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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
81 - 100 of 132 results
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Imaging Thrust Belt with Multi-Azimuth FWI and Least Squares Migration
Authors B.Y. Ong, J.H. Tan, S. Maitra, C.C. Lam, N.N.H. Che Soh, C. Onn, N. Huu Nghi, N. Hamza and N.N. Abdul RahmanSummaryWe dive into the application of high frequency multi-azimuth (MAZ) full waveform inversion (FWI) and least-square Q reverse-time migration (LS-QRTM) to address the challenges brought about by the fold-thrust belt system within the offshore deep-water Sabah. The imaging of the main structure of the study area has been challenging due to complex velocity variation, steeply dipping complex geological structure and structural uncertainties below shallow gas bodies.
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Structural Analysis of the Distal Stretches of Rift System: Case study from prolific Pre-salt Campos Basin
Authors H. Wahab, S. Sherkati, Z. A Kadir, A.A. Hashim, M. M Nor, N.Q. Salim, N.A. Razali, S.F. Jabbar and L.W. ChingSummaryDistal stretches of prolific Campos Basin remain poorly understood for crustal evolution and salt deformation, which may have significant impact on the development of effective source rock, reservoir, and hydrocarbon charges. salt thickness variation through time, duration of rifting and heat flow evolution are some of the main uncertainties. So heat flow evolution of those frontier zones, which is crucial for petroleum system modelling is still subject of debate. In this paper we aim to use 3D seismic and well data for 3D structural restoration and paleo heat flow estimation of distal Campos margin.
The study integrates both 2D & 3D structural restoration techniques, a leading edge technological application for structural analysis mainly used to estimate initial salt thickness, update subsidence curves and to estimate heat flow. By doing this, the model successfully incorporates the complex tectonic and paleo-salt movements (halokinesis) in the outboard Campos. The robust thermal model is expected to predict hydrocarbon phases correctly further outboard provided the other petroleum system elements remain consistent.
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Importance of estimating original source potential: A case study in the South China Sea
More LessSummaryTotal organic carbon (TOC) content and hydrocarbon index (HI) are one of the basic parameters to evaluate source potential. However, the measured values of TOC and HI from the samples have been decreased from their original one differentially to the buried depth as the rock samples from a source rock have gone through different thermal maturity stages. Hence, it is required to get an accurate estimation of the original total organic carbon (TOCo) content and original hydrogen index (HIo) from measured values of thermally mature organic matter.
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Improvement on Structural Mapping in Tinjar Province through Air-FTG
Authors S.N.F. Jamaludin, C. Murphy and R. KittrellSummaryWith the advancement in data acquisition and processing, the interpretation of data in the complex geological area of Tinjar Province is now being re-look. Variations in the wavelength of the gravity data acquired via this method allow structural interpretation at shallow and intermediate ranges to be compared with the existing work on SAR analysis. Prominent NE-SW orientation Meanwhile, the aeromagnetic data acquired along with the Air-FTG provides understanding for deeper section of subsurface. The aeromagnetic data focus on the top of basement, which deduce E–W orientation. This E–W orientation reflects the potential basement orientation underneath northern Sarawak. Similar orientation of E–W structures are commonly found in central Sarawak representing igneous or metamorphic origin, which better captured by the magnetic signals. Apart from useful in locating new or adding to our understanding of the existing hydrocarbon sites in Tinjar Province, airborne gravity and aeromagnetic data are also useful in improving the understanding of regional geology for onshore Sarawak.
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Mapping the Distribution of Reservoir Facies on 3D Seismic Data using Convolutional Neural Networks
Authors H. Pratama, A. Latiff, D. Markus and E. PurnomoSummaryUnderstanding the distribution of facies in a reservoir is important for reservoir characterization and can be used to aid in identifying the locations of hydrocarbons. However, due to the complexity of the earth’s subsurface, predicting the facies distribution information is often a very challenging task. Recently, the growth of computing power has enabled the application of Machine Learning models in service of studying many geoscience challenges, including the classification of facies using seismic data. Although, many previous studies have mainly relied on the use of multiple seismic attributes to build and train the model, in this work, we develop a Convolutional Neural Network (CNN) model using a U-Net architecture that can accurately map the facies distribution using only the original 3D Post-Stack seismic data. The approach was applied on a reservoir from a real oil field in the Malay Basin. We have improved the model using transfer learning that allows us to use learned parameters from a pre-trained model. The results obtained from the U-Net CNN model provide an accurate and realistic facies distribution compared with the true facies distributions. The model obtained 94% of accuracy for the training dataset and 89% of accuracy for the validation dataset.
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Improving Stratigraphic Interpretation of Sarawak Wells Using Detrital Zircon Geochronology
More LessSummaryThe interpretation and correlation of Cycles I and II in Teres-6 and Tenggiri Marine-1 is difficult due to the wells’ poor biostratigraphic data and seismic quality. Many attempts to re-evaluate them using the same old, inadequate dataset were inconclusive. Therefore, this study used the under-utilised drill cuttings for detrital heavy minerals study, particularly zircon, that aims to resolve the stratigraphic uncertainty of the wells. The result reveals an interesting finding, especially in the characterisation of Cycle I and Cycle II defined by detrital zircon U-Pb ages. Hence, a new stratigraphic revision is proposed, which re-assigns the reported Cycle I section to Cycle II based on the age-provenance signature of the Phanerozoic imprint (i.e., Permo-Triassic, Jurassic and Cretaceous age population). It also updates the regional palaeodepositional model of Cycle II, interpreting that Teres-6 and Tenggiri Marine-1 were part of a large and connected drainage system sourced from the Kuching-Rajang Range.
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Source, Origin of H2S in Central Luconia, Sarawak Offshore. How much do we know?
Authors N.A.A. A Hamid, A.T.P. Panting, S. Nayak, J. M Shah, W.A. Wan Zakaria, R. Masoudi, M. Dubille, I. Kowalewski, J. Hoesni, M.S. Razak and A. AznanSummaryThis paper presents an integrated approach to understand the potential source and prediction of H2S (undrilled prospects) in Central Luconia through an integrated subsurface modelling workflow. Possible sources for H2S and related subsurface processes leading to H2S accumulation is discussed.
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Geochemical Data Characterization and Spatialization for Petroleum System Analysis-An Example from Offshore North Gabon Basin, Africa
Authors N.S. Mohd Pauzi, R. Das and A.K. UpadhyaySummarySpatialization of multiple geochemical variables is a strong and well-established method to investigate, analyze variations of source potential, hydrocarbon fluid types, and source organofacies through time and space in a petroleum system. In our findings, the Post Salt Petroleum System of offshore North Gabon Basin of Africa is characterized by 4 key source-stratigraphic intervals: Albian, Ceno-Turonian and Coniacian-Santonian and Upper Cretaceous that can be correlated with OAE. Two dominant fluid families associated with organofacies classes B and C (Pepper & Corvi, 1998) were identified from multiple key biomarker ratios and cross plots along with tricyclics and hopane profiles within post salt reservoir system. The work summarily helps to recognize and focus on the desired play and petroleum system elements for further opportunity evaluation and petroleum system modelling.
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Combining Automatic Carbonate Detection with Dynamic Matching FWI to Improve Imaging of Jurassic Reservoirs, Timor-Leste
Authors D. Cavalin, D. Mondal, J. Twigg, A. MacDonald, S. Stokes, J. Rogers, S. Notiyal and N. HandSummaryIn shallow water environments where usable offsets are limited, Full Waveform Inversion (FWI) has become a tool-of-choice to generate high-resolution velocity updates. Traditional approaches such as refraction and reflection traveltime tomography can struggle with capturing sharp lateral and vertical velocity variations responsible for structural distortions deeper in the section. Classical implementation of FWI works at its best when very low frequencies and long offsets are recorded. This allows the inversion scheme to start from a smooth initial velocity model. However, the absence of quality low frequencies below 4 Hz and offsets limited to 6000 m in this project meant that the initial model built from legacy stacking velocities had to be improved prior to running FWI.
We first demonstrate a methodology to automatically detect the top of the shallow carbonate platforms and pinnacle reefs present near the seabed. The small-scale velocity variations added to the starting model bring immediate structural improvement down to the reservoir level and enable FWI to start at a higher frequency band. Alternating between passes of FWI and conventional reflection tomography leads to an updated velocity model conforming to the complex geology. The resulting depth migration enables better fault positioning and mapping of key reservoir horizons.
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Exploration Potential of NW Borneo – Latest Regional MultiClient 3D Opens New Petroleum Plays
Authors T. Choi, J. Beenfeldt, E. Mueller and A. VartanSummaryThe Sabah Basin is situated in offshore NW Borneo and is filled principally with marine Tertiary strata typically more than 8km thick. The basin received major sediment input from the Baram Delta and the now abandoned Champion and Meligan deltas and is a prolific hydrocarbon province extending throughout NW Borneo. Gravity loading and thin skinned deformation has resulted in a fold and thrust belt in the inboard area. Loading was initiated near the shelf in the mid-Miocene, which then propagated north-westward in the Pleistocene. The fold and thrust belt, which hosts turbidite reservoirs within anticlinal structures, has been the major focus for E&P oil companies and represents the most successful hydrocarbon play type in the basin to date. The newly acquired dataset has enabled detailed seismic mapping of the basin fill which has historically been a challenge to image below the regional unconformity (MMU). Furthermore, QI/AVO workflows applied to the broadband data of the fold and thrust belt show that the reservoirs trapped in the low side of the folds, present a low Vp/Vs response, similar to that of nearby discovered fields. These additional stratigraphic trap anomalies occur widespread throughout the Sabah fold and thrust belt.
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Unbiased Prospects Assessment and Portfolio Management with Machine Learning
By F. SchneiderSummaryThis work has made it possible to develop a method and a tool using outranking and machine learning techniques for the evaluation of plays and the unbiased ranking of prospects. The methodology is based on the generation of two indices: The PPI (Play Preference Index) and the OPI (Opportunity Preference Index).
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Partnering Geological Concepts with Seismic Imaging Velocity and its Impact to Quantitative Interpretation Results
Authors C.L. Lai, M. Choo, A. Fahmi Abdullah and S. RongheSummaryThis paper is to demonstrate the importance of geology and its impact on seismic imaging and QI study. By comparing the result from the previous against current seismic processing; PSTM vs QPreSDM, there is quite a big improvement on the 3D seismic data and QI results. During the exploration phase, limited geological information was available, hence in the PSTM processing, no geological input was incorporated. In the most recent QPreSDM processing, geological information was incorporated as more geological information was obtained from drilling the exploration well. The study shows result optimization can be achieved even with the subtle variation.
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Seismic Polarity-Based Sequences to Enhance Seismic Imaging of Carbonate Depositional Environments via the Application of Attributes
Authors R. Rosli, N.A. Zakaria, M.H. Baharuddin and S.S. Abd RahmanSummaryCarbonate rocks although it is prolific are known to be challenging to characterise on seismic data due to its heterogeneity and unique sedimentologic. However, increased knowledge of carbonate deposits and their petrophysical parameters, and higher quality geophysical tools now permit a better understanding of carbonate rocks using seismic images.
This study was carried out to illustrate the advantage of seismic attribute analysis on the high-resolution seismic sequences in imaging carbonate depositional environments. The workflow of imaging carbonate using attributes has been applied on carbonate platform in Central Luconia, offshore Sarawak. Amplitude-based seismic attributes and spectral decomposition (CWT and matching pursuit) were used to inferred the depositional environments. Result shows that spectral decomposition produced better image compared to amplitude-based seismic attribute.
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Well Site Gas for Reservoir Evaluation
Authors J. Moore, T. Dodd, E. Michael and L. JonesSummaryOur presentation discusses the applications of well site gas to reservoir evaluation. It is an under used dataset and opportunities exist to improve how this data is utilised both in future wells and in the large datasets that are available. In the presentation we review this data type, discuss data processing and corrections. We then describe how well site gas data can be used to determine pay and phase in a well. Examples from the Northwest Shelf of Australia are used to demonstrate the work flow.
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Integration of Production Data and Modelling Inventory for 3D Static Model Stratigraphic Framework in Brownfield Development
SummaryPost production data for stratigraphic trap of brown field infers vertical and lateral connectivity in a previously compartmentalized areas. Pressure plot, water cut trend and salinity data concludes that area of unintended multiple water injections received such pressure supports which pose threats to RMP, infill opportunities and production attainability by reducing well life. History matching and AI-driven modelling also supports connectivity throughout the reservoirs. An integrated static model is required to understand the connectivity by building a robust structural vertical and lateral framework, while incorporating detailed stratigraphic concept for baffle and fluid pathway through seismic and geological depositional concept. The static model should no longer be limited to pre-production geological concept but extend into production insights during geological modelling to facilitate dynamic simulation.
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FWI Imaging: Achieving AVA Reflectivity Faster than the Conventional Workflow
Authors J. McLeman, T. Rayment, K. Dancer and T. BurgessSummaryMany seismic processing and imaging workflows have been developed over the years to attenuate aspects of the recorded wavefield which cannot be properly mapped into the image domain through conventional migration algorithms. These workflows, including techniques such as deghosting, designature, and demultiple, have become extensive and time-consuming to execute due to the linear-like fashion they must be applied. Each stage in the workflow must undergo a range of parameter testing with success judged on a subjective basis. We present the application of a novel multi-parameter full-waveform inversion (FWI) imaging technique as an alternative to the conventional workflow. It uses the raw field data to simultaneously perform model building and least squares imaging with all the recorded reflection wavefield. This approach uses the primaries, multiples, and ghosts to generate standard model parameters (like velocity and anisotropy) and high-resolution true amplitude AVA reflectivity images fit for structural and amplitude analysis faster than the conventional workflow. In this paper, we compare the FWI derived reflectivity-with-angle outputs to that of a standard Kirchhoff preSDM workflow to highlight the suitability of FWI imaging to directly supersede the conventional workflows.
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Automated Denoising of Seismic Horizon Interpretations using a Convolutional Neural Network
Authors L. Souche, L. Marcelin and W. GuistelSummaryAcquisition, imaging and interpretation errors may impact the quality and accuracy of structural maps built from seismic data - yielding maps which should not be used directly for model building purposes. Nevertheless, such maps are ubiquitous in legacy datasets and it is often not practical to go back to the source seismic data for fixing the original issues. A common practice in the industry has therefore been to use naïve smoothing strategies, such as Gaussian filtering, for minimizing the impact of geophysical noise. This approach, however, tends to eliminate useful information while retaining some of the artifacts. Better filtering techniques, which rely on geostatistical methods, either require human expertise and interpretation or additional input data, which limits their applicability.
In this paper, we present an automated methodology based on Artificial Intelligence for filtering geophysical noise from faulted structural surfaces. It is composed of a stochastic generator for creating synthetic clean and noisy training data, of a polynomial trend estimator, able to handle fault surfaces, and of a Convolutional Neural Networks similar to the ones used for de-noising digital photographs. We show that it can outperform geostatistical approaches while requiring no expertise or parameterization.
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Applying Reservoir Filling Techniques to the CO2 Storage Modelling Challenge
By G. WilliamsSummaryTraditional reservoir simulation methods have proven challenging in matching known CO2 distribution in subsurface CO2 storage sites. This paper demonstrates how reservoir filling techniques using invasion percolation can be applied to modelling plume migration and better history match known CO2 distribution, and also be used to better predict CO2 migration in potential sites to better understand capacity and containment potential. Examples are shown from the Sleipner storage site in Norway and the In Salah storage site in Algeria to demonstrate how this approach can be applied to different subsurface challenges.
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Application of Machine Learning Technologies on Unstructured Data for Sustainable Exploration Activities – Brazil Pre-salt
Authors T. Looi, F. Baillard, N.M. Hernandez, M.H. Minhat, T.S. Tuan Abd Rashid and M.D.M. RamlanSummaryDuring the exploration activities, one way to obtain the geoscience insights is to interpret the basin regional trends and identify the anomalies. Regional information can be analysed through the vast amount of unstructured data accumulated over the years of exploration. This paper demonstrates a data driven strategy implementing the latest advancement of Machine Learning (ML) and Analytics applied on the massive amount of unstructured data. A case study is performed using the data driven strategy on pre-salt carbonates prospects of Campos and Santos basins in Brazil. This paper has shown by adopting the ML/AI technologies, geoscientists can effectively analyse a massive amount of unstructured data and to gain knowledgeable insights of the regional trends and anomalies for crucial parameters. This is vital to minimize the risk of exploration and promote sustainable development.
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Managing Top of Carbonate Uncertainties via Real-Time Geological Operations Interventions in Extended Reach Drilling Well
Authors F. Yusoff, M.K.A. Mohd Bukhari, N.A. Razali and M.T. ElshafeiSummaryThe paper discusses a key part of subsurface risk management that is often overlooked, especially in carbonate field development - mitigating the impact of uncertainties in Top of Carbonate (TOC). The well, located in a highly prolific gas-bearing carbonate platform was planned as Extended-Reach-Drilling (ERD) well. It was planned to penetrate TOC at the less explored area of the field which then raises two key uncertainties on depth of TOC, and drilling issues at the top of TOC. The actual TOC was observed to be 166 m MD (23.4 m Total Vertical Depth) deeper than prognosis. Real-time interventions were then required to ensure well objectives and ultimately overall production targets are met. In the case that the trajectory was not revised during drilling, the target might have been missed altogether. The agility to change the trajectory in real-time and holistic approaches critically mitigated these challenges. The well was completed with the required open-hole-length (OHL) with maximum stand-off distance from GWC and ultimately delivering production in a relatively unexplored area within the field. The critical decision in real-time ensured the well success as part of subsurface risk management from geological operations standpoint.
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