Tanzania has been intermittently explored over the last 50 years. Most of the multinational petroleum companies were represented in the area, at one time or another. Significant gas discoveries were made at Songo Songo and Mnazi Bay.

So far a total of 35 exploration and development wells have been drilled. Between l954-2000, 27 new field wildcats (NFW) and eight delineation wells (at Songo Songo) were drilled. Of the 27 exploratory wells, 25 were drilled in the coastal basins and two in the interior rift Rukwa Basin.

The cumulative seismic coverage in public domain is approximately 52,000 km; 28,000 km offshore and 24,000 km onshore, including the interior rift basins. There is an additional 11,000 km of modern non-exclusive geophysical data acquired in the year 1999/2000.

Phase I: 1952-1964
BP and Shell were awarded concessions along the coast, including the large islands of Mafia, Zanzibar and Pemba. Extensive geological work was conducted including the drilling of more than 100 stratigraphic shallow boreholes, gravity, aeromagnetic, and reflection and refraction seismic surveys. A thick sedimentary section was identified and four wildcats were drilled, one each on Zanzibar, Pemba, and Mafia Islands and another onshore in the Mandawa Salt Basin. Although the wells did not encounter significant hydrocarbon shows, they confirmed the presence of seal, reservoir and source rocks combinations in the stratigraphic column.

Phase II: 1969-1979
The State Company, Tanzania Petroleum Development Corporation (TPDC) was established in 1969, and the first Production Sharing Agreement (PSA) was signed with AGIP on former BP/Shell concessions. During this period large regional, on and offshore, seismic surveys were conducted. AGIP, joined by Amoco in 1973, drilled three onshore and two offshore wells, including the significant gas discovery at Songo Songo in l974. The discovery was confirmed by TPDC in 1975-79, through a three well program one of which (SS-2) was a blow-out.

Phase III: 1980-1991
Adoption of The Petroleum (Exploration and Production) Act of l980 and high oil prices, encouraged increased activity. Most of the drilling in Tanzania occurred in this period, including the delineation of the Songo Songo Gas Field and the gas discovery at Mnazi Bay (l982) by AGIP.

TPDC participated in Songo Songo development, drilling two wildcats at Kimbiji and several seismic programs. Increased interest in the interior rifts, partially as a result of Project PROBE, resulted in AMOCO drilling two wells in the Rukwa Rift basin. Shell drilled Dira-1, in Mafia Channel in 1991 and relinguished the license in the same year.

PHASE IV: 1992-1999
At the start of this phase there were no active concessions and little activity except for various studies, and a dedicated effort by the authorities to achieve fiscal and technical agreements for the development of the Songo Songo gas field. TPDC, Tanesco, and Canadian companies, Ocelot and Trans-Canada Pipelines, are actively working on the Songo Songo gas field development, transmission and utilization. Beginning in l995 a number of international companies acquired exploration licenses in the coastal basins. Tanganyika Oil Company, in 1996/97, drilled two wells in the Mandawa Basin. Exploration agreements have been signed with Antrim and Canop, both of Calgary, Canada and Ndovu Resources of Australia. Discussion are underway with Pemba International of Calgary Canada for a PSA over Kimbiji/Ruvu areas. Agreements to develop the Mnazi Bay gas discovery and to build a power generation plant are being negotiated.

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