EAGE/AAPG Workshop on New Discoveries in Mature Basins

Western Luconia, offshore Sarawak is a known gassy area with perceive high CO2 based on discoveries in the area, and this has curbed exploration enthusiasm in the area. To counter the perspective of high risk in exploring this area, a petroleum system modeling was done to ascertain CO2 origin and distribution, with possible hydrocarbon accumulations. This paper aims to investigate whether recent drilled wells, post study, in Western Luconia, match the CO2 trend established in the 2021 basin model. The methodology used in the model includes conducting the possible CO2 origin evaluation, CO2 isotope and fluid PVT (Pressure Volume Temperature) analysis, thermal maturity and CO2 kinetics evaluation, CO2 history matching with existing wells, establishing CO2 maps for different geological cycles, and comparing the recent drilled well results with the established model. This CO2 distribution map has shown to be a powerful tool for predicting CO2 concentration and commerciality. Team can rank their prospect better in this high uncertainty of CO2 content area. Our stakeholder / exploration team will benefit from the CO2 prediction map which helps their decision making from better understanding of the risk and uncertainty involved in the areas.

Globigerina limestone reservoir is a unique clastic carbonate that boasts outstanding porosity of up to 50%, with permeability ranging from 0.1mD to 500mD. Exploration wells encountered heterogenic reservoir quality from excellent (MBH-1) to poor (MBJ-1). To de-risk near-field prospects by avoiding poor reservoir quality, the integration of petrophysical evaluation and advanced seismic analysis was conducted.

The petrophysical evaluation provides reservoir properties such as Vclay, porosity, flow units, permeability, and water saturation to identify sweet-spot intervals. Advanced seismic analysis such as AI, SI, Vp/Vs, and Poisson’s ratio was generated to identify potential reservoirs and predict rock quality inside gas gas-bearing areas. The research is done by utilizing core data, wireline logs, and 3D seismic.

Results from this research, indicate that AI is powerful in identifying hydrocarbon potential areas surrounding the Bangau-3D seismic area. The second result is using a certain range of AI combined with elastic parameters can help to predict rock quality in certain prospects. Finally, the integration of reservoir characterization and advanced seismic analysis can help to distinguish the medium to the best quality of reservoir rock that should be used as a target for the exploration wells.

In 2017, the “MS-1” well was drilled in the West Natuna Basin (WNB) and discovered gas within the shallow section of Muda Formation. The discovery was an important milestone that changed the way shallow gas pockets are seen in the basin, from a potential shallow gas hazard into shallow gas reservoirs. Such a paradigm shift is proven to help discover additional hydrocarbon resources in a new play in a mature basin such as the WNB. Following this success, other explorers within the WNB chased similar play in the region and since then several discoveries have been made. Apart from this newly tested play, WNB holds other overlooked plays where in the study area, the Miocene point bar deposit and the Eocene-Early Oligocene lacustrine-fan delta stratigraphic trap plays are present, situated at close proximity to a wrench fault system. Successful analogues of such plays in other parts of SE Asia region (i.e. South Angsi and Jasmine Fields) suggest the vast remaining potential to explore in the WNB.

The hydrocarbon (HC) phase of an accumulation is the expression of a petroleum system, resulting from a complex interaction of geochemical, geological, and physical aspects. Each of these elements carries its own degree of interdependency, uncertainty, and variation over time. This study will demonstrate how localized variations of depositional settings and magnitudes of structural deformation play altogether a fundamental role in controlling the gas liquid ratio (GLR) charge, hence determining the distribution of HC phase in the reservoirs of the shallow waters of the Sarawak Basin

A recent sedimentology study of the Kenny Hill Formation in Selangor, Malaysia, synthesized with previous work, has given new insight into the depositional facies of the formation and its glaciogenic origin. Coastal Transgressive-regressive cycles correlate to the global eustatic sea-level changes during the Late Paleozoic Ice Age. Submarine fans developed at the base of low-stand canyon incised canyons, opening the possibility of a new play on Sibumasu.

This extended abstract introduces an innovative approach to enhance well logging data interpretation for sustainable near-field exploration in the oil and gas industry. The traditional reliance on real well logs is often hindered by data limitations and confidentiality constraints. To address this challenge, Generative Adversarial Networks (GANs) are leveraged to generate synthetic well logs that closely resemble actual data. The methodology involves data collection, GAN training, and seamless integration of synthetic logs into the interpretation workflow.

The integration of synthetic logs significantly improves reservoir characterization and decision-making in near-field exploration. Two illustrative examples are provided: a flowchart outlining a GAN-based strategy for multidimensional reservoir characterization and a visualization comparing real and synthetic well logging data. These examples highlight the potential of GANs in reservoir modeling.

In conclusion, this approach has the potential to revolutionize well logging data interpretation, offering benefits such as reduced drilling costs, improved exploration success rates, and minimized environmental impact. The presented research draws from Shahbazi et al. (2020) and signifies a significant advancement in near-field exploration practices.

Imaging the subsurface for potential hydrocarbons is pivotal in the industry, primarily utilizing seismic and non-seismic methods (e.g., Gravity, Controlled Source Electromagnetic data). While seismic data offer crucial initial insights into the subsurface, challenges persist due to complexities like intricate fault systems and Shallow Gas, which often hinder the imaging process in Malaysia Basins. A promising solution involves using Ocean Bottom Nodes (OBN) for seismic acquisition, as they effectively handle subsurface complexities, particularly those masked by Shallow Gas. Techniques like Full Waveform Inversion and Reverse Time Migration further enhance imaging in these challenging zones, offering unprecedented clarity. Our study demonstrates that integrating Geology and Geophysics with Petroleum Engineering significantly advances our understanding of the subsurface in longstanding production fields in Malaysia. This multidisciplinary approach has unveiled crucial data regarding reservoir characteristics, fluid contact, Behind Casing Opportunity, and infill opportunities, essential for unlocking the potential of both shallow and deep reservoirs. This integrated method not only informs better decision-making but also ensures quicker project turnaround and maximizes the extraction of remaining hydrocarbons.

Fault mapping using seismic data is an essential step for prospect maturation. Identification of faults specially those subtle enough to be missed is important for better reservoir characterization and well placement. Physical and geometric attributes are the most common techniques for fault mapping. However conventional approaches sometimes have difficulty to illuminate faults in unclear, noisy seismic data and more sophisticated approaches are costly and take time. Seismic quality in outboard campos basin at pre salt section, where continental crust hyper extended and salt thickness and complexity is high sometimes is very challenging ( Figure 1 ). Harsh topography of top pre salt carbonate, which is related to nature of carbonate growth, increase complexity of subtle fault mapping in Sag sequence. Detail fault mapping in Campos ultra deep-water zone has crucial role on safe drilling and well cost optimization. In this study I tweaked conventional fault mapping techniques in deep offshore Campos basin-Brazil to map faults in pre salt section. This approach applied in a prospect that traditional approaches already applied without success.

The BLLA prospect was explored with the objective of assessing the hydrocarbon potential within the Intra-Kais reefal buildup carbonate facies. The well successfully penetrated the reservoir, reaching a total depth of approximately 11,482 feet. Oil was discovered with a net pay thickness of 284.3 feet. The sealing formation was the Klasafet Formation, and the source rock was from both the Sirga Formation and the Klasafet Formation. Geological and operational challenges have had a significant impact on the economic calculations. However, there are other opportunities available that can further enhance the economic prospects.

Malaysia’s geological expanse has both brought incredible success and posed challenges for exploration and resource extraction, often due to the intricate nature of its subsurface. To further enhance these achievements and address the associated challenges, a comprehensive repository of 300,000+ square kilometres of fully processed and interpreted Full Tensor Gravity Gradiometry (FTG) data is available within the region, resulting from data acquisition efforts led by Bell Geospace on behalf of Petronas.

This paper explores the utilization of a novel methodology, Full Tensor Migration (FTM), tailored to extract detailed information from the extensive FTG archive. Initially introduced in 2020 as Source Body Migration and subsequently refined with new techniques in 2023, FTM serves as a rapid, robust inversion technique. Its primary function is to disentangle and extract signal from final processed tensor data, yielding depth interval anomaly maps which are an invaluable resource for exploring within Malaysia’s geological landscape.

The paper underscores the impact of FTM on geological interpretation, with a focus on well-explored Malaysian basins. Through methodological insights and case studies, the authors demonstrate how FTM amplifies signal clarity, heightens depth sensitivity, and streamlines lead generation, providing invaluable support for geological exploration and resource assessment.