Heritage said it reached an agreement through its Nigerian subsidiary, Shoreline Power Co. Ltd., to acquire a stake in OML 30, a group of eight fields and associated infrastructure in the Niger Delta.
The London-listed energy company said OML 30 is producing, on average, around 35,000 barrels of oil per day.
"The acquisition of OML 30 is transformational for Heritage, providing a material change in production and reserves whilst pursuing our strategy of generating shareholder value," said Tony Buckingham, chief executive officer of Heritage, in a statement.
Heritage estimates that OML 30 has gross proven and probable reserves of more than 700 million barrels of oil and 2.5 trillion cubic feet of natural gas. OML 30's infrastructure includes a section of a regional pipeline that has the capacity to carry 850,000 bpd.
Militants in the Niger Delta have attacked oil and natural gas infrastructure in the past. Around 11,000 villagers from the Bodo community in the Niger Delta filed suit in a London court against Shell this year, saying oil spills in the region devastated the regional fisheries industry.
Buckingham, according to The Guardian newspaper in London, is a former British "mercenary."