Study of the Crack Propagation Model Under Seepage–Stress Coupling Based on XFEM: Fid-Bau Portal

Study of the Crack Propagation Model Under Seepage–Stress Coupling Based on XFEM

Wang, Chao / Zhang, Qiang-Yong

Abstract In fractured-vuggy reservoirs, cracks are not only reservoir spaces but also seepage channels. They are more likely to be closed and cracked under the coupling of the seepage field and the stress field. Therefore in this paper fractured-vuggy reservoirs are analyze as the background to study the propagation and closure of cracks under the seepage–stress coupling model. Firstly, the hydraulic model of continuous-discrete medium is established. Secondly, the fracture mechanics method is used to obtain the expression of crack width in the process of propagation and closure with the consideration of the water pressure, and then the propagation and closure criterions are established. On this basis, a numerical simulation method of crack propagation and closure under the seepage–stress coupling model is proposed by using the XFEM, and it is realized in ABAQUS by the secondary development. The calculation of typical cracks shows that: (1) the numerical calculation method established in this study is effective to simulate the propagation and closure of cracks; (2) the direction of crack propagation under Darcy flow is parallel to the vertical stress, and the direction of the crack propagation under the non-Darcy flow is perpendicular to the original fracture. (3) Non-Darcy flow is more likely to cause the whole system to become unstable than the Darcy flow does. This research has great significance for the future experimental researches, theoretical analyses and engineering applications.