India's Hydrocarbon Outlook – 2022-2023

67 DGH: 3 DECADES OF UNLOCKING INDIA'S HYDROCARBON POTENTIAL to Recent sediments, mainly deposited by the Ganga-Brahmaputra river system. The hydrocarbon accumulations often indicate charging from in-situ shallower biogenic source sequences. The establishment of thermogenic plays (Mio-Pliocene) in recent discoveries in Bengal onland point to potential deep-seated source rocks, that can also charge deeper plays. Prospectivity The Bengal-Purnea basin has a total conventional hydrocarbon inplace of 541 MMTOE, which is mostly undiscovered and potential for intense exploration. The basin has been assessed earlier during 1995- 96 study along with 14 other basins. During 2017 Hydrocarbon Resource Assessment Study, 3D PSM approach has been used due to availability of adequate datasets. During both the terms, potential of conventional hydrocarbons was assessed. The 2017 resource reassessment study has incorporated 70,550 LKM of 2D seismic data, 13,118 SKM of 3D seismic data, 83 drilled well information. Data are scanty to delineate and characterize the deeper plays. Gravity, 2D seismic, well data and reports are good while magnetic, geochemical and 3D data are fair. Reliabilityof results is good. Gondwana sequence of KG basin has been used as analogue. 3D PSM and Trap Density method have been used to assess hydrocarbon resources due to fair-to- good quality 2D/3D seismic data along with many wells. Seismic quality is very challenging to identify channels in deeper plays. Hinge zone of Bengal basin can be future exploration thrust. More data acquisition from seismic and wells is recommended for characterising channel facies. The play-level undiscovered (risked) conventional hydrocarbon inplace for Onshore area is tabulated below: The play-level undiscovered (risked) hydrocarbon inplace for Offshore area is tabulated below: The play-level undiscovered (risked) conventional hydrocarbon inplace for Purnea area is tabulated below: The onland part of the sub-basin is spread into the state(s) of Bihar, West Bengal. The onland part of the sub-basin is spread into the state(s) of Odisha, West Bengal. 35 MMTOE 7 MMTOE 35 MMTOE 51 MMTOE 3 MMTOE 204 MMTOE 46 MMTOE 6 MMTOE 41 MMTOE 5 MMTOE Cenozoic Pliocene: Cenozoic Pliocene: Paleozoic Permian (Late Raniganj): Cenozoic Miocene (Middle): Cenozoic Oligocene: Paleozoic Permian (Early Karharbari): Cenozoic Paleocene: Mesozoic Triassic (Upper Gondwana): Cenozoic Miocene (Upper): Cenozoic Miocene: Paleozoic Permian (Early Barakar): Cenozoic Eocene: Mesozoic Cretaceous: Paleozoic Permian (Lower Gondwana): Cenozoic Oligocene: Cenozoic Eocene: 26 MMTOE 40 MMTOE 6 MMTOE 11 MMTOE 14 MMTOE 12 MMTOE