Experimental and numerical investigation on repairing process of cement-casing repaired by rolling reshaper

In oil field, the bit weight (repairing force) and torque are always determined by experience when the rolling reshaper is used to repair the deformed casing. However, if the repairing force and torque are unreasonable, it will easily give rise to the secondary damage of deformed casing and surrounding cement sheath as well as pipe sticking. Hence, based on the elastic-plastic theory, the three-dimensional finite element model which can simulate the repairing process of cemented casing repaired by rolling reshaper has been presented in this paper by adopting the finite element method. Based on this model, the whole repairing process of cemented casing with elliptic section has been simulated, by which the deformation law of cemented casing, the repairing force and torque required to repair the cemented casing have been obtained in the repairing process. Meanwhile, based on self-developed testing equipment, the full-scale repairing experiment of cemented casing has been conducted by using rolling reshapser, and the correlations between deformation laws of cemented casing and repairing force and torque have been analyzed. As the test results are consistent with the simulation results, it indicates that the finite element model is accurate and reliable so that the research results can provide important reference for design and optimization of technological parameters.