FACIES ASSOCIATIONS AND PALEOENVIRONMENTAL RECONSTRUCTION OF THE RESERVOIR ROCKS OF THE SHAHBAZPUR STRUCTURE,BENGAL BASIN

Reservoir rocks deposited in deltaic system remain challenging for accurate petroleum evaluation and production due to occurrence of alternating productive and nonproductive facies. Nevertheless, understanding such depositional setting is crucial to identify the heterogeneity that affects the fluid flow behavior and storage capacity. Here, we present the results from an integrated study in terms of sedimentology and petrophysical properties of reservoir rocks from the Shahbazpur Structure, Bengal basin. Based on lithologic characteristics and sedimentary structures, the Plio-Pleistocene reservoir rocks of the Shahbazpur structure exhibit eleven lithofacies representing tide-dominating delta depositional setting. The siliciclastic succession of Shahbazpur-2 well represent tidal flat environment which are divided into three subfacies associations: supratidal to intertidal (FA 1a), subtidal (FA 1b) and tidal channel (FA 1c). Facies associations in core-2 succession are arranged in small-scale sedimentary cycles that reflect spatial differences in the response of the depositional system to small scale relative sea level changes. A unique relationship exists between porosities and permeabilities of reservoir rocks that clearly indicate that depositional texture and lithology greatly affect the reservoir property.