Democratic Republic of Congo held its first oil and gas conference this week, seeking to boost investment in a sector dwarfed by huge amounts of money pouring into the country's mining industry.
Congo began exploring for oil in the 1960s and started offshore production in 1975, reaching a peak of 27,000 barrels per day in 1984. Onshore production began in 1980, peaking in 1986 with eight fields in production.
In 2007, the former Zaire produced roughly 25,000 barrels of oil per day. Here are some facts about companies involved:
Production is dominated by Perenco, a European independent exploration and production company, which bought Muanda International Oil Company (MIOC) from Chevron in 2004.
Perenco operates four concessions, both onshore and offshore, in the southwest Bas-Congo province, which is sandwiched between neighbouring Angola and Republic of Congo.
Perenco's partners in Congo are Teikoku Oil Co. Ltd., part of Japan's biggest oil and gas exploration company INPEX, and ODS. Perenco said 2007 production was about 25,000 barrels per day.
Lake Albert -- Blocks 1 and 2
Tullow Oil signed a production sharing agreement with the government in July 2006 for a 48.5 percent operating interest in Blocks 1 and 2 on the Congolese side of the Lake Albert Basin, which sits in the northwest of the country, on the border with Uganda.
Its partners in this deal are London-listed Heritage Oil with 39.5 percent and COHYDRO, the Congolese state oil company, with 12 percent.
Tullow hopes to combine its Congolese operation with its set up in Uganda, where it has successfully drilled for oil, believes it could be sitting on about 2 billion barrels of oil and is due to start producing next year.
Before Tullow could secure a presidential decree confirming the concessions, Congo's oil minister revoked the deal on Block I and has awarded it to a rival consortium.
The rival consortium includes South Africa's state oil company PetroSA, H Oil and South African-based Divine Inspiration Group.
Divine Inspiration is a partner in the creation of the South Africa Congo Oil Company (SacOil) which agreed in March to be bought out by Johannesburg-listed SA Mineral Resources Corporation (Samroc).
H Oil's website describes the company as an oil and gas exploration company specialising in Africa and the Balkans that was founded in 1987 by senior members of Glencore.
Lake Albert - Block 5
To the south of blocks 1 and 2, London AIM-listed Dominion Petroleum has signed a production sharing agreement with Soco International (38.25 percent) and COHYDRO (15 percent) to explore block 5, also on the border with Uganda.
Kinshasa and Kampala's relationship has long been strained by clashes over resources. Uganda sent its army into Congo during the wars of the 1990s under the pretext of hunting down rebels but was later accused of exploiting Congo's resources.
The prospect of oil riches fuelled further tensions last year and violence broke out in August and September, in which several Congolese civilians and a British oil worker employed by Heritage were killed in the shooting.
Surestream Petroleum - Chaired by Moustapha Niasse, a former Senegalese prime minister who helped negotiate Congo's peace deal, Surestream secured in 2006 a presidential decree on two production sharing agreements with the government in Kinshasa.
The first is for the Ndunda block and the second is for the Yema and the Matamba-Makanzi blocks, all of which are onshore in the southwest of the country.
Brazil's High Resolution Technology and Petroleum is surveying the Cuvette Centrale Basin in central Congo, which it says could hold one of Africa's last giant to supergiant light oil, condensate and gas accumulations.
(Compiled by David Lewis in Dakar; Editing by Alistair Thomson)