Elastoplastic damage analysis and structural optimization of soluble bridge plug based on phase field method

Abstract

Bridge plugs play a crucial role as a plugging tool for downhole staging in the staged fracturing process. In particular to the soluble bridge plug, which can be automatically dissolve in that backflow fluid after hydraulic fracture. In this paper, a single silp with small diameter soluble bridge plug is designed to take into account its passability in the casing deformation well. A three-dimensional phase field model of the elastoplastic anchoring mechanism was developed to investigate the maximum pressure-bearing of the designed soluble bridge plug during the fracturing and optimize its structure. The phase field model we use is suitable for linear isotropic hardening materials, in which the elastic energy is decomposed into compression and tension parts, and the plastic energy is decomposed into plastic free energy and plastic dissipation energy. The model is assumed to be quasi-static. Tensile experiments with two asymmetrically notched metal bars are used to verify the applicability of our model to materials with small plastic strains. The simulation shows that the designed bridge plug can adapt to the working pressure differential of 70 MPa, and the optimal number of slip teeth is 8 or 9.