Influence of components properties on sealing ability of cementing isolation system in deep-water shallow formation

Abstract In order to guarantee the safety of oil and gas exploration and development and ocean environment, the influence of components properties comprised of casing size, cement strength and formation strength on sealing ability of cementing isolation system in deep-water shallow formation was investigated by using the simulated cementing isolation system device in this paper. Results show that casing size has little effect on the sealing ability of cementing isolation system, and the sealing ability is not related to the casing size. When the cement strength is lower than formation, the cement strength decides the sealing ability, and the maximum sealing pressure of highest strength cement (2.15 MPa) is about 2 MPa. When the cement strength is higher than formation, the unconsolidated formation is the weakness and sealing failure area, and the maximum sealing pressure of highest strength formation (2.46 MPa) is about 3 MPa. Increasing the cement strength grade and extending the curing time can improve the sealing ability of cementing isolation system to a certain extent, however, solidifying and enhancing the loose formation is the most effective method to improve the sealing ability of cementing isolation system in deep-water shallow formation.