3D MODELING OF FRACTURE INITIATION FROM CEMENTED PERFORATED WELLBORE

摘要

This paper presents some results of a 3D modeling of a fracture initiation from a cased and cemented wellbore with an explicit consideration of the interaction between the rock and the steel and cement layers under fluid pressure applied inside the wellbore. The equations of linear elastic equilibrium are used for the rock stress-state determination. The elasticity problem is split into two subproblems. One of them is set for a piecewise homogeneous elastic body, and the multiregion 3D boundary element method is utilized for its solving. The final problem solution is represented as the sum of the solutions of the subproblems, and the maximum tensile stress criterion is used for the determination of the fracture initiation pressure. The influence of the perforation misalignment, in-situ stress and the prefracturing stress in the cement layer on the fracture initiation pressure, the location of the incipient fracture, and its initial direction is examined for the configurations of a horizontal and vertical wellbore with a single perforation.