Historically, exploration for petroleum in Sudan started in 1950s before the country’s independence. It started when Italian company AGIP acquired a concession area along the Sudanese Red Sea coast in 1959. The extensive exploration efforts of AGIP resulted in no significant commercial discovery of oil.
Due to some of the world oil crisis of the early 1970’s, oil prices rose sharply from $3 per barrel to $12 per barrel, the Sudanese Red Sea coast became the target of many oil companies such as Union Texas, Texas Eastern and Chevron. Chevron won a concession to explore for oil in east of Sudan in several wells. Chevron tested the formation by number of exploratory wells.
Some of them were associated with dry and condensate gas discoveries; on other one was not finished due to technical problems of abnormal pressure and temperature.
In 1974, the Government of the Sudan Republic and Chevron signed exploration Production Sharing Agreement (EPSA) offering Chevron the right to explore an area in the interior of Sudan. This area is as big as 60% of the total area of the sedimentary cover of Sudan.
Through the rest of 1974 and during the end of 1975, aerial photography and land sat have been interpreted. The end of 1975 completed airborne magnetometer and helicopter supported gravity surveys. This work directed the seismic crew to enter the area.
At the end of the year 1976, the well Baraka-1 was drilled in the NW of the Muglad basin complex. Although this well was a dry well (plugged & abandoned) but it was very useful in directing the efforts for the future exploration drilling.
During the first exploration efforts (1975-1980), which concentrated on the Muglad basin, several oil discoveries were made such as: Unity-1, Unity-2 and Abu-Gabra-1 wells.
Following several constructional reigns, Chevron was able to gain another 73200 km2 in the Blue Nile and Baggara basin in 1979. In 1981, nine wildcats were spudded. These include an additional oil discovery in Sharaf-1 in the NW Muglad basin and several appraisal wells in the Unity area.
In the same year the exploration activity was extended to include Talih-1 oil discovery near the Unity field, Adar-1 and Adar-2 in the Melut basin. The exploration work have greatly speeded during 1982, eighteen wells were drilled, in the Muglad and the Blue Nile basins.
Within the year 1983; a total of 24 wells were drilled that included the first and the second oil discoveries in Heglig-1 and Toma-South-1 wells at Heglig field in the Muglad Basin, The activities of Chevron declined sharply.