Comparison of the Outcrop with Subsurface Geology and Hydrocarbon Prospect of Jaintiapur and Adjacent Areas in Northeastern Bangladesh

Abstract

The presence of hydrocarbons in Bangladesh's eastern region suggests that the Bengal basin has active petroleum systems. The relationship between structural configuration, tectonostratigraphic framework, and hydrocarbon potentiality in the Surma basin, including the Jaintiapur area, has not yet been established despite intensive research in the region. This work combined outcrop geology and subsurface seismic data interpretation along the L13-01, PK-SY-5, and L13-03 lines to evaluate the hydrocarbon prospectivity of Jaintiapur and the surrounding Dupigaon area. Based on sequence stratigraphy in the Sylhet region from outcrop, seismic, and well-log data, the primary three megasequences have been identified. Surma basin covers the northeastern part of the Bengal basin, representing a promising petroleum-bearing basin in southeast Asia. Eleven litho-stratigraphic units can be used to categorize the exposed Tertiary and Quaternary rocks of Jaintiapur and the surroundings. These rock units were deposited in fluvial, deltaic, and shallow marine settings, according to detailed facies investigations. Data from the Sylhet-7, Kailashtila-4, and Jalalabad-1 wells have been used to determine the underlying lithology of the research region. The Dauki Fault System dominates the tectonically complicated province where the Jaintiapur region is located. Intense rock deformation can be seen in the area through folding and faulting. Geological studies of the surface and subsurface reveal that faults run parallel to rivers while transverse faults divide reservoirs. The Petrel software has been used to interpret a total of seven horizons. Based on transverse faults and amplitude anomalies at the PK-SY-5 line that have distinct bright spots, the seismic attribute analysis identifies leads and prospects. It appears that the same gas-bearing sand is present in the Sylhet-7 well and the surrounding area in the Dupigaon based on seismic interpretation, attribute analysis, and lithofacies distribution. The gas sands of the Sylhet-7 well indicate the possibility of gas/oil in the equivalent sedimentary sequence in the Dupigaon structure as this area is located close to and more down-dip towards the kitchen area.