Countries in southern Africa are opening relatively unexplored regions for licensing to foreign firms.
That was evident this month as energy ministers and senior officials from Zaire, Senegal, Ethiopia, and Equatorial Guinea outlined exploration prospects during the sub-Saharan Oil & Minerals Conference in Johannesburg.
Zaire
Mpetshi Ilonga, Zaire's minister of energy, said his country is optimistic about oil potential in its three sedimentary basins, which cover about half of Zaire.
His government is trying to attract major companies for exploration and production. The government has been collecting data on prospectivity through state firm Petrozaire.
Zaire's coastal basin covers 6,000 sq km, of which 1,000 sq km are offshore. Exploration of this basin began in 1956, with discoveries onshore and offshore placed on production by Petrozaire in the 1970s.
All of Zaire's crude oil is exported because it is comparatively heavy and thus unsuitable for the country's unsophisticated refinery. Imported oil from the Middle East serves as refinery feedstock.
The Tanganyika basin's graben play also has yielded discoveries. Ilonga said government is eager to persuade international participants to explore further and develop finds in this region.
Zaire's Central basin has been explored with aerial and gravimetric surveys during the last 10 years. The government plans to split the area into blocks to offer to oil companies.
"Here we have proven these are rocks that could have generated hydrocarbons," Ilonga said. "The potential of the Central basin requires us to create concessions for oil companies."
Ilonga said Chevron Corp., Mobil Corp., Royal Dutch/Shell, Elf Aqui- taine SA and Agip SpA are among majors working and considering projects in Zaire.
Senegal
Magued Diouf, Senegal's minister of energy, mines, and industry, said his government is updating its mining and petroleum codes as a prelude to courting international companies.
Senegal's Coastal basin features a mid-Jurassic play, while to the south is an offshore region said to be similar to the Gulf of Mexico. The Eastern basin is characterized by pre-Cambrian metamorphic rocks.
Diouf said the first indications of Senegal's oil potential surfaced in 1917, but it was not until the 1950s that exploration began. That led to oil and gas strikes in Southeast Senegal, about 50 km from Dakar.
State firm Petrosen is looking for partners for frontier exploration. Government has created 16 license blocks, seven onshore and nine offshore.
Diouf said the onshore area is a Paleozoic play, while the offshore blocks feature Mesozoic structures.
The onshore area has been lightly explored. An 80,000 sq km area has so far been probed by nine wells and 5,000 line km of seismic data.
The offshore area also is lightly explored. Seismic data are old, and 14 wells to date have penetrated no deeper than 2,500 m below the seabed.
Senegal is offering two exploration approaches to foreign firms.
For northernmost onshore concessions and offshore blocks, government hopes to attract partners to acquire new seismic data. For other "less risky" zones onshore, government is looking for partners to drill four wells targeting separate structures identified by seismic data collected in 1995-96.
Ethiopia
Abiy Hunegnaw, head of petroleum operations for Ethiopia's Ministry of Mines & Energy, pointed out that his country's hydrocarbons exploration history goes back 40 years, although no production had occurred.
About 27,000 line km of seismic data have been acquired and 34 wells drilled. One discovery in the Ogaden basin holds estimated reserves of 68 billion cu m of gas, plus condensate, and is being readied for development.
First phase development is to involve production of liquids for sale to local markets, with gas being reinjected. Second phase production will recover gas for pipeline supply to nearby cities.
Government is offering exploration acreage in Ethiopia's Ogaden and Blue Nile basins. On offer are 14 blocks centered around the gas/condensate discovery.
Most available data, raw and processed, involves the Ogaden Basin, where a seismic survey was completed in 1995.
To the north, in the Blue Nile basin of Ethiopia's central highlands, aeromagnetic and gravimetric data are said to show possible source and reservoir rocks similar to those in the Ogaden basin.
Hunegnaw said, "Oil seepages have been seen here, but there has not been much exploration to date. This is really a virgin area being promoted."
Farther north and even less explored, Hunegnaw said, surveys indicate potential source rocks in the Medele basin.
Under a 1994 production sharing law, contractors are invited to take 25-85% of concessions. Many terms, including seismic survey and drilling obligations, are open to negotiation.
Equatorial Guinea
Juan Olo Mba Nseng, Equatorial Guinea's minister of mines and energy, reported success with offshore exploration north of Bioko Island.
There, units of Mobil Corp. and UMC Petroleum Corp. are moving to begin production from the country's first commercial oil field, Zafiro (OGJ, June 10, p. 28).
Nseng told delegates government plans to invite onshore exploration by foreign firms. He said, "The basin of the River Muni has hydrocarbons potential larger than that north of Bioko Island, yet only five wells have been drilled."
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