Integration of Electrofacies Analysis and Seismic Inversion for Improved Reservoir Characterization of Early Cretaceous Reservoir Rock, NIM-TAY Block, Lower Indus Basin, Pakistan

Abstract

Hydrocarbons are essential in the current industrialized society because they provide energy. To map and define a hydrocarbon reserve, better subsurface information is needed. This requires analyzing blocks for petroleum plays and structures. In several blocks, Cretaceous Lower Goru Formation has hydrocarbon reservoir proven potential. The NIM-TAY block, with its hydrocarbon-bearing structural traps, requires comprehensive research. To assess hydrocarbon potential and structural favorability, seismic data was analyzed and two horizons and four normal faults were delineated. The structural interpretation shows Graben structure limited by normal faults indicating the studied area's extensional tectonic regime. Petrophysical analysis indicate the presence of gas bearing zone within in the Lower Goru Formation. The value of effective porosity, shale volume and water saturation in this zone varies from 8.63-12.9%, 8.06-16.62%, and 36.84-53.57% respectively. Further four electrofacies i.e. sand, shaly sand, sandy shale, and shale were identified using unsupervised machine learning technique. The spatial distribution of these facies was analyzed with the help of Stochastic inversion. Results clearly indicate that the upper portion of Lower Goru Formation and northwest side of study area mainly contain sand facies. Whereas, the lower portion contain mixed facies. The proposed technique can be applied to delineate the reservoir facies in those areas having same depositional environments