Numerical Simulation of Effects of Shock Waves on the Integrity of Cement Sheath

Abstract

Abstract With the application of electrical explosion technology in the oil industry, such as plugging removal, wax removal and micro-cracks generation near the wellbore zone, the impact of shock wave generated by the electrical explosion on cement sheath cannot be ignored. To study the effect of electrical explosion downhole application on the integrity of cement sheath during the operation, a numerical simulation was used. A composite model of casing-cement sheath-rock is established in AUTODYN. The propagation process of shock waves in the composite and the damage to cement sheath are studied. The results show that the shock wave propagates through the perforation hole in the liquid and keeps a high pressure in the perforated area. In the nonperforated area, the shock wave decays greatly after passing through the casing pipe. When the cement sheath and rock are subjected to the shock waves, the damage area extends outward from the perforation hole. The cement sheath and rock are mainly subjected to the tensile and shear damage by the shock waves. What is more, the casing deformation caused by shock waves may also contribute to the damage of cement sheath behind the casing.