The Application of Water Alternating Gas Injection to Maximize Oil Recovery in the Niger Delta

Abstract

One of the most significant challenges for extending production life in mature waterflood fields is high water cut. Couple with high reservoir heterogeneity, extensive layering and faulting, these fields often developed irregular flood patterns after decades of production which compounded the challenge of optimizing recovery from these fields. The severity of this problem has been observed in the Niger Delta oil fields, where several matured fields are producing at high water cut after many years of waterflooding. This study aimed to determine the viability of Water Alternating Gas (WAG) injection in comparison with Waterflooding and Gas injection methods for optimum oil recovery of an oil field in Niger Delta. WAG injection had a maximum field oil efficiency (FOE) of 31%, a field oil production total (FOPT) of 4,944 MMSTB, a plateau time of 14 years and a total field water production (FWPT) of 18,356 MMSTB. Waterflooding had a FOE of 23%, a FOPT of 37,466 MMSTB, a plateau time of 9 years and a FWPT of 96,895 MMSTB. Whereas gas injection had an FOE of 15%, a FOPT of 36,063 MMSTB, a plateau time of 3.2 years, and a FWPT of 13,444 MMSTB, respectively. From the comparative analysis of the three recovery methods, WAG injection outperformed both waterflooding and gas injection with the highest FOE of 31% and the longest plateau time of 14 years, respectively.