Analysis on Wellhead Uplift by Tieback Casing String under Temperature Difference Effect

The wellhead uplift will lead to wellbore integrity damage of oil and gas wells and affect the safety of subsequent production of oil wells. In order to study the wellhead stress distribution and uplift height variation of the tieback casing string in cementing-production operation, with the help of the finite element method, based on the field working conditions of a well in Shunbei Block, the ABAQUS software was used to build a thermal-solid coupling analysis finite element model of multilayer casing-cement sheath-formation system under different working conditions, so as to analyze the stress and displacement variation of tieback casing from cementing stage to production. The analysis results show that as the cement top increases, the wellhead uplift height increases monotonously, indicating that as the severity of cement sheath loss increases, the longer the number of free sections of casing, the greater the height of elongation and uplift under temperature difference effect is; and as the cement top increases, the Mises stress of the tieback casing at the time of wellhead fixation increases first and then decreases, and does not show a monotonous increasing or decreasing trend. The study results provide some reference for the analysis of wellhead uplift phenomenon caused by field tieback casing string.