Asia Petroleum Geoscience Conference and Exhibition (APGCE) 2024

Magnetic susceptibility is the degree to which a material can be magnetized in an external magnetic field. On volcanic area, magnetic susceptibilities value can be changed with time. When susceptibilities value of volcanic rock is affected with temperature of rock, susceptibilities value can be changed from the eruption of volcanic mountain until the rock cools down quickly. But alteration of rock due to heat factor or material coming up to surface like geothermal manifestation may change the magnetic susceptibility value on the rock. In this research we used 130-point on years “A” and years 2020 (validated on 6 blocks as a zone of interest) to know the effect of magnetic susceptibility changes with temperature changes on reservoir.

Gas while drilling (GWD) data serves as a critical dataset for early detection of hydrocarbon presence in reservoirs. This is achieved through the analysis of total gas measurement and the examination of gas composition, spanning from C1 to C5, to offer an early indication of the formation fluid present, including gas, condensate, and oil. Integration of total gas data, gas composition, cutting observations, and log responses becomes imperative, particularly in wells with complex lithology and within unexpected hydrocarbon-bearing sections. Although the standard practice involves calibrating GWD data against laboratory fluid analysis from downhole fluids to enhance interpretation, the effectiveness of such calibration methods may be compromised due to the distinct acquisition nature of GWD and downhole fluid data. GWD on the other hand is exposed to various uncontrolled environmental and operational conditions, such as flow rate, rate of penetration, changes in mud properties, and extraction efficiency. These factors can to some extent influence the quality of the analyzed gas in the mud logging unit. In this study, we propose an robust gas analysis workflow aimed at refining the interpretation of GWD data, ultimately addressing missed opportunities in identifying hydrocarbon-containing reservoirs.

The utilization of Extended Elastic Impedance (EEI) proves to be a rapid and accessible method for gaining insights into lithology, fairway determination, and reservoir properties, with some indications towards hydrocarbon fluid assessment. However, seismic EEI encounters challenges in terms of uncertainty and reliability, primarily stemming from poor calibration to well data. In the well feasibility study stage, the EEI-transformed property, utilizing raw recorded logs as input, consistently exhibits a wide ranges of Chi angles for different wells. Consequently, the technology is often criticized as unreliable and deemed unsuitable for deployment. This study addresses the critical role of well data pre-conditioning as a prerequisite for successful EEI applications. Four recently acquired wells within close proximity, each equipped with complete elastic logs (density, p-sonic, and s-sonic), are examined in this study. The designated area features water depths ranging from 500 to 1600 meters, predominantly characterized by clastic sediment composed of clay and quartz minerals.

The study focuses on exploring the potential of Pliocene Stage IVF Carbonates as a new play in the underexplored region of Eastern margin of Sabah, Malaysia. Historically, East Sabah spanning from Kudat to Tawau Division, has seen limited exploration, targeting mainly Miocene reservoirs. The discovery of oil staining on Togopi Limestone has since prompted the notion towards targeting younger plays. By leveraging seismic interpretations, integrating well data, outcrops, and updating Stage IVF GDE model, the team was able to narrow down the area for carbonate deposition. Some of these potential carbonate bodies identified have sizeable area upwards of 45 sqkm that may serve as reservoir for future oil and gas exploration opportunities. However, challenges such as sparse seismic coverage and limited data pose obstacles in evaluating quality of these reservoirs, emphasizing the need for further analysis and data acquisition efforts. The study concludes that while Stage IVF Carbonates deposition is widespread in East Sabah, additional analysis is necessary to de-risk the play for potential exploration.

The study focuses on the 3D seismic interpretation of Late Pleistocene offshore Sarawak, investigating its implications for shelf-to-deepwater depositional analogues and sediment routing. The Sunda Shelf, once a broad coastal plain during the Last Glacial Maximum (LGM), offers insights into sedimentary processes through its transition to present-day conditions. NW Borneo serves as a key area for studying sediment supply, routing, and depositional systems. This research aims to reconstruct Late Pleistocene fluvial systems from upstream to downstream regions, utilizing extensive 3D seismic data and shallow boreholes. Notably, the study identifies various depositional elements such as incised valleys, shelf-edge deltas and slope channels, which provide valuable insights into sedimentary analogues and sediment routing. The analysis reveals complex patterns of incised valleys, reflecting changes in morphology and sediment distribution. Palaeogeographic reconstructions also highlight the influence of sea-level fluctuations and tectonic factors on sediment transport pathways. Overall, this study contributes to a deeper understanding of sedimentary processes in shelf-to-deepwater environments and offers important implications for geological interpretations and sedimentary analogues in similar settings.

The Bay of Bengal is one of the world’s last remaining frontier provinces for petroleum exploration. Geological interpretation of new regional 2D seismic data over the Bay of Bengal, offshore Bangladesh offers new insights into the geological history, crustal architecture and petroleum potential of this frontier area. Basin reconstruction and source rock modelling shows the maturity of several source rock intervals for both oil and gas. Interpretation of seismic character allows for a stratigraphic architectural study of the shelf, slope and upper fan. All the elements of a working petroleum system are present and regional data is key to unlocking the full potential of this exciting area.

A comprehensive technical evaluation with geophysical analysis was conducted after the completion of a recent exploration and appraisal drilling campaign to assess the future petroleum potentials in B Field, located in West Luconia Basin, offshore Sarawak.

Understanding of seismic dim zone with the full integration of seismic interpretation, seismic inversion, JiFi and AVO modelling with integration of well data, MDT pressure data, has resulted in an improved understanding of reservoir distribution, and reduced the degree of uncertainty in reservoir connectivity, thus unlocking new petroleum potentials and allowing a more robust development strategy.

This paper focuses on major discoveries, reservoirs of the Upper Cycle V, Sand X and Sand Y, with findings from key wells, namely Well-B2 and Well-B2ST1, using AVO modelling and seismic inversion, with well logs and MDT pressure data integration to better understand the petroleum potential for subsequent development planning.

We have demonstrated that we can achieve consistent simulation synthetic to produce reasonably consistent synthetic surface and DAS VSP strain rate data thorugh series of forward modelling. This gives confidence mat DAS imaging is consistently being modelled, as the ExploreDAS GUI software used to create DAS synthetic data for arbitrary geological model. This is useful to design and strength understanding regarding further data acquisition and processing for both surface and DAS VSP. The simulation system considers DAS response compared to geophone and properly created migrated image with that data. However, through this analysis we identified some differences in terms of capabilities of forward modelling method; migration algorithm, noise limitation, and velocity options. The Synthetic model used P-wave DAS strain rate response mat was able to equalize with geophone in terms of single trace and migrated imaged. Furtherly, in full paperwork model was able to assess gauge length efffect and simulate noise mat might happen in actual DAS acquisition at offshore subsurface features in certain SNR. The major benefits of ExploreDAS simulation software, mat supports quite sufficiendy creating subsurface structures, fiber geometry, and shot locations properly even with very complex geological conditions such as this synthetic Browse basin CO2 storage site.

“In areas with limited well data, evaluating lateral seal at the prospect level becomes challenging. The absence of nearby wells for direct lithology input complicate juxtaposition and shale gouges ratio calibration and interpretation. Our study explores various approaches for prospect lateral seal evaluation, comparing methodologies and post-drill analysis. In conclusion, using supervised QI (Quantitative Interpretation) products in fault seal analysis reduces uncertainties related to stratigraphic facies variation in poorly controlled areas.”

Fluvial deposits are considered as potential for CO2 storage sites; however, it usually presents heterogeneous fluvial architectures which are resulting in both significant and poor storage efficiency. Moreover, the injectivity of CO2 depends on heterogeneity scales and obviously flow barriers strongly impact migration of the CO2 plume. In this paper, a highly depleted gas field, clastic with multiple stacked sands is described as a CO2 storage site ( Figure 1 ). Constraint on seismic quality due to large shallow gas cloud is always the main challenge for reservoir characterization and modelling of the field, even though it is almost the end of field life. Therefore, the key uncertainty of this field is related to the distribution of the fluvial facies, which has a significant impact on containment and storage analysis.

The paper is aimed to present a complete rebuild full model from seabed, including shallow overburden, under burden and depleted reservoirs in a brown field from old reservoir model built in 2005, by maturing its sedimentology model and integrating all geoscience and dynamic data. The model then is history matched and used for injection forecast, thermal simulation and coupled with 3D geomechanical model for CO2 containment integrity study.