Development and Performance Evaluation of High Strength and High Temperature Resistant Plugging System for Repairing Casing Damage

Cement slurry used for plugging in casing damage has long been faced with problems such as low strength, weak corrosion resistance, and low one-time successful rate. It is urgent to develop new plugging materials for repairing casing damage. In this paper, a high strength and high temperature resistant plugging system was developed based on epoxy resin, by selecting the high temperature resistant curing agent and adjusting the dosage of promoter and thinner, which was used for well temperatures of 120 ℃. The gel time of the system was more than 4 h to ensure sufficient injection time. The compressive strength and tensile strength of the cured product were 134.69 MPa and 72.24 MPa, respectively. The cementation strengths between the system and the rock and set cement were at least higher than the tensile strengths of the rock and set cement itself. When the system bonded with the smooth steel column, the cementation strength on the vertical and parallel surfaces was 7.6 MPa and 8.31 MPa, respectively, which was much higher than that of cementation by cement. The thermal decomposition temperature of the cured product of the plugging system was more than 282 ℃, indicating that it has good temperature resistance performance. After soaking in acid, alkali, and salt, the cured product maintained the compressive strength and tensile strength above 110 MPa and 40 MPa, respectively. The plugging system meets long-term downhole application requirements and provides support for the repair technology of casing damaged well.