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APGCE 2019
- Conference date: October 29-30, 2019
- Location: Kuala Lumpur, Malaysia
- Published: 29 October 2019
41 - 60 of 99 results
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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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