Why some waterfloods fail

A recent survey of waterflood operators indicates that poor sweep efficiency, unusual and unexpected expenses, and equipment malfunctions are responsible for about 90% of all economic waterflood failures. Poor sweep efficiency can be traced to reservoir problems involving permeability variations, fluid properties, fluid distribution, fluid saturations, or fracture systems. The second most frequent reason for economic failure of a flood is improper plugging of oil wells. The remedial work required to repair these wells may require the expenditure of large sums of money not aniticipated when the project was designed. Under-design of injection and/ or producing facilities may result in equipment being unable to handle the increased fluid loads involved. It is noted that unfavorable permeability variation can promote water bypassing and large quantities of oil in place in the reservoir. When the fractured reservoirs are flooded, early water breakthrough can be expected if both injection and producing wells are located along the fracture plane.