Abstract

Ariyalur-Pondicherry sub basin of Cauvery Basin, located on the East Coast of India hosts more than 6000 m. sediments ranging in age from Early Cretaceous to Recent. Sandstone belonging to Bhuvanagiri Formation of CenomanianTuronian in age of Lower Cretaceous System has been proved to be oil/gas bearing. Based on lithological association and biostratgraphic data, Bhuvanagiri Formation has been divided into two sub units viz. Lower Bhuvanagiri (Cenomanian) and Upper Bhuvanagiri Formation (Turonian). Sandstone occurring in Lower Bhuvanagiri Formation is termed as Lower Bhuvanagiri sandstone and that of Upper Bhuvanagiri Formation is named as Upper Bhuvanagiri Sandstone. Bhuvanagiri sandstones having limited aerial extent are distributed in scattered fashion as discrete lobes. Mass transport gravity driven mechanisms, e.g., non-channelized debris flow and sandy slump have been identified as the principal depositional processes for Bhuvanagiri sandstone acting under bathymetry ranging from 150m. to 200m+. Sandstones located especially in the basinal part are highly altered by digenetic processes. However, sands towards the flank of the basin have the better porosity not only because of less overburden effect but also due to generation of secondary porosity by meteoric water flushing. Based on the integrated study, prospective areas have been delineated which could be the future exploration target in this sub-basin.