An Efficient Way to Cope with Water Injection Problems of Light Oil Reservoir in BOHAI Oilfield

In light oil reservoirs the wellhead pressure of injected well tends to increase rapidly and conventional measures such as acidification only get a short effective period, which severely restricts the amount of water injected into the oil field. The phenomenon mentioned above is called “Pseudo Blocking” in this work. Once Pseudo Blocking occurs, the oilfield pressure is difficult to maintain and the oil production declines easily. To explore the mechanism of this phenomenon, this work gives a full expression of seepage resistance between injection and production wells through a comprehensive derivation: the seepage resistance is related with the shape of the reservoir and the total fluid mobility. The seepage resistance of different light oil reservoirs is calculated as well as analyzed in the southern part of BOHAI Oilfield. A bunch of type curves which shows the possible occurrence time of Pseudo Blocking is obtained. When Pseudo Blocking occurs, the following measures can be taken: pressure-increasing injection for high burst pressure reservoirs, intra-layer gas generation for reservoirs with low burst pressure or highly fractured, yet gas flooding development can be considered for the ultra-low oil viscosity reservoirs. For commingled reservoirs, priority should be given to the vertical contradiction elimination.