Analysis of wells cement sheath stability during shaped charge perforating based on geomechanical modeling

Well cement sheath stability analysis for two oil-producing wells in the completion of productive formations by shaped charge perforating was performed. The data of direct measurements of pressures in the borehole at different distances from the cable head of the perforating tool at the moment of detonation, which exceeded 50 MPa, were used in the studies. The pressure values were approximated along the wellbore using a power law. To reliably predict the stress-strain state of the near-wellbore zone of the perforation interval, the ANSYS finite-element modeling software was used. To determine the stress field, an axisymmetric finite-element calculation scheme was built, the height of the model along the wellbore was 39 m. During modeling, it was taken into account that the geological and physical parameters of the simulated reservoirs differed in depth and reservoir pressure value were different. Elastic-strength properties of the cement stone formed were determined during the laboratory experiments for different recipes of cement slurries. According to the results of modeling, the areas of destruction and strength reserve of cement stone, as well as the values of radial displacement of the production casing in the perforation interval were determined. The developed model of the near-wellbore zone and methodical approaches can be used in future for choosing optimal elastic and strength properties of cement stone, perforation tools and technological parameters of perforating-explosive operations.