Gravity Modelling of Mahanadi Basin with Special Reference to Hydrocarbon Exploration

摘要

The Cauvery, Krishna-Godavari (K-G), Mahanadi and Bengal Basins are four major basins on the east coast of India. Of these four, Cauvery and K-G Basins have both on-land and off-shore hydrocarbon deposits. As regards Mahanadi Basin, it has rich coal deposits, but continued efforts by Oil India Ltd to find hydrocarbon in the deltaic region in the depth ranges upto 3000 m have not been fruitful. However, a recent discovery of an offshore gas field 50 km from the mouth of the river Mahanadi has revived the interest among the petroleum geologists and geophysicists. This gas find has motivated us to reinterpret the Bouguer gravity anomalies. The new depth estimates for the sediment thickness by modeling the residual gravity anomaly show it to be much more than earlier calculations, thereby the prospects of the hydrocarbon deposits appear brighter. The deepest region corresponding to the Cuttack gravity low is of the order of 5150 m in contrast to ~3000 m inferred by an earlier study by deep seismic sounding (DSS).