Abstract：Casing damage during blowout of water injection well is common in many oil fields of China. In order to study the mechanism of the casing damage，fluid-solid coupling models for simulating casing stress and deformation are established，and the numerical simulation based on the finite element method is also given. By numerical simulation，the effects of relief discharge，geo-stress，fluid pressure difference，permeability，stratum thickness on casing extrusion pressure are studied. The simulation results show that，at the same relief discharge，the bigger the permeability is，the bigger the extrusion pressure of casing damage is. In the same geological condition，the smaller the oil reservoir thickness is，the bigger the extrusion pressure is. The simulation results are very helpful to the casing protection in oil fields.
