Effects of Directional Permeability Anisotropy on Sweep Efficiency for Five-Spot and Nine-Spot Pattern Flood

Introduction:

Clark and Robert  reported that in 1997, a pilot water flood was initiated in a quiescent part of the reservoir on a 40-acre 5-spot pattern. Four Producers were drilled around a central test water injection well to evaluate the efficacy of water flooding the field. Kuwait Oil Company then initiated an inverted 9-spot pattern water flood to develop the major extent of the field in the most rapid way possible as this entailed the least number of injection lines. The results showed that theoretical sweep efficiency from an inverted 9-spot is inferior to a 5-spot pattern by approximately 50% versus 70%. However, to rapidly restore reservoir energy and initiate water flooding operations, a 9-spot pattern was adopted with the

eventual goal of down spacing the reservoir to a 5-spot pattern.
Conclusively, Clark and Robert  showed that the Kuwait Oil Company was able to optimize water flooding using reservoir management team effective in achieving target reservoir pressures in the major part of the reservoir with the active participation of all team members, subsurface and surface alike. Using this approach, water-cut was flattened with effective decline in wet oil production. According to Moudi  further research on the same field showed that applying the new management approach, individual water flood pattern balance was significantly improved and the field wide Voidage Replacement Ration (VRR) become about 1.2.