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WEST AFRICA
Waiting at a bus stop
Brief history of the country
Guinea-Bissau (officially the Republic of Guinea-Bissau) is bordered by Senegal to the north and Guinea to the south and east. The Atlantic Ocean forms its western border.
The region was on the fringes of a number of African kingdoms prior to the arrival of the Mandinka from the north in the 12th century. It became a province of the Mali Empire in 1235 ruled by the commander of Gabu. From 1537, when the Mali Empire declined, Gabu became an independent kingdom, trading slaves with the Portuguese.
Gabu was defeated in 1867 by Fulani Muslims who, in turn, were suppressed by Portugal who had set up set up trading posts on the coast (known as the Slave Coast) in the 16th century. The whole country was finally absorbed into Portuguese Guinea at the end of the 19th century.
With support from communist countries an armed rebellion of the population began in 1956. The rebels took military control over the interior until independence was declared in 1973 and recognised in 1974. Bissau was added to the country's name to prevent confusion with Guinea.
Guinea-Bissau has had a history of political instability since independence and the country is very poor depending mainly on agriculture with fish and nuts as its major exports.
Oil and gas summary
Guinea-Bissau is a generally low-lying country with its highest point at just 300 m. The terrain is mostly low coastal plain with swamps of mangroves rising to forest and savanna in the east. Offshore an extensive carbonate shelf zone eventually dips beneath the Atlantic Ocean.
A large, undeveloped, heavy oil accumulation was identified offshore in 1967 (Dome Flore) in Senegal that overlaps into Guinea-Bissau and now lies in a jointly owned area; the AGC. Exploration has also been conducted onshore to find similar fields. A small oil field, Sinapa, was discovered outside the AGC in 2004 in a salt-related structure.
A few wells have been drilled in deep waters and the country may have prospects analogous to a field discovered in Senegal to the north in 2014 which contains oil bearing Cretaceous basin floor fans and shelf edge to slope clastic deposits. Similar plays have also been tested elsewhere along the West Africa margin.
Onshore, Guinea-Bissau is unlikely to achieve production from the Senegal or Bove basins but there is a possibility for offshore production from shallow or deep waters, but not in the short or medium term, and no reserves has been allocated by Globalshift.
GUINEA-BISSAU
Map and National Flag
West Africa
Capital
Population
Land area (sq kms)
Oil prod (000s b/d)
Gas prod (bcm/yr)
Oil cons (000s b/d)
Gas cons (bcm/yr)
Bissau
1.6 mm
36,125
None
None
3.1
None
Government
The president of Guinea-Bissau is head of state and the prime minister is the head of government. Since 1974, no president has successfully served a full five-year term.
A 100-member unicameral National People's Assembly is elected for a 4-year term.
The AGC Management and Co-operation Agency oversees and administers activity in the joint maritime zone with Senegal.
Empresa Nacional de Pesquisa e Exploração Petrolíferas, E.P. (Petroguin is the NOC, incorporated in 1986, and operating under the supervision of the Ministry of Mines and Natural Resources. Its role is to promote and administer the petroleum resources of Guinea-Bissau and is the state concessionaire.
Geology and History of Exploration
Offshore and the western part of onshore Guinea-Bissau are underlain by the southern part of the Senegal basin known as the Casamance-Bissau sub-basin (in the north the Dakar-Banjul sub-basin).
The Senegal basin - is an Atlantic-type passive margin basin of Middle Jurassic to Recent age which began to form within a Permian to Triassic rift system that developed over an extensive Paleozoic basin during the breakup of North America, Africa and South America. It continued as a passive margin basin after opening of the ocean.
The northern limit of this basin is the Precambrian Reguibate Shield in Morocco, the southern limit is the Bove Basin and the eastern edge is Precambrian rocks of the Mauritanide Mountains, uplifted during the Late Paleozoic Hercynian Orogeny.
Onshore the basin is unproductive and Globalshift believes it probably lacks source rocks and traps. However, offshore the Dome Flore and Dome Gea heavy oil discoveries, shared with Senegal, lie on the shelf edge. They have Late Cretaceous sandstones and Oligocene carbonate reservoirs mostly containing heavy oil. They have never been made commercially viable. The Sinapa discovery further offshore found oil in a Cretaceous sandstone associated with a diapir of Triassic salt.
There may also be potential oil and gas accumulations in deep waters. Drilling in Senegal to the north located petroleum systems associated with Cretaceous basin floor fans and shelf edge to slope clastic deposits. Similar plays have been tested along the West Africa margin. Salt deformation in the deep basin also provides potential traps.
The Bove Basin - lies beneath the Senegal basin along the eastern onshore part of Guinea-Bissau. It is a Palaeozoic basin deposited on the northwestern margin of Gondwana.
The basin contains Cambro-Ordovician sediments dominated by continental deposition followed by a marine transgression from the Early Silurian to the Lower Devonian. Some oil seeps have been reported in Guinea and there may be a source rock interval of Silurian shales corresponding to other areas in North Africa. The nearest wells where these have been drilled are in Senegal.
History - Guinea-Bissau has no history of production but a number of oil discoveries have been made offshore, the largest in an area straddling the boundary with Senegal. AGC was created in 1993 between the governments of the 2 countries to jointly administer this maritime zone between the two countries.
The exploration of the AGC area began in 1958 when it was separately awarded to Total in Senegal and Exxon in Guinea-Bissau. Initial exploration focused on salt diapir-related structural traps and resulted in the discovery of the Dome Flore heavy oil field in 1967 and the Dome Gea heavy oil field in 1971.
ln 1991, Casamance Petroleum took the area and acquired 3D seismic. The licence expired in 1994 and the area was subsequently relicensed to Pecten who, in 1996, drilled a shallow exploration well on the eastern flank of Dome Gea (Baobab-1). This well encountered many levels with oil shows.Two permits for hydrocarbon exploration in the deep water areas (AGC Central and AGC Profon) were awarded in 2001. After seismic surveys one dry well was drilled in AGC Profond in 2011.
In Guinea-Bissau outside the AGC the shallow water Sinapa oil field in Block 2 was discovered in 2004 when Sinapa-2 drilled by Premier Oil intersected an oil column associated with a salt structure. Two appraisal wells were successful but the small size of the accumulation has so far prevented development.
A few wells were drilled in the early 1960s in the onshore part of the basin but all were dry.