Abstract：As oil exploration and development advance to greater depths, reservoir rock strength increases, and perforation detonation energy rises, exacerbating damage to the cement sheath ring and compromising its integrity. Existing research has primarily focused on the properties and parameters of the cement sheath itself, with limited studies investigating cement sheath damage specifically from the perspective of shaped charge jet parameters. Leveraging the advantages of the Smoothed Particle Hydrodynamics (SPH) method in simulating crack propagation and damage accumulation, this study establishes an SPH model to investigate the effects of reflected wave strength under both free and fixed boundary conditions, as well as different jet parameters, on damage to cement targets. A self-programmed method was developed to quantify the extent of target damage, termed the damage ratio.Analysis results indicate that the damage ratio of targets with free boundaries is 9.35% lower than that with fixed boundaries. As jet density increases, the target damage ratio also increases: when penetration does not occur, the damage ratios are 10.8% and 15.9%; upon penetration, the damage ratio rises significantly to 55.0% and 64.7%. When the jet diameter increases from 1 mm to 2 mm, the damage ratio shows a substantial increase; however, further increases in jet diameter result in negligible changes to the damage ratio. At jet velocities between 2000 m/s and 3000 m/s, targets are not fully penetrated, and the damage ratio exhibits an increasing trend. At higher velocities that achieve penetration, the damage ratio decreases rapidly.The findings demonstrate that jet density and velocity are the primary factors influencing target damage. Under the condition that jet penetration is achieved, the extent of target damage increases with density but decreases with velocity. This study establishes a methodology for analyzing crack propagation and damage in cement targets and proposes a self-programmed quantitative analysis method for assessing damage. The results can also provide valuable insights for the optimized design of low-damage shaped charges and the optimization of perforation parameters.
2026, Vol. 47 
