3-D finite element analysis of casing loads in salt rocks of deep wells

The oilfield has suffered huge economic losses due to the creep of the salt rock deeply buried underground under the effect of certain earth stress and temperature,which causes the casing load to change with time and results in the casing deformation and shear.So a 3-D finite element analysis(FEA) mechanical model concerning salt rocks and cement mantles as well as casing couples is established in this paper to research the conditions and dimension of the earth stress and the effect of the abutment pressure of fluid in a borehole on the forces exerting on casing in salt rocks.The research shows that the casing load caused by the creep the salt rocks are inhomogeneous,which is the highest in the direction of the minimum earth stress.Therefore,it is greatly limited to calculate the casing external collapse load based on using overlying formation pressure.So in this paper,the new 3-D FEA model is applied to calculate the strength of the three kinds of intermediate casing in deep wells,ultra deep cementing wells and salt rocks.The calculating result is in agreement with the intermediate casing collapse of the oilfield,which proves that the newly established model is reasonable and will lay a solid theoretical basis for the strength design of casing in salt rocks of deep wells.