Study on the Countermeasures and Mechanism of Balanced Utilization in Multilayer Reservoirs at Ultra-High Water Cut Period

Abstract

After entering the ultra-high water cut stage of multilayer oil reservoirs, the remaining oil is highly dispersed. Due to the continuous development of general water injection, the generation of advantageous channels makes interlayer contradictions more prominent, and the differences in the utilization between different layers are even greater. After the water drive development of multilayer oil reservoirs enters the ultra-high water cut stage, the development effect deteriorates year by year. Layer restructuring is an effective method of improving the water injection development effect and increasing the degree of utilization. In essence, its goal is to achieve balanced utilization for multiple development layers to increase the degree of recovery. This article mainly employs physical simulation experiments combined with reservoir numerical simulation technology to jointly study the effects of different equilibrium production strategies in the ultra-high water cut period of multilayer oil reservoirs and their mechanism of action based on the remaining oil distribution field and streamline field. As a specific implementation, we use large-plate physical simulation to demonstrate the effectiveness of the rotational injection and production strategy, and to supplement the physical simulation experiment with a reservoir numerical simulation model, we analyze the mechanism of different balanced production strategies. The research results for the combination of physical simulation experiments and numerical simulation experiments show that the combined strategy of rotary injection and rotary production is the most effective method for use in multilayer and ultra-high water cut oil reservoirs. The displacement effect of the high-permeability layer is better, and the increase in the recovery degree is relatively large, while the displacement effect of the low-permeability layer is relatively weak. After conventional water drive oil recovery, the remaining oil mainly exists in the edge area of the research area. However, the use of three-dimensional well network injection wheel recovery changes the streamline field, produces the effect of fluid flow diversion, expands the water drive sweep coefficient, and improves the recovery rate. Chemical plugging can effectively replace water drive oil recovery and will become the main method for improving the recovery rate of such reservoirs in the lower part.