Calculation and Experimental Study of Axial Loading of Casing Based on the Phase Transition Effect During Curing of Cement Slurry

In this paper, the casing strings of cement slurry during the curing period are taken as the research object in order to build a force model, with comprehensively considering the influence factors such as the phase transition heat transfer and volume change of the cement slurry during the curing period. The random contacts between casings and well walls were simulated by establishing a gap element between two phases of cement slurry. Formulas of axial loadings on the casings during curing of cement slurry were obtained using the finite element method. With this method and on-site measurement, the wellhead axial loads of three wells during cement slurry curing were calculated and tested. The results revealed that the maximum relative deviation between the theoretical prediction results by the model and the actual field test data was 10.42%, indicating that the model established is reliable. Finally, using the established finite element calculation method, the effects of the cementing section length on extra loadings on the wellhead were analyzed. This study serves as an accurate reference to calculations of extra loadings on the wellhead during curing of cement slurry and optimization of cementing section length, thus facilitating well cementation.