Equivalent external casing pressure in rheological strata

In order to provide a theoretical basis for the casing design of rheological strata,we examined three models of equivalent external casing pressure,one is from the current standard and the other two are the viscoelastic fluid model and viscoelastic solid model,respectively.Based on the calculation results of field example by these three models,we concluded that compared with the real data of case studies,the model from current standard and the viscoelastic fluid model gave the equivalent external pressure considerably lower,while the equivalent external pressure derived from the viscoelastic solid model fitted the actual field situation very well.