The deal was done through Essar Exploration & Production, Mauritius as Essar Oil is in the process of consolidating its upstream exploration and production activities, Daily News and Analysis reported.

"This will help build a strong, fully integrated oil company with upstream, refining and downstream marketing activities," a representative said.

The Vietnam block is a shallow water block. The exploration phase is estimated to last five years with an estimated investment of approximately $60 million.

The work program for the block includes geological and geophysical studies, reprocessing of existing seismic data, acquisition, processing and a new seismic study. There are also two exploratory wells planned for the block.

Once completed, Essar Oil will have eight oil and gas blocks and one coal bed methane block.

Essar's E&P portfolio currently includes 11 onshore and three offshore blocks for oil, gas and CBM in India, Madagascar, Mauritius, Myanmar and Nigeria.