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APGCE 2019
- Conference date: October 29-30, 2019
- Location: Kuala Lumpur, Malaysia
- Published: 29 October 2019
1 - 50 of 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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