India's Hydrocarbon Outlook – 2022-2023

56 DGH: 3 DECADES OF UNLOCKING INDIA'S HYDROCARBON POTENTIAL to form the Deccan Trap over the Mesozoic sediments. The Cenozoic sedimentation marked the beginning of the post rift development of the western continental margin of India. As the Indian plate drifted away from the spreading centre, the continental margin experienced passive subsidence and got differentiated into shelf, slope and basin floor. Tectonic activity in the Tertiary was mild as could be seen from the presence of numerous unconformities. Till the Early-Middle Miocene similar depositional system tracts could be seen repeated during each sea level change. Post Middle Miocene, monotonous shale/clay were deposited over the entire western margin indicating heavy clastic influx resulting in the basinward shift of the shelf-edge to its present position. The Kutch onland basin extends between Allah Bund Fault in the North, Kathiawar Fault in the South and Barmer-Radhanpur Arch in the East. It extends into the offshore with wide shelf platform. Malani Rhyolites, which are exposed in Rajasthan, Nagar-Parkar range in Pakistan, and encountered in the onshore drilled wells at Banni Graben (Banni-2) and Saurashtra Peninsula (Dhanduka-1), have formed the Pre-Cambrian basement and it is even correlated with granitic rocks of Seychelles, indicating a continuity before it got separated from Indian Plate during Late Cretaceous. Stratigraphically, the northern limit of Kutch outcrops is continued beyond Indo-Pakistan border. In the offshore of Kutch and further south, the basin is contiguous with Saurashtra Offshore basin. Middle Miocene and Early Eocene are the main pays and additional hydrocarbons plays are established in Paleocene, Late Cretaceous, and Early Cretaceous in the basin. All the hydrocarbon accumulations are related to mild inversion tectonics involving Mesozoic and Tertiary sections. Prospectivity The Kutch basin has a total hydrocarbon inplace of 508 MMTOE, out of which 71 MMTOE has been discovered and this is now entirely sub- commercial inplace. The remaining, 437 MMTOE, nearly 86% of total inplace is potential to be explored and discovered. The basin has been assessed earlier during 1995- 96 study along with 14 other basins. During 2017 Hydrocarbon Resource Assessment Study, 3D PSM and Aerial Yield have been used. 2D seismic data are reported combined with Saurashtra Basin due to contiguity of datasets. The 2017 resource reassessment study has incorporated 95,576 LKM of 2D seismic data, 68 drilled well information. Data quality is good. Gravity, geochemical, 2D/3D seismic, well data are good, reports are excellent while magnetic data are fair. Reliability of results is good. 3D PSM and Trap Density method have been used to assess hydrocarbon resources due to sufficient data support. Poor sub-basalt imaging is a major deterrent for assessing Mesozoic geology. Mesozoics can be major thrust of exploration. Acquisition of close grid 2D seismic long offset data is recommended, followed by 3D campaigns. The play-level undiscovered (risked) hydrocarbon inplace for Onshore area is tabulated below: The onland part of the sub-basin is spread into the state(s) of Gujarat, Rajasthan. 15 MMTOE 11 MMTOE 7 MMTOE Mesozoic Cretaceous (Early): Mesozoic Jurassic (Late): Mesozoic Jurassic (Upper): Mesozoic Jurassic (Lower): 6 MMTOE