ONGC plans to participate in the Sonaref project through its subsidiaries ONGC Videsh Ltd for upstream exploration and Mangalore Refinery and Petrochemicals Ltd for the refinery project.
Sources said the company had in July held talks with Sonangol in London to finalise partners for the project and firm up structure of the partnership.
Sonangol had also invited Hydro, Exxon, Sinopec, Chevron, Energem, Petrosa and the existing group of partners in Block 15, 17 and 18 for the talks.
OVL recently received a communication (from Sonangol) seeking details on updating market studies for the refinery.
It is preparing the queries in association with MRPL, they said. Angola's state-owned Sonangol would hold up to 40 percent interest and is looking for partners to keep minimum of 20 per cent stake.
The project is estimated to cost $3.75 billion and is expected to be completed by 2009-10.