Abstract

The Mumbai High Field, located on India’s western continental shelf, has been a cornerstone of offshore hydrocarbon production for nearly five decades. This study focuses on the underexplored Late Oligocene L-V reservoir, a wedge-out carbonate unit developed unconformably over the Deccan Trap basement. Through integrated interpretation of reprocessed PSTM seismic data, well logs, and petrophysical analysis, a coherent geological model was developed, delineating the reservoir’s geometry, depositional history, and hydrocarbon potential. The L-V unit exhibits significant lateral facies variation, with carbonate-rich sections pinching out over structural highs and more shaledominated sequences toward the flanks. Two hydrocarbon-bearing intervals were identified: an Upper Pay Zone—gas-bearing with a GWC at 1574 m TVDSS—and a deeper Lower Pay Zone—oil-bearing with a GOC at 1620 m TVDSS and LKO at 1683 m TVDSS. Volumetric analysis suggests over 5 million metric tonnes (MMt) of oil and oil-equivalent gas (OOEG) in place across a 20 km² oil-bearing area. Validation of the geological model occurred in 2024 with the successful drilling of Well F, which intersected the L-V reservoir as predicted. This confirms the model’s reliability and highlights the potential of wedge-out carbonate systems in mature offshore fields. The study demonstrates how legacy data, and targeted drilling can unlock new value from historically overlooked intervals.