Discussion on Cycle Water Injection Effect and Its Influencing Factors

Cyclic waterflooding is a kind of waterflood technique, which can improve the waterflood efficiency in low-permeability and fracture-porosity reservoir by changing periodically injected water volume. This article gives the principle and the applied conditions of cyclic waterflooding, and analyses in detail the factors that affect the effectiveness of cyclic waterflooding. The following conclusions are drawn: the earlier the application of cyclic waterflooding process, the better the effectiveness, but the optimal time should be determined by numerical simulations; the lower the permeability, the longer the cyclic of the process; the less the formation elasticity, the shorter the cycle; the less the pay zone uniformity, the better the effects; the effectiveness will be the best if the capillary force has a proper value. If the ratio of vertical permeability to horizontal one is 0.5, the process effects will be the best; the best cyclic waterflooding effects can be achieved by carrying out nonsymmetrical injection-production process of alternately water injection and oil production.