Nano-gel temporary plugging for high-temperature high-pressure gas wells of the Suqiao gas storage

In the Suqiao storage, the average reservoir depth of gas wells is near 5000 m, the formation temperature is 140 ℃–150 ℃, and the reservoir pressure under the injection-production condition is typically 35–45 MPa. The workover of gas wells requires a temporary well kill. However, conventional polymer gel-based plugging agents are intolerant of high temperature and prone to leak-off, which leads to unsatisfactory well-kill performance. Given this, the 150 ℃-tolerant nano gel was developed and the gelation performance, thermal tolerance, and rheology of such nano gel were evaluated. Furthermore, the nano gel temporary well kill testing was performed in two high-temperature high-pressure (HPHT) wells in the Suqiao storage. It was shown that this temporary plugging technique presents the advantages of simple operation, fast effects, and low costs, and can be extensively applied to temporary plugging of HTHP wells and profile control and water plugging of high-temperature oil and gas reservoirs.