Numerical study on damage law and influencing factors of cement sheath under perforation conditions

The damage of the cement sheath is inevitable during the perforation process, and the physical parameters of the cement sheath have a great influence on the damage of the cement sheath. A three-dimensional numerical model, which was composed of perforating charge, casing-cement sheath, and formation and consistent with the engineering practice, was established, considering the dynamic characteristics of materials in the process of explosion impact. The numerical simulation results are verified by the physical model test, which shows that the compression and shear of the cement sheath caused by the penetration of the metal jet in the perforation operation is the main reason for the failure of the cement sheath. The compressive strength, tensile strength, shear modulus and density of the cement sheath directly affect the damage degree of the cement sheath. Increasing the compressive strength and tensile strength of the cement sheath, or reducing the shear modulus and density of the cement sheath, can reduce the damage of the cement sheath. The study revealed the influence of the physical properties of the cement sheath on the impact damage of the cement sheath during the perforation process, which has a certain reference value for the optimal design of the cement sheath.