Study on methods to improve the flooding capacity of weak alkali ternary compound flooding in transition zone

Abstract

The reservoir in transition zone is characterized by high crude oil viscosity and poor fluidity. Fluidity control requires to improve the injected liquid viscosity, however, due to the poor-developed reservoirs in transition zone, the improvement of injection and production capacity of injected liquid viscosity is affected, and therefore, it is urgent to explore methods to improve the injection and production capacity, and then to improve the development effect. In this paper, using the statistics analysis method, a plan which could match with different types of well group has been formed. For different types of well group, different interval regulation methods are formed by periodic high and low viscosity, high and low speed injection and phased stop injection. Taking injection and production capacity improvement as the core, and combining with the dynamic and static characteristic of reservoirs in transition zone, the optimum plan is formed. Through on-set application, injection pressure of weak alkali ASP flooding in transition zone increased steadily, injection and production capacity decreased slightly, if the pressure could be controlled at about 15%, the injection and production capacity was stable, and the development effect was better than the polymer flooding in transition zone, and it is estimated that the ultimate recovery rate is 1.7 times of that in transition zone. Field practice has proved that the method to improve the injection and production capacity of weak alkali ASP flooding in transition zone has a good popularizing prospect, which provides effective technical reference for the development of other transition zones.