Cretaceous Valley Fill Sandstone of Nandigama Area, Krishna-Godavari Basin, Andhra Pradesh

Cretaceous hydrocarbon reservoirs have been recently found in West Godavari sub-basin of the Krishna-Godavari basin. Nandigama area in the sub-basin has encountered gas - bearing sandstone reservoir. However, subsequent delineation of this gas-bearing sand body has remained an enigma due to lack of a viable geological model.

A study was undertaken to decipher the geometry of the gas-bearing Cretaceous sandstone reservoir and to explore the possibility of hydrocarbon potential of the Nandigama area. The present study has shown that the gas-bearing sandstone straddles the unconformity on top of HGS unit of Raghavapurarn Shale and represents the estuarine valley fill sandstone deposited in Lowstand System Tract (LST). The sandstone reservoirs developed in LST constitute the primary exploratory targets for hydrocarbons in Nandigama area, whereas the sandstone reservoirs deposited in Transgressive System Tract (TST) may come up as an additional exploratory target.