India: Returning to the Mumbai High
Despite a mid-year interruption due to Covid-19, ONGC completed BS-17-1 on the Mumbai High as an oil, gas and condensate discovery in late 2020. The discovery, in the West of Bassein Mining Lease, held 100% by ONGC as Operator, is a satellite to the Panna and Mukta fields.
The Panna and Mukta fields, discovered in the 1990s by ONGC and operated over the years by a number of companies including BG Group, produce from several zones within the Eocene Bassein Limestone Formation, which has undergone reservoir enhancement via significant solution porosity, often concentrated along faults. The BS-17-1 discovery, located between the two fields, flowed oil, gas and condensate from three separate zones. Flow rates ranged from 5.5–7 MMscfgd and oil/condensate 272–326 bopd. Although the stratigraphic units for each zone are not reported, the discovery is said to open up the Mukta and Heera Formations for exploration. These Lower Oligocene formations overlie the Bassein Limestone and are considered lateral equivalents of the ‘Alternations’ succession which contains the gas cap at the structurally higher Panna field. Stacked pay in this satellite is an attractive outcome if the fluids are compatible with ongoing production at Panna/Mukta, enabling ready tie-in to extend field life. At the beginning of 2020, the fields were producing about 10,000 bopd and 4 MMscfgd.