Nemba Field Development: A Phased Approach

Abstract A phased field development program is currently underway for the Nemba Field offshore Cabinda, Angola, This paper provides the current geologic interpretation, a description of the existing/planned development facilities, and the general reservoir management philosophy utilized for Nemba. The benefits resulting from phasing field development at Nemba are discussed. Introduction The Nemba Field is located approximately 60 kilometers offshore Cabinda, Angola in 350-400 feet of water. The field lies within Area B of the Cabinda Concession, and is being developed on behalf of the Cabinda Association (Sonangol, Chevron, Elf and Agip) by Cabinda Gulf Oil Company Limited (CABGOC). A map of the Cabinda Concession is provided in Figure 1. The Nemba reservoir occurs within the Albian-age Pinda Formation. A large gas cap, more prevalent in the northernportion of the field, provides the primary reservoir drive mechanism. It is estimated that the field contains in excess of 3 trillion cubic feet (TCF) of associated and non-associatedgas and I billion barrels of oil and condensate. The field was discovered in October 1990. Following a three well delineation program in the southern portion of the field, a phased field development strategy was initiated in the second half of 1993 which includes primary oil developmentas well as secondary oil recovery by gas injection. The phased development plan includes the following major components:an early production system (EPS) in the central Nemba area that came onstream in January 1996,drilling, production and gas injection facilities in thesouthern portion of the field (ie., South Nemba) scheduled to come onstream in the second quarter of1998,drilling, production and gas injection facilities in thenorthern portion of the field (ie., North Nemba) scheduled to come onstream in 2000, andan infill drilling program from the South Nemba facilities scheduled to begin in 2001. The phased field development strategy has made it possible to effectively manage the development of the Nemba resource from both a subsurface as well as surface perspective by allowing the Operator to:minimize the geologic/production risk associated with a large new discovery,effectively manage capital, drilling and other resources,optimize production facilities based on a continuallyimproving reservoir characterization, andaccelerate the time to first production and initial project revenue. The phased field development strategy takes advantage of continually changing and improving reservoir information. As reservoir characterization progresses, new information is incorporated into field development planning and production facility designs. Phasing field development will allow the Operator to maximize the value of the Nemba resource to both the Cabinda Association and the government of Angola. This is achieved in part by identifying optimum facility designs which minimize development costs while providing appropriate reservoir management flexibility. Field History The current geologic interpretation of the Nemba reservoir is based on delineation and development activities carried out between 1990 and 1996. These activities included; drill stemtesting of appraisal wells, wireline logging, an extensive coring program, 2-D and 3D seismic evaluation, and utilization of production data from the Nemba EPS.