Publications

Central Sumatra Basin is a prolific conventional oil and gas sedimentary basin. It also one of Indonesias biggest unconventional gas resources arising from coalbed methane. Evaluation of coalbed methane plays, prospects, and properties is challenging work. It employs intensive complex computation by considerable diversity and volume of data, and also involves a lot of interpretive analysis and mapping.Because the complexity of coal reservoirs, this paper will be objected to implement new techniques and conduct detail study to reduce uncertainties in this area and lay out a standard workflow for coalbed methane evaluation. These uncertainties are related to reservoir geometry and gas content. In order to minimize these uncertainties, limited available data must be fully utilized. In the study area, coal seams were identified from Korinci and Tualang Formation using a cross-plot from density, gamma ray, sonic, and photoelectric effect logs. Gas content was estimated using the Kim Formula, which is calculated using laboratory proximate analysis data from outcrop samples, and also compared to coal properties derived from well logs analysis. Seismic attributes are generated from 2D seismic data by high resolution inversion and spectral imaging. 2D maps of the average values of theses seismic attributes in thin intervals are turned into pseudo-3D seismic attributes cubes that are used as constraints in reservoir geometry.As a result, fields or areas which do not have 3D seismic could still be modeled in 3D using the available 2D seismic data, assuming a reasonable spacing between the lines. Gas content estimation is more accurate because of honoring well log values at original depth. By using these approaches with the same limited dataset, coal geometry and gas content will be presented with more geological logic.Keywords: coalbed methane, Central Sumatra Basin, seismic inversion, spectral imaging, Kim Formula, coal geometry.