Preparation and Performance Evaluation of Self-Degrading Temporary Plugging Agent for Well Workover of Fractured Reservoir

Abstract The temporary plugging technology is considered an important technology in the well workover process of oil and gas reservoirs. Gel is a frequently employed temporary plugging agent in oilfields; however, it has drawbacks, including poor cross-linking strength, unpredictable gelation duration, and considerable reservoir damage after application. To solve these issues, this study seeks to create a gel-based temporary plugging agent system that will improve the dependability and efficiency of oilfield development. In the study, acrylamide, hydrophobic monomers, initiators, crosslinkers, inorganic components, and scale inhibitors were used to formulate the temporary plugging agent. To close underground channels, the prepared plugging agent is injected into the underground and gels at high temperatures. In this study, the elastic modulus of the gel was investigated with a HAAKE rheometer, and the core flooding test was carried out to evaluate the plugging efficiency of the gel. Meanwhile, the visual code method was used to observe the formation time of the temporary plugging agent, and the self-degradation performance of the temporary plugging agent was studied. Hydrophobic monomers and inorganic materials significantly enhance the mechanical properties of the temporary plugging agent after forming the glue. The elastic modulus after crosslinking can reach about 450 Pa, and the maximum pressure of plugging can reach 2.4 MPa. The crosslinking time can be controlled within 30 minutes to 10 hours by adding the inhibitor. The crosslinking agent used in the system is ester organic matter, which can be hydrolyzed at high temperatures to achieve self-degradation performance, so that the degradation rate of the temporary plugging agent can reach 90% within 7 days after forming the glue. This temporary plugging agent has high strength, a controlled crosslinking time, and good self-degradation performance as compared to the typical gel-type temporary plugging agent. These qualities are crucial for reservoir protection and well workover.