Strategy of a Highly Stratified Reservoir in a Super
Al-Enezi, Hamdah1, David Jackson2 (1)
Kuwait Oil Company,
The Third Sand Lower (3SL) reservoir in the Greater Burgan Field is characterized as a highly interbedded sandstone and shale reservoir. It was deposited in deltaic environment as a result of relative sea level rise, followed by progradation of the sediments. The reservoir quality and continuity are highly variable. The formation resistivities are of the order of 10-20 ohm. Water saturation is moderately high, possibly caused by microporosity. Because of the heterogeneous nature, the 3SL reservoir remains mostly deprived from the pressure support from the underlying Fourth Sand (4S) massive sandstone reservoir, which exhibits a strong water drive. The present case study describes a success story of the development of the 3SL reservoir in a sector of the field where four new completions are on production after a gap of almost a decade.
The process of redevelopment included a detailed remapping of the horizon/fault interpretation utilizing 3D seismic, correlating log character of the wells, and tying stratigraphic descriptions with complex water encroachment. The time series data from wells, including production, workover & re-completion information, were also reviewed and analyzed to understand the fluid movement. The Third Sand Lower (3SL) completions in the past were subjected to high drawdown, suffered from inappropriate completions, and were unable to handle increases in salt or water-cut. To select the best method of redevelopment, various options were considered. Dual completions were used with an objective to promote development of the 3SL reservoir from optimally-derived take points to ensure efficient sweep of the remaining reserves (lower completion), while at the same time being able to maintain overall production profiles from the higher, more productive Third Sand Middle (3SM) reservoir (upper completion).