Study on different plugging agents in multi-stage water shutoff technology

At present, most oil wells in Changqing oilfield are producing crude oil by water injection. Because of the complexity of reservoir geological structure and heterogeneity of formation internal structure, it is easy to cause problems such as low water injection efficiency; rapid increase of water cut, and even water flooding. In recent years, the technique of multi-slug chemical water shutoff has attracted much attention due to its wide spread, long validity period and selective water shutoff. The difficulty of this technology is how to realize the different performance requirements of different slugs. In this paper, a self-designed multi-slug water shutoff technology system, according to the characteristics and requirements of different slugs developed a new plugging agent formula and performance testing. In this paper, a self-designed multi-slug water shutoff technology system, according to the characteristics and requirements of different slugs developed a new plugging agent formula and performance testing. The results show that the plugging agent has good stability, water absorption and expansion, and has a wide range. When the concentration of plugging agent in the main section exceeds 0.5%, the water shutoff rate can reach over 99%. The sealing section plugging agent is a micro-expansion cement system. The system has the characteristics of small size, good homogeneity and high plugging strength. It can be used to plug the reservoir with high squeezing pressure and weak formation absorption capacity. This paper can provide some data support for the design of multi-stage plugging technology and the study of plugging agent formulation.