Gas Lift Optimization for a Sudanese Field

Abstract

Gas lift is mainly used to decrease bottom hole flowing pressure resulting from fluid hydrostatic pressure and rapid decrement in reservoir pressure. Available gas amount and compressors capacity are the main limitations to this method, thus optimization in each well is the key for the highest recovery. In this study the problem of allocating limited gas to wells network was addressed, the under-study field suffers from production deferment due to gas injection instability which is 40% of the total field production. A commercial multiphase simulator was used to model the field wells and coupled with the nonlinear weighted incremental gradient equations and simulated several scenarios for gas injection limitation for the total network. the multiphase flow correlations were considered, Begs and Brill was found to be the most accurate correlation for this field. The optimization resulted in several changes in the lift gas for each well; total injection rate incrimination was not affecting the overall oil production rate. Optimum gas injection rate is 7 MMscf\D which is 1 MMscf\D less than the current situation and the oil rate is 8% increased. Some wells cannot benefit from the optimization due to their high water cut and low reservoir pressure. Finally, the economic analysis showed that the 7 MMscf\D optimized injection rate is suitable for this field with 12% income in a daily rate.