPERTIES OF HYDROCARBON RESERVOIR: PITFALLS AND PROPOSE SOLUTIONS
Authors L. Luluan, M. Hermana, D. Ghosh and C. Weng SumSummaryFor the last decades, the seismic amplitude is the main tool for hydrocarbon predictions. Although seismic data provides subtle information about the structure and geometry, the sensitivity to hydrocarbon fluids is still limited. This paper presents the uncertainties and sensitivity analysis of seismic amplitude and other common elastic properties in discriminating the hydrocarbon fluids. We found out that almost all elastic properties failed in discriminating low hydrocarbon saturation. We present the pitfalls and propose solutions by for hydrocarbon reservoir discrimination especially on low hydrocarbon reservoirs.
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THE PRE OLIGOCENE NEW PLAY CONCEPT OF PENINSULAR MALAYSIA BASIN WITHIN THE REGIONAL GEOLOGICAL FRAMEWORK OF SOUTHEAST ASIA
Authors S.R. Iyer, M.H. Damanhuri, A.A. Azman and F. IliasSummaryMalay and Penyu Basins located on the eastern offshore area of Peninsular Malaysia are prolific petroliferous basins which are contiguous with the basins to the north in the Gulf of Thailand. These basins were formed during the Cenozoic extension along the regional Three Pagodas strike slip fault zone. The proven plays in Malay Basin are in the stratigraphic Groups M to B ranging in age from Oligocene to Pliocene and the older stratigraphy has been poorly documented due to very few well penetrations. Concerted efforts to rejuvenate hydrocarbon exploration in these mature basins led to the identification of a Pre Oligocene play spread over the southwestern flank of Malay Basin, Tenggol Arch and NE Penyu Basin. The sedimentary character of this new play is unequivocal based on the 3D seismic data in two N-S trending grabens on the Tenggol Arch, formed during an older phase of Early Paleogene or Mesozoic age, and is capped by a major regional unconformity. The new play is the likely southern equivalent of the poorly explored Mesozoic section of Phuquoc-Kampot Som Basin and Khorat basins to the north which developed as a foreland basin in response to the build-up of a Paleo-Pacific magmatic arc.
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PORE THROAT BASED ROCK TYPING AS A KEY TO UNDERSTANDING PERMEABILITY CONTROLS IN DIAGENETICALLY ALTERED CLASTIC RESERVOIR
Authors A. Belevich, C. Smart, J. Parlindungan Panjaitan, W. Gunary Abadi, A. Ertanto and Y. HendrayanaSummaryCharacterisation of porosity and even more critically permeability in diagenetically altered clastic reservoirs can be challenging and differs from conventional reservoirs. The challenge stems from the presence of multiple pore throat sizes. A number of processes can create these complex pore networks and a typical sand reservoir in Belanak field ticks most of the boxes in terms of complexity of pore morphology. Clay coatings, quartz overgrowth, carbonate cements and feldspar dissolution with secondary porosity, are universally present and occasionally coexist in key producing intervals. The link between rock quality and depositional environment does not exists in the studied reservoirs. These factors combined, created a complex assemblage of rock types, which are highly heterogeneous vertically and spatially. A simple power function porosity-permeability transform is not viable and will not allow efficient mapping of the best producing rock types. Reservoir rock typing (RRT) approach that takes into account the effect of pore-throat radius (PTR) on permeability is required. The ultimate objective of RRT development in this study was to (1) understand the spatial distribution of RRT, which are capable of flow and (2) make volumetric assessments of total connected net pay available within the oil rim to optimize well trajectories.
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RESERVOIR PROSPECTIVITY OF OLIGOCENE SYN-RIFT; CASE STUDY IN NORTH EAST MALAY BASIN, OFFSHORE PENINSULAR MALAYSIA
Authors R. Roslan, J. Zhou, M.R. Anuar, R. Danial, S.N.A. Sy Khastudin and N.A. A GaparSummaryEasier shallow clastic reservoir targets within Malay Basin have been depleted, and test of new play such as deeper reservoir is needed. PETRONAS Carigali is shifting the focus to explore the potential of synrift play in North East of Malay Basin. However, to date there is no significant commercial discoveries have been made from syn-rift play in Malay Basin.
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ACQUISITION AND PROCESSING OF CONTINUOUS WAVEFIELDS DATA - A CASE STUDY
Authors T. Klüver, S. Hegna, J. Lima and M. WidmaierSummaryIn summer 2018 a test survey was acquired offshore Brazil using a novel method based on continuous wavefields on top of a survey that had been previously acquired using a conventional dual source setup. The novel acquisition. In this paper, we describe the differences between the continuous wavefield method and the conventional method in terms of how the data sets were acquired, the environmental footprint of the seismic sources that were used, and the processing methods applied to the data sets. Finally we discuss the results obtained after 3D migration.
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ROCK PHYSICS AT-SCALE, ENABLED BY BIG DATA ANALYTICS & MACHINE LEARNING
Authors A. Mannini, N.M. Hernandez and F. BaillardSummaryRock Physics At-Scale, enabled by Big Data Analytics & Machine Learning
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WHY PEOPLE MATTER IN A SUCCESSFUL DIGITALISATION STRATEGY
Authors E. Andersen, A. Mannini, N.M. Hernandez and F. BaillardSummaryWhy people matter in a successful digitalisation strategy
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CHASING INTRIGUING SHALLOW CLASTIC PLAY IN SARAWAK OFFSHORE
Authors R. Yusupjanov, S. Nayak, S. Soed, A.J. B Che Johari and N.D.B. Adi AsokanSummaryGeological and geophysical studies have indicated considerable potential in shallow clastic play in Offshore Sarawak. A renewed approach with focused geophysical analyses with a robust regional geological model can unravel this promising upside hydrocarbon accumulations yet to be discovered in the Sarawak Basin. With pre carbonate and carbonate prospectivity become exhausted, shallow clastic holds the key for future exploration target.
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M-70 SAND: REALIZING THE GROUP M HIDDEN OPPORTUNITY IN MALAY BASIN
SummaryGenerally, marine petroleum system has been dominating global oil and gas exploration and production. Today, with Peninsula Malay sia’s marine giants have been widely discovered and produced, regional lacustrine petroleum system is gaining attention among local players. The M Sand in Malay Basin is of lacustrine setting and has always been associated with tight sand/formation due to the deep burial and compaction took place during the deposition. This scenario has indirectly discouraged the exploration focus on this group as it was believed to be economically unattractive. The objective of this paper is to share the challenges and hidden potential of Group M in Malay Basin focusing on risk and uncertainty management from exploration to development stage.
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RAPID EVALUATION OF RESERVOIR CONNECTIVITY IN A MULTI-STACKED SANDSTONE RESERVOIR FOR IMPROVE OIL RECOVERY PURPOSES
SummaryThis paper presents rapid techniques of reservoir connectivity evaluation in a mature oilfield with multi-stacked sandstone reservoir and recovery process involving waterflooding, through production and injection data analyses. The issue in waterflooding here is to understand the influence of water injection to oil production in complex reservoir geology. Hence, accurate interpretation of reservoir connectivity is critical to have high flow efficiency. Prudent reservoir management often requires fast solution to evaluate and subsequently improve the efficiency of the on-going waterflooding performance and also for tertiary recovery purposes. Therefore, dynamic data analytics workflow applying Pearson’s Correlation Coefficient (PCC) interwell connectivity technique verified with Streamline is proposed. The PCC and Streamline techniques are able to provide rapid framing analysis of reservoir network incorporating production and injection data. Both techniques can identify areas with good or poor connectivity, injection efficiency and barrier/sealing fault in relatively short timeframe (weeks). Identification of these areas can provide important information for reservoir characterization, reservoir dynamic behaviour and reservoir management plans. It can be utilized as an efficient tool for management to decide strategic business decision to improve oil recovery through waterflood optimization and enhanced oil recovery processes.
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HIGH-RESOLUTION FULL-WAVEFORM INVERSION FOR STRUCTURAL IMAGING IN THE MALAY BASIN
Authors H. Tan J, S. Zainal, H. Mohamed, P. Soo K, C. Lam C, S. Maitra, R. Alai, M. Zohdi S F B, B. Danial R, B. Roslan R, A. Aziz S S B, B. Ghazali M and S. DhanapalSummaryConventional velocity model building methods like ray-based tomography are not optimal in the shallow water environment due to lack of usable near offsets. Full-waveform inversion (FWI) can be an effective model building tool, particularly in Malay Basin where presence of shallow gas bodies and shallow channels posed several imaging challenges. In this paper, we exhibited that joint refraction and reflection FWI can produce improvements in seismic images and provide high resolution velocity model that can aid interpretation.
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LEAST SQUARES Q PRE-STACK DEPTH MIGRATION: A LEAP FORWARD IN SEISMIC IMAGING OF COMPLEX SUBSURFACE STRUCTURES
Authors L. DoH, C. Lam C, L. GhazaliM, S. Maitra, A. Bisset, L. AlfredS and M. MasatoSummaryStandard Kirchhoff Q Pre-stack Depth Migration (QPSDM) can help to compensate for the amplitude decay, phase distortion and resolution reduction. However, the increased migration noise associated with QPSDM process still remains a challenge. With recent advances in high performance computing and algorithms, Least Squares Q Pre-stack Depth Migration (LS-QPSDM) has become a viable solution to overcome existing shortcomings of conventional QPSDM. Compared with conventional QPSDM, LS-QPSDM combines the benefits of both Least Squares Migration and QPSDM to improve the amplitude fidelity and image resolution of the seismic data.
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HIGH-RESOLUTION BIOSTRATIGRAPHY: ITS IMPACT ON RESERVOIR MODELLING, A CASE STUDY FROM THE MALAY BASIN
Authors S. Noon, S. Rahmad, M.T. Nguyen, S.L. Chan and S. Mhd. SabohiSummaryAn integrated reservoir description project was designed to help reduce uncertainty and define the conceptual model/static model for five wells. The study was focused on a Middle to Early Miocene incised channel fill. A 53m core was closely sampled to provide a ‘type section’ for the reservoir. High-resolution biostratigraphy shows that the reservoirs and bounding shales/claystones were deposited in coastal settings with shallow marine environments of deposition indicated both above and below fluvial to intertidal reservoir sands. Accomodation space for deposition of the reservoir was likely to have been initially created by tectonic uplift leading to incision, but a possible eustasy-driven sequence boundary is seen towards the base of the channel-fill. For modelling purposes the interpreted depositional model derived from biostratigraphy/biofacies was divided into fluvial dominated, and tidal dominant settings. A depositional facies modelling approach was then applied and two main reservoir zones: Zone 1 and Zone 2 were defined. Sedimentological core description and all other available datasets including well logs, core analysis, seismic attributes and biofacies-based high-resolution biostratigraphy, seen in the context of modern ecological and geographic analogues, proved to be crucial for enabling the development of an effective static model which in this case-study validates reservoir simulation results.
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APPLICATION OF ADVANCED DEEP DIRECTIONAL RESISITIVITY IN COMPLEX RESERVOIR CHARACTERIZATION – A CASE STUDY FROM MALAY BASIN
Authors S.H. Samsuddin, R. Rahman, K.W. Poh and C.L. LaiSummaryThe I45 reservoir is a channel system which consists of multiple stacked sand-bodies with complex internal geometry that result in multiple fluid contacts. The complex reservoir architecture and sub-seismic features make reservoir modeling and well planning a challenge. However, on the horizontal well which was recently drilled, an advanced deep-directional resistivity tool was used to help optimize well placement. On top of that, this tool also helped resolve some uncertainties about the internal architecture; it helped confirm and map the presence of a shale-filled channel. This knowledge, once incorporated into the static model, ultimately provided a robust reservoir model that matched the reservoir performance better.
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REGIONAL AND LOCAL STRESS ANALYSIS USING BOREHOLE IMAGE INTERPRETATION - INSIGHT FROM SOUTH SUMATERA
Authors M.Z. Mohd Nasir and M.H. MohamadSummarySouth Sumatra Basin is one of the mature basin in Sumatra, Indonesia. Exploration started in South Sumatra Basin as early as 1886 by discovery of Kampung Minyak Field (Macgregor, 1995). Since then, numerous exploration and production activities have been done for both conventional and unconventional plays. The Basement play had become significant play with major gas discovery in the Corridor PSC and these fields have been produce since 2001 until now. Understanding the natural fracture networks is crucial to determine the reservoir effectiveness for the hydrocarbon production from fractured basement formation. The uncertainty and main risk dealing with basement reservoir which fractures and fault contribute to open or conductive fractures. Thus, determining which fracture open is crucial. In-situ stress regime plays the important role to recognize the effective porosity and permeability of fractured basement. Several studies on the tectonic and stress field have been conducted (e.g. Mount and Suppe, 1992; Tingay et al, 2010 ) which largely focused on present-day stress orientation from well data. It is due to inability to map the small faults and fractures using seismic data. Using well data, critical stress and maximum horizontal stress can be determined from the conductive fractures and borehole breakout respectively.
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PUSHING THE BOUNDARIES OF SHALLOW WATER, LIMITED OFFSET DATA USING ADVANCED IMAGING METHODS FOR PRE-CARBONATE IMAGING
Authors A. Latib H, S. Zainal, H. Tan J, K. Syah M, S. Maitra, H. Lim C, W. Hoong T, A. Bapu M and D. Woei ASummaryOne of the preferred cost-effective solutions when searching for deeper, pre-carbonate targets in a marginal field is by reprocessing of a vintage seismic dataset using the most current state-of-the-art processing technology. The vintage data in our study area suffered from amplitude loss due to seismic signal absorption and distortion by complex multi-layer high absorption pre-carbonates and gas clouds, causing discontinuous deep seismic reflectors at the target zone. Careful noise and multiple elimination around the carbonate layers was critical for proper imaging of deeper fault systems. Despite the limited offset and narrow azimuth data, current advanced imaging technologies managed to reveal the reservoir.
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CENTRAL LUCONIA CARBONATE RESERVOIR SWEET SPOT IDENTIFICATION OF LANG LEBAH-1(RDL2)
SummarySarawak exploration’s creaming curve, mainly dominated by dry natural gas, is still rising from recent discoveries in the Late Miocene platform carbonates and pinnacle reefs of Central Luconia sub-basin. The geological province of Central Luconia extends over 40,000 sq.km with more than 200 carbonate build-ups ( Longman, 1993 ), which grew on regional and local highs of deep graben structure. PTTEP acquired exploration block namely SK410B in 2016, and completed 3D broadband seismic acquisition in 2017. In order to successfully explore remaining hydrocarbon potential in a mature basin, comprehensive exploration approach for well targeting in carbonate reef is established. The approach requires integration of comprehensive result of reservoir characterization using seismic quantitative interpretation (rock physics and seismic inversion), and carbonate growth architecture identification. The multidisciplinary approach then referred to the sweet-spot targeting for carbonate build-up appraisal program.
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OVERCOMING CHALLENGES OF CONVERTED WAVE IMAGING IN THE PRESENCE OF STRONGLY ANISOTROPIC, HETEROGENEOUS MEDIA
Authors F. Basir F, S. Maitra, G. Wang, S. Zainal, L. Ghazali M and R. Ghazali ASummaryConverted wave imaging has been proven to be able to provide a complementary subsurface image to conventional P-wave imaging. This dataset from offshore Sarawak, Malaysia, suffers from strong gas absorption effects on the P-wave image because of which 4C OBN data was recorded. Due to the wide azimuth nature of the OBN data it was apparent that the area also experiences strong azimuthal anisotropy due to a compressional stress field in the region. PS imaging suffers greatly under these geological and structural complexities and requires careful handling. This paper describes pre-processing and imaging efforts to mitigate illumination, azimuthal and velocity modelling challenges and produce a high quality PS image.
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PRE-SALT IMAGING ADVANCEMENT AND CAPTURING UNCERTAINTY OVER RESOURCE ASSESSMENT
Authors W.C. Low, M. Mohd Nor, G. Coskun and J. IsmailSummaryStatistical analysis comparison has been carried out based on the mapped depth of the structural crest, structural spill, structural area and gross rock volume of 25 structures, across the basins of various geological domains and different seismic vintages.
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PORE PRESSURE PREDICTION BASED 3D TOMOGRAPHIC INVERSION VELOCITY MODELING FOR LANG LEBAH-1(RDL2)
SummaryOne of the main operation challenges exploring carbonate reservoir in Central Luconia is the high pressure environment. Therefore, pore pressure prediction is one of the most important inputs required for more efficient casing design, accurate mud-weight estimation, and safe operation preparation for each reservoir section.
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OLIGOCENE TO RECENT STRUCTURAL EVOLUTION OF NORTH SUMATRA BASIN
Authors M. Muchlis and C. EldersSummaryFaults that formed the basin boundary fault were created during extensional evens in the Oligocene. During the late Miocene the NSB experienced compression where fold structures were formed. In addition some extensional faults were also reactivated at this time which caused the formation of inversion structures. By contrast, interpretation of offshore 2D seismic lines shows that the major faults (the basin bounding fault system) are oriented north-south. These faults are also Oligocene in age and are controlled by extensional events. Fold structures formed during the late Miocene and younger. However, there is also fold structure that formed during the Oligocene in the western part of the offshore. During late Miocene-early Neogene the offshore North Sumatra Basin also experienced minor faulting that is expressed by small normal faults.
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CLUSTER DEVELOPMENT CONCEPT: NEW APPROACH FOR MALAYSIA MARGINAL FIELDS
Authors S. Pernsantia, P. Siriyoot, A. Suphawajruksakul and S. ThanudamrongSummaryRegarding various types of the studies such as the depositional environment from sequence stratigraphy study, fault seal analysis, structural analysis and amplitude attribute study, they indicate the dependency of each compartment. As this, PTTEP integrates all results of the studies to build the concept to support cluster development model and with this concept, it will enable PTTEP to develop many marginal fields.
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UNDERSTAND THE CARBONATE HETEROGENEITY TO EFFECTIVELY EXPLORATION AND DEVELOP CARBONATE PLAYS IN SOUTHEAST ASIA
By F. XueSummaryCarbonate heterogeneity is extreme and extensive and has significant impact in carbonate exploration and production. But due to limited knowledge and approaches on carbonate heterogeneity, carbonate E&P operations are much under-performed, which have left large potential unrecognized in carbonates for exploration and development, even in many mature fields/areas. Based on carbonate characters, the opportunities in carbonate E&P at Southeast Asia are grouped into four types for discussion.
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BORNEO ALTERNATIVE MODEL - BORNEO INDENTION (PART 1 SABAH)
More LessSummaryAn Alternative Model for Sabah NE Borneo Tectonic is proposed, namely Borneo Indention. The model propose significant tectonic stress originated from collision of Pacific and Australia Plate, resulted into indentation tectonic observed on onshore and offshore NE Borneo.
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MULTI-COMPONENT STREAMER DESIGN; CURRENT STATUS AND THE WAY FORWARD
Authors N. Goujon, S. Rentsch, L. Combee, F. Guizelin and K.F. AhmadSummaryThe design of towed streamers has been optimized over the years to deliver high-quality pressure data from hydrophones. More recently, new multicomponent towed streamers have been introduced to the market, where particle motion is measured in addition to the pressure. Because particle motion sensors directly measure the vibration modes generated in a cable under tow, this introduces new constraints on the design of towed streamers. To study the impact of the streamer mechanical construction on the characteristics of the vibration noise, we have built streamer sections with dense point receiver sampling, identical electronic backbone and MEMS sensors, but different mechanical properties. We towed them together under different tensions in a fjord experiment. We observed that, as expected, the transverse vibration noise was the dominant noise mode, with dispersion characteristics depending on the streamer bending stiffness. We also found that the noise amplitude and maximum frequency depends on the mechanical properties of the cable, and that they could be reduced by using a new type of gel optimized to dampen vibration. Based on these findings, we see an opportunity to design a cost-efficient multicomponent streamer combining an optimized mechanical platform with a new single sensor configuration.
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THE DIGITAL GEOSCIENCE REVOLUTION – WHERE ARE WE NOW?
Authors S.J. Buckley, N. Naumann, K. Ringdal, B. Tong, J. Vanbiervliet, M. Chmielewska, G. Maxwell and J.A. HowellSummaryThis abstract will cover the latest developments in digital outcrop modelling, showing how the convergence of disciplines and advances in technology are allowing us to realise the early potential shown in the early 2000s with the advent of lidar. The contribution will show how geoscientists are adopting digital outcrop methods in unprecedented numbers, and that challenges are still evident that should be addressed. We will illustrate the topic with three showcase examples: combining digital outcrop modelling with seismic modelling, the SAFARI outcrop analogue database, and preparing virtual field trips by combining many geoscience data sources.
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G-FIELD – A NEW WAY FOR IWRS IN BROWN FIELDS: REDRILLS
Authors F.J. Heng, A.F. Mohamed Isa, C. Chew, C.Y. Chiu and S. HamzahSummaryThe paper demonstrated an alternative way of developing a mature field at a cheaper cost, and improved production rates
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3D SEISMIC INTERPRETATION AND MAPPING OF THE UPPER MIOCENE – LOWER PLIOCENE KELIDANG FAN, DEEP WATER OFFSHORE BRUNEI: A NEW PLAY ILLUMINATED THROUGH INTEGRATION OF SEISMIC ATTRIBUTE AND GEOLOGY
Authors N.A. A Ghafar, C.W. Rudiana, S. Chee At Saad, M.A. Hj Ismail and M.I. Megat IsmailSummarySubsurface of ultra-deep water Brunei Darussalam has remained untouched since the petroleum exploration began in the country. The ultra-deep water area, which is to be discussed in this paper, was considerably a frontier area with major risks was on reservoir presence and hydrocarbon charging. Reservoir remained the major risk until the Late Miocene-Early Pliocene sand rich turbidite fan namely the Kelidang fan was discovered. The area, in which Kelidang fan is located, has been receiving sediments mainly from two delta systems namely the Champion delta and Baram Delta. However, this extended abstract mainly focusses on the sequence that was sourced by the Baram Delta. From the 3D seismic interpretation, it shows that the Kelidang fan extends some 60km into outboard offshore Brunei and has been transported via narrow deepwater channel systems linked to the 5.3Ma paleo-shelfal canyons at the edge of Baram delta. Interpretation and analyses on technical data shows that the paleo-settings and structuration of continental shelf, slope, basin floor and massive deposition of mass transport complexes played roles in defining the delivery system of the Kelidang fan.
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IMPROVING OLD SEISMIC USING FULL WAVEFIELD INVERSION AND BROADBAND PROCESSING: IMAGING COMPLEX STRUCTURES UNDER SHALLOW GAS
Authors G. Chen, V. Gudipati, S. Jaynes, T. Jenkinson, S. Lee, J. Reilly, S. Lazaratos, R. Neelamani, A. Martinez, A. Zulfitri, F. Onn, C. Shaw, A.R. Ghazali, A.A. A. Khalil and N.H. NghiSummaryA case study is presented wherein broadband processing, FWI and Q migration have been used to address poor imaging due to complex-overburden and amplitude-loss. The area of study is a producing oil field in offshore Malaysia, where seismic imaging was impacted by extensive shallow gas accumulations. OBC and streamer data were used to produce high-resolution subsurface velocity models via FWI. Our results show that modern processing methods combined with FWI can provide significant imaging uplift and reduce interpretation uncertainty, even with seismic data that are decades-old.
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SPARSE CL-SRME USING IMPULSE RESPONSE AND SOURCE WAVELET: METHOD AND APPLICATIONS
Authors H. Hashim, A.R. Arshad and A.H. Abdul LatiffSummaryWe proposed a new approach for multiple removal using the CL-SRME method. Instead of directly updating the estimated primaries, we update the impulse response and the source wavelet together during inversion as both are used to defined the primaries estimate. Through imposing the sparsity constraint toward the update of the primary impulse, we can obtained the spiky primary impulse and reduce the time for its convergence. With an example from both synthetic and field data of Malay Basin, it shows that this new approach works on both shallow and complex geological area. One advantage of using the new approach is it were able to recover the primaries continuity which are often missing due to primaries-multiples overlap. The faster rate of convergence also proves that this new approach could be an alternative to EPSI or CL-SRME.
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EVOLUTION OF LATE QUATERNARY SARAWAK SHELF: A SEISMIC GEOMORPHOLOGIC APPROACH
Authors S. Nayak, N. Pendkar, S.F. Jabbar and A.J. Che JohariSummaryThis paper presents results using the extensive 3D seismic data from Sarawak offshore to characterize geomorphic features and understand changes in depositional environment using shallow seismic data within 500 ms from sea bed. Well-developed fluvial channels and incised valleys identified in seismic time-slices represent exposure of Sarawak Shelf during later Quaternary time. The current study also identifies prominent fluvial river systems throughout Sarawak shelf using 3D seismic data. Presence of numerous rivers of different shapes and sizes points to exposure of Sarawak shelf during sea level fall during Late Quaternary age. Some of the river valleys could be traced for more than 200 km. Presence of large scale incised valleys with prominent tidal inlets refers to sea level lowering below shelf edge exposing the whole shelf. Few consecutive time slices from a survey have been presented to demonstrate dynamic changes of depositional elements because of sea level variations throughout Sarawak shelf. Geomorphic features mapped and the broad EOD patterns recognized in the study can be used to understand sediment dispersal pattern in a coastal plain environment. These features could be used as analogue to the deeper hydrocarbon bearing Cycle I reservoirs of Sarawak basin, which were deposited in similar coastal plain environment.
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MINIMIZING DEPTH UNCERTAINTIES BELOW GAS CLOUD: TIME-TO-DEPTH CONVERSION TECHNIQUE
Authors A.G. Mohd Adnan, U.F. Ungku Farid, M.A. M Ishak and A. AzmiSummaryThis paper presents a new way to address one of the current challenge problems in geoscience within Malaysia; namely, Shallow gas effect for hydrocarbon exploration in Malaysia. The presence of shallow gas in the overburden can distort and negatively impact the seismic image quality underneath the gas affected area. These images below clouds are usually not properly imaged due to the complex wave propagation through the gas body, for instance, dispersion, scattering, internal multiples, mode conversion during wave propagation, and possibly anelastic losses. This method takes into consideration both seismic velocity and wells, and it takes into consideration both seismic velocity and wells, provided that there are wells penetrating the gas clouds. For best results when dealing with structural and geological complexities, PSDM with wells will provide the ideal depth conversion results
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SUBTLE INFORMATION THAT BRINGS VALUE: GEOLOGICAL BARRIERS REVEALED THROUGH DATA INTEGRATION
Authors C.L. Lai, C.M. Pang, F. Fahmi and R. Abdul RazakSummaryThe B reservoir was initially interpreted as a meandering channel system, observed on seismic data. Subsequently, wells were drilled to further appraise and produce the reserves from this reservoir. However, after several years of production, reservoir simulation history matching suggests that the reservoir production does not behave like a single tank. Pressure transient analysis suggests that there exists a partial barrier that isolates the production around Well-21. Reservoir engineering studies have also inferred the locations of potential barriers, a certain distance from Well-21. Further analysis are then performed on the seismic dataset to identify these potential barriers that would explain the production history. In this example, the application of spectral decomposition managed to identify several channel features that is cutting across the main reservoir. After several iterations of reservoir model updates, some of these potential barrier features are in locations that are consistent with reservoir engineering analysis. The reservoir models have since been updated and new infill well locations were identified, further maximizing the value of the B reservoir.
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