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Asia Petroleum Geoscience Conference and Exhibition (APGCE)
- Conference date: November 28-29, 2022
- Location: Kuala Lumpur, Malaysia
- Published: 28 November 2022
21 - 40 of 132 results
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Empirical Detection of Suppressed Vitrinite in Legacy Data: an Example from the Malay Basin
Authors M. Madon, J. Jong and N. Dayang AimiSummarySuppressed vitrinite reflectance (Ro) can have a big impact on exploration decisions if not recognised and corrected for. It is known to occur in the Malay Basin where optically determined Ro values have been compared with equivalent Ro analysed by the FAMM (Fluorescence Alteration of Multiple Macerals) technique. Although “apparent” suppression of Ro may be minimised through strict laboratory protocols, explorationists may have to deal with legacy data (say pre-1995) comprising only optically determined Ro of unknown quality. How then would suppression be detected? In this paper, we examine both Ro and FAMM data in the Malay Basin to see if a general suppression trend can be established and consider its potential implications for exploration.
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A Review of the Structural-Stratigraphic Framework and Petroleum Systems of the Sandakan Basin, offshore East Sabah
More LessSummarySandakan Basin, located offshore East Sabah, is one of the few regions in Malaysia that have yet to produce commercial hydrocarbons despite decades of exploration effort. The exploration history and hydrocarbon occurrences in the area up to year 2000 have been summarised by Leong & Azlina (1999) . A number of sub-commercial discoveries have demonstrated the presence of a generative petroleum system in the offshore Sandakan Basin between the Sandakan and Dent Peninsulas. These occurrences complement the numerous oil and gas seeps commonly associated with mud volcanoes and salt springs, especially on Dent Peninsula (e.g., Leong & Azlina, 1999 ). This paper provides an updated overview of the structural-stratigraphic framework and petroleum systems in the basin.
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Alteration of Mudrocks by CO2
Authors M. Sams and T. JayasangarSummaryAnomalous features observed in seismic data from parts of the Greater Sarawak Basin are believed to be diagenetic fronts associated with the presence of CO2. Measurements from well log data show that the elastic properties of shales and silts behind these diagenetic fronts have been altered through a loss of capillary bound micro-porosity. It is hypothesized that this is due to the action on the clays of carbonic acid, which diffuses along a concentration gradient away from the reservoir rocks, which contain high concentrations of CO2 that have accumulated in traps along with hydrocarbons. The velocity and density data can be corrected based on an empirical model that matches similar changes caused by normal mechanical compaction. The degree and shape of the alteration is sufficient for these effects to be observed on seismic data. The amplitudes and AVO characteristics of the seismic data drastically change due to the alteration thereby making reservoir and fluid prediction significantly more challenging. The alteration might be used as an indirect hydrocarbon indicator as there is a strong correlation within the current data between hydrocarbon presence and shale alteration.
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The Shaping and Demise of the Tusan Beach “Drinking Horse”, Southwest of Miri, Sarawak
Authors M.H. Bin Yussof, J. Jong and F. KesslerSummaryThe Miri-Bekenu coastline is formed by Neogene clastic rock formations that are poorly consolidated. These formation outcrops are shaped by weathering elements of tropical rainfalls, wind and marine erosions, and deformation processes such as tectonic uplift, structural faulting and folding. The geological monuments of the Miri area such as the iconic Tusan Beach “Drinking Horse” cliff structure generally withstand weathering degradation and marine erosion poorly. Further to this, housing projects, road constructions and encroaching new plantations had their share in destructing geological landmarks. In this article, we discuss the case study of the “Drinking Horse” starting from its creation, the impact of weathering elements and coastal erosions, and human interferences that resulted in its ultimate demise. Nonetheless, due to its present-day state of seaward-dipping sedimentary layers prefect for gravity sliding, coupled with pounding erosions, the cliff had inevitably collapsed and any prior preservation effort carried out to protect the structure were seen in vain.
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Seismic Imaging Workflow Optimization and Velocity Model Uncertainty Quantification in Carbonate
Authors M.H. Pua, M.I. Supardy, C. Lee Slind, W.H. Tang, S. Maitra and F.F. BasirSummaryThe velocity Model plays a remarkably important role in seismic processing, especially in seismic imaging, as it directly affects the final data quality. Carbonate fields velocity model building are even more complicated as they are known to be much more complicated in chemistry and physics that leading to high heterogeneity and uncertainty. Often in carbonate fields, other complications also will associate together such as shallow gas in this case study where it increases the complexity and difficulty to obtain the most optimum velocity model for seismic imaging. This accumulation of complications can be resolved mostly through advanced and modern seismic processing techniques however, there will be still some uncertainty remaining in the velocity model building. In this case study, a tailored imaging workflow that includes Q-tomography, Q-APSDM, and FWI has been applied and plays an important role in solving most of the challenges while optimizing the velocity model. The uncertainties that underlie the velocity model produced even with this sensible workflow will still be present and need to be quantified. The quantification of velocity model uncertainty will be through the tomographic inversion process and able to provide velocity standard deviation as an output that reflects velocity model uncertainty.
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Upgrading and Redefining Cycle I GDE of Deepwater Sarawak via Multi-Attributes Analysis of Cycle I Coal
SummaryThis study covered within North Luconia region which warrant a guidance towards Cycle I gross depositional environment (GDE) revision. Previous model of 2020–2021 Cycle I GDE represent separated bodies at Well C-1, Well O-1, Well P-1, Well Q-1 and Well R-1 due to those wells was sitting at paleo high as supported by Bouger anomalies and was affected by marine incursion. In general, coal deposition in Cycle I was associated with lower coastal plain (LCP). However, the coal deposition in the previous model was not extensive and this therefore, raised a possibility that it might be a single coastal body instead. Questionable on the swampy area which only pointing at Central Luconia while at North Luconia province, the coal still can be established as depicted by Well A-1, Well C-1, Well J-1, Well O-1, Well P-1, Well Q-1 and Well R-1.
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Uplifting Vintage 3D Land Seismic Dataset with Modern Processing Workflow: a Case Study from Thailand
Authors N. Wanpiyarat, R. Chakraborty, S.H. Ng and N. PhantaweeSummaryWe present a case study based on the application of modern contemporary signal processing and depth- imaging techniques to vintage data from the Phitsanulok Basin, onshore central Thailand, in which four overlapping vintage 3D land surveys were merged and imaged pre-stack to form a single volume. The vintage data processing was limited to the application of dip-filter-based noise attenuation, pre-stack time imaging and post-stack survey merging, which leads to unresolved geophysical challenges associated with each process. In the reprocessing, a cascaded application of surface-wave and coherent noise attenuation was followed by surface-consistent deconvolution that is robust against surface-inconsistent noise and suitable for stabilizing the amplitude and phase response of the embedded wavelet. 5D matching-pursuit Fourier interpolation technique was utilized for interpolation and regularization in offset-vector tile domain of the sparsely and irregularly sampled data. Anisotropic depth imaging was implemented to reduce the structural uncertainty. Additionally, pre-stack merging of the vintage seismic data facilitated accurate structural imaging in and around the overlap area of the surveys. The improvement attained in the reprocessed seismic images will reduce the risks associated with future development plans, overcoming the limitations of the suboptimal acquisition parameters.
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Understanding Stage IVD-Pink Reservoir through Hard Data-detailing Geoseismic, Integration of Updated PDA and Newly Constructed GDE
SummaryThe distribution trend of Stage IVD Pink is matches with the shelf edge cut in Southeast to Northwest direction which suggesting the entry point is coming from Baram and Champion delta. During syn-kinematic deposition of Stage IVD Pink, the sand transportation tries to find the lower structure as a main pathway towards distal toe-thrust area. The Stage IVD Pink behavior is deposited during syn-kinematic event where the deposition takes place during structuration forming ponded turbidites. Based on well and biostratigraphy analysis at Stage IVD Pink, it is correlatable to NN11/NN10. Seismic facies summary demonstrates 8 seismic facies categories interpreted in the area. The new analysis of Stage IVD Pink PDA covered 22 wells constrained within area of interest and failure analysis is generated based on 9 wells (excluding discovery and unevaluated wells) PDA shows reservoir as the main causes of exploration failure due to previous wells drilled targeting crestal part of toe-thrust area. Pink interval is deposited during syn-kinematic phase, hence thicker sands is believed to be deposited at the flank area and thinning onto the crest. The distribution of Stage IVD-Pink reservoir is limited towards distal toe-thrust as shown by NN11/NN10 zone at well 23-1.
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Chasing the Remaining Hydrocarbon in Carbonate Build-Ups of Central Luconia Field, Offshore Sarawak, Malaysia
Authors Z. Abdul Rahman, J. Baharom, N.F. Zawri and S.S. Ab RahmanSummaryOpen-winged carbonate platform characterised by thin carbonate wings were interpreted to have been deposited in situ as a thin carbonate platform during marine transgressions. 3D seismic data of the Terumbu Luconia covering an area of approximately 13,483 km2 was used in this study. The advancement in the interpretation technology allows extensive number of seismic horizons to be picked and mapped with consistent polarity. Seismic interpretations revealed that the open wings tend to extend for several kilometres away from the buildups along flat-lying surfaces and may have volumes significantly larger than the volumes of their corresponding buildup intervals. Central Luconia province is one of the major producing areas in Sarawak fields with almost 250 fields and 65 tcf recoverable gas discovered to date. However, most of the producing wells targeted to the main long-lived carbonate buildups. The results indicated that there is promising gas potential for NFE exploitation in the allochthonous play within the study area for further evaluation.
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Detached Offshore Bars. Testing a Stratigraphic Play, Offshore Sarawak, Malaysia.
SummaryOffshore bars are an enigmatic and often under-recognized constituent of the shallow marine deposition system. In the Pliocene aged, Cycle VI clastic sedimentary succession located offshore Sarawak Malaysia, offshore bars have been interpreted from sediments previously thought to be lower-to-middle shoreface deposits. The reclassification of these sediments from shoreface to offshore bars yields compelling exploration opportunities as detached bars, encased in shelfal mudstones may constitute stratigraphically isolated traps.
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Unlocking Significant Hydrocarbon Potential with Newly Identified Carbonate Play in North Luconia, Deepwater Sarawak, Offshore Malaysia
SummaryThis abstract presents the recent G&G work which led to identify Carbonate Play in North Luconia province deepwater area of Sarawak, offshore Malaysia. North Luconia, offshore Sarawak is a relatively frontier area for exploration having very sparse well density and presently low exploration activities. The understanding of petroleum system elements in this area is relatively fair to good. In the past most wells drilled in Northern Luconia deep-water, targeted Cycle I and Cycle II Clastic reservoirs. There are few wells drilled to target deep-water turbidites sands in Cycles V–VII. So far, no commercial hydrocarbon accumulation has been encountered, however there are few sub-commercial discoveries made in the region, have proven working petroleum system. Recent interpretation of Seismic 3D PSDM data leads to identification of a potential Pre-Cycle I ( Sequence-A Carbonate Play) in Late Eocene - Early Oligocene age. The integration of other G&G data, i.e., seismic, wells, and Gravity-Magnetic have been made to identify prospects in Sequence-A Carbonate Play in PETRONAS Carigali operated Blocks ND1, ND2 and ND3. Preliminary evaluation of Sequence-A carbonate play indicates evidence of huge hydrocarbon potential in deepwater area of Sarawak, which will certainly rejuvenate exploration activities in this region.
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Revealing the Reservoir Underneath Volcanic Rocks and Folding Structures in the Liaohe Basin
More LessSummaryMultiphase volcanic eruption and fault-related folding form good traps for hydrocarbon reservoirs in Liaohe-basin, China. Exploration activities in the deep Paleozoic section in the region have been limited due to poor subsurface imaging underneath complex overburden. Strong surface-related multiples are present, because of frozen surface conditions and high impedance contrasts between sediment layers and volcanic rocks. These multiples overwhelm weak primary signals in deep section. Meanwhile, drilling history revealed high spatial variation of the velocity in deep target zone due to major faults and volcanic rocks. Such complex overburden poses significant challenges for seismic imaging. Imaging is further complicated by the inadequacy of available data sets, which all have narrow-azimuth coverage and limited offsets. None of these challenges have been fully addressed in the vintage seismic processing. In this study, we first demonstrate the importance of 3D surface-related multiple elimination (SRME) after adaption for the data here, and then present iterative time-lag full-waveform inversion (TLFWI) to derive an accurate high-resolution velocity model that can correct the kinematic distortions due to the complex overburden. With a tailored flow, the Paleozoic section and the major Rongxi reverse fault are clearly revealed in our latest re-imaging, which helps reduce uncertainties for future exploration.
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Advanced Geostatistical Seismic Reservoir Characterization in the Growler Field
Authors A. Mannini, S.J. Yap, D. Cunha, E. Shirley, J. Zhou, A. Mathur, A. Mandong, R. Shaw and J. TingSummaryThe Growler field located in the Cooper–Eromanga Basin, South Australia, is an onshore field producing oil from the middle Birkhead formation of Jurassic age. The main producing area is a low relief four-way dip closed structure consisting of a channel reservoir of 15–20m thickness that has been mapped from the 3D seismic amplitudes and confirmed by the drilled wells. Interpretation of 3D seismic data has revealed relatively lower quality oil reservoir in the form of minor sandstone channels and crevasse-splay deposits. To draw strategy for optimum development of this field and to support further exploration campaign pre-stack seismic inversion has been carried out. An innovative workflow comprising iterative seismic petrophysics, rock physics modelling, preconditioning of seismic data was used to calibrate the seismic AVO response with well data. Deterministic inversion was carried out and litho-facies estimated using Bayesian inference to understand the intricacies of the aforesaid challenges before application of geostatistical inversion to derive highly detailed subsurface model. Joint facies and elastic properties inversion facilitated by geostatistical inversion using Markov Chain Monte Carlo method has resulted in good quality facies results that match wells at several blind locations and conform to the depositional setup of the area.
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Why Subsurface Uncertainties don't have to be Lognormal and other Practices to Avoid
By J. De JagerSummaryThe risks and volumes of oil and gas prospects are in most companies assessed in commercially available probabilistic Risk & Volume tools. Despite a lot of effort is put into this, the exploration community continues to over-predict (on average) the oil and gas volumes of prospects. This is in part due to some misunderstandings that lead to common practices that are best avoided. In this presentation several of these will be discussed: the incorrect assumption that subsurface uncertainties must be lognormal, incorrect truncation of uncertainty distributions at the low end, and the way that uncertainty is often confused for risk. A better understanding and application of these basic aspects of sound Risk & Volume assessments may reduce the risk of over predicting prospect volumes.
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Decomposing Zoeppritz: A Visual Interpretation of AVA
Authors M. Sams and T. KurniawanSummaryFor most people, the Zoeppritz equations are impenetrable and provide a barrier rather than an aid to interpreting seismic amplitudes in terms of key reservoir properties. Even very basic simplifications can be challenging for some. AVA blocky modelling is commonly used to visualise the AVA behaviour of half spaces, but these only provide limit use for the complexity of most geological situations where vertical variations are occurring at many scales. We propose that a deeper understanding of the AVA behaviour of seismic data is better achieved by visualising synthetic AVA gathers based on well log data, which have been decomposed into three terms representing the response to variations in acoustic Impedance, shear modulus and density. The decomposition shows how the AVA is governed by the vertical variations in the elastic properties and the inter-relationships between those elastic properties. These insights will allow the interpreter to more readily make the link back to the geology and the quantitative interpreter set expectations on the reliability of estimates of elastic properties from AVA inversion. Case studies for a soft gas sand and a hard wet sand are provided.
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Defining Reservoir Compartments and Baffles: A Case Study in Deepwater Sabah, Malaysia
Authors J. Jong, M.A. Khamis, S.M. Barker, R.C. Shoup and W.M.Z. W EmbongSummaryOne of the key challenges in deepwater exploration is the prediction of reservoir geometries. Basin floor fans, deepwater channel systems and crevasse splays, ponded turbidites and MTDs are the main depositional geometries that can result in reservoir compartmentalization and baffling in a shale-dominated environment. This study aims to define and understand the various reservoir compartments from a deepwater Sabah case study, applying both structural and stratigraphic approaches over the Kinarut to Pink stratigraphic intervals. The application of sequence-stratigraphic interpretation techniques in conjunction with sedimentary-processes enables geoscientists to unravel the complex deepwater depositional architecture. The integration of multiple G&G data is employed to define the deepwater reservoir setting and possible sand fairways. These methods include structural and sedimentary seismic analysis, seismic attribute studies and spectral decomposition analysis. The interpreted results are then related to regional deformation episodes, with a pre-kinematic phase and a post-kinematic phase observed. Their impact and controls on the sedimentation styles and the resultant variations in reservoir geometries and compartmentalization are then discussed.
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Influence of Frequency and Training Models on Physics-Guided Velocity Model Building
Authors S. Dhanapal, H. Rusmanugroho, M.D.D. Muhammed, J. Sun and J. LiSummaryVelocity model building (VMB) is subsequently used to provide subsurface velocity model for workflows such as seismic imaging and interpretation. As two widely used velocity model building techniques, ray-based tomographic approaches are not very effective in complex geological settings; and Full waveform inversion (FWI) approaches are computationally extensive and sensitive to initial model. The physics-guided deep learning based velocity model building, that involves deterministic, physics-based modelling and data-driven deep learning components, is designed to capture the subsurface salt body shapes and locations, with a small amount of training models. In this work, we further discuss the influence of dominant frequency and training models on the velocity prediction by using H-PGNN method. Our results show that, the higher the dominant frequency, the more accurate the prediction accuracy of the salt body shapes and background information. For more complicated velocity models and real datasets, simple synthetic training models are not capable of capturing the salt body shapes, nor the background information. A more practical synthetic training set with much more smoothed background layered structures is more suitable to predict complicated models.
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A Review of Digital Transformation Initiatives for Real-Time Formation Evaluation
Authors K. Katterbauer, A. Al Shehri and A. YousifSummaryWe present a thorough overview of the state-of-the-art developments of artificial intelligence and automation, including robotics, in the area of formation evaluation, well logging and reservoir monitoring. The 4IR is and will be a key component in the development of new technologies in these domains and more broadly in upstream oil operations. While there are substantial challenges that need to be overcome in the near future, there is also tremendous potential with the availability of an increased number of interconnected sensing devices for real-time monitoring and interventions [ 25 ]. The 4IR trend is clear and unrestrainable also in Formation Evaluation: automation of measurements, interpretation, interventions and decision making, with minimal human intervention; as well as extensive use of artificial intelligence to support data analytics and interpretation in a framework of indirect measurements, complex characterization, data scarcity and ill-posed problems.
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We Think we're in Control, but are we? A Case Study from Offshore Sarawak-East Malaysia
Authors S. Nazari, P.A. Restrepo-Pace, C. Lee and H.'. Ahmad MunifSummaryStructural restoration and structural forward modelling of 2D cross sections presented here are used to provide structural validation and insights into the kinematic evolution of a hydrocarbon field offshore Sarawak. Structural restoration is the primary workflow used for interpretation validation. Structural forward modelling, on the other hand, provides holistic kinematic review as it constrains deeper fault shape trends. During cross section balancing fault throw, horizon cutoffs and seismic character across faults is checked. The datasets are loaded in two different structural platforms, applying similar methodology in order to investigate how their algorithms operate in an effort to establish more efficient ways to conduct routine modelling. Software A & Software B perform restoration primarily using the block restoration, vertical slip and flexural slip as the parameters. Reference horizon is used and faults slips are removed in order to restore interpreted surfaces and seismic ( Nunns, 1991 ). Due to the uncertainty of deeper fault geometry (poor imaging), structural modelling is used to constraint fault shape. We have now conducted restoration for interpreted seismic sections and forward modelling for fault trend trajectory for Sarawak offshore. Thus, comparison between the restoration results and forward modelling using two different software to narrow down the uncertainty.
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Seismic Characterization of Carbonate Flank Deposits Delineating Upside Potential : A Case Study in Central Luconia
Authors H. Ismail, R.S. Djumeno, A.H. Abd Latiff and N.A. AzmanSummaryCarbonate Flank deposits considered as one of the emerging hydrocarbons play within the proven plays in Central Luconia Sarawak. The potential of hydrocarbon occurrences within this play has been proven by one of the producing fields. Seismic characterization and mapping techniques utilizing multi attributes extractions and well data analysis will aid in delineating the Flank deposits features and connectivity. Detail seismic evaluation of the untapped resources within the carbonate flank deposits is expected to provide good input to assist volume estimation within Central Luconia aimed for hydrocarbon monetization and future resource addition.
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