Takula Oil Field and the Greater Takula Area, Cabinda, Angola

Summary The Greater Takula Area comprises four offshore fields, Takula, Wamba, Numbi, and Vuko that produce oil predominantly from Upper Cretaceous reservoirs. The fields are located approximately 40 kms west northwest of the Malongo terminal, in Cabinda, Angola in water depths of 50-75 m (150-220') (Figure 1). Current production levels are approximately 177,000 bpd of 34° API oil. The first oil well in the area was drilled in 1971 on a seismically defined horst structure beneath a pervasive salt section that is associated with the opening of the South Atlantic. It flowed 5600 bopd from carbonates of Lower Cretaceous age. It was not until late in 1979, however, that a far more significant hydrocarbon accumulation was found in the Cenomanian sands of the Vermelha Formation. All four fields produce primarily from Vermelha sands deposited on a trend of structures whose genesis was controlled by listric normal faulting and salt movement. The total area of closure for these fields at the Vermelha level is approximately28,000 acres (114 sq km) with a maximum oil column of 440'. To optimize the oil recovery from these fields a staged development project has been ongoing since 1980. It involves initial primary solution gas and/or gas cap expansion drive production, followed by a water flood pressure maintenance program for the major reservoirs. This project has been guided by a detailed reservoir analysis using 3-D seismic, core studies, wire line log analysis, reservoir mapping and simulation matched to production history. To date these fields have produced 300 MMSTB. Exploration History The Cabinda Gulf Oil Company started exploration activities in the then Portuguese administered province of Cabinda in 1954. On November 22, 1957 the original concession covering both onshore and offshore acreage was awarded. By the early seventies the concession had been renegotiated to the current 10,116 sq km with the relinquishment of the onshore and additional acreage offshore out to the 200 m isobaths. The present concess ion is divided into three areas - A, B, and C. All the current production comes from Area A fields. (Figure 1). The first well was drilled offshore in 1966. The discoveries of the Malongo fields followed soon after. These successes focused exploration on the offshore. By today, 14 fields have been discovered and put into product ion, the 1argest of these fields being Takula. Regional Setting Angola lies midway along the length of the South Atlantic rift. The rift developed in late Mesozoic time as plate tectonic activity caused the separation of South America from Africa. The tectonic elements and sedimentary sequences observed along the margins resulted from the evolution of the rift. (e.g., Lehner P. and DeRuiter, P. A. C., 1977). A series of basins developed along the rift. The Cabinda concession is located in the Congo basin which is flanked to the north and south by the Gabon and Cuanza basins, respectively.