Petrophysical evaluation of prospective reservoir zones in Srikail gas field, Bengal basin Bangladesh

Although most of the gas fields in Bangladesh are producing from the same Boka Bil and Bhuban formations, quantitative assessment of reservoir quality is rarely examined. This study aims to characterize the producing and prospective gas bearing zones, study reservoir heterogeneity and quality of Miocene Boka Bil and Bhuban sandstone formations. To achieve such objective, sub-surface core samples, Mud logs and wireline logs of three wells from Srikail gas field in Bangladesh were studied and integrated to perform comprehensive petrophysical evaluation. Three prospective zones: D-Upper, D-Lower and E-Sand have been interpreted. Our results show that shale fraction is a key parameter in determining reservoir quality since it a) causes compartmentalization within gross thickness, and b) reduces permeability at any given porosity. According to the interpretation results, D-Lower has slightly better reservoir properties in terms of shale fraction, porosity, permeability and gas saturation compared to D-Upper. Nevertheless, D-Upper has much thicker net pay thus higher and sustainable production can be achieved from D-Upper. E-Sand has reasonable low shale fraction and good porosity, yet it is water bearing in one of the wells. This is because of its down dip position in the anticline structure, limiting its lateral extend.