Numerical study of hydraulic fracturing near a wellbore using dual boundary element method

• Published in: International journal of solids and structures Vol. 239-240; p. 111479
• Main Authors: Cheng, Shaoyi, Zhang, Ming, Zhang, Xi, Wu, Bisheng, Chen, Zhaowei, Lei, Zhengda, Tan, Peng
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 15-03-2022; Elsevier BV
• Subjects: Boundary element method; Boundary integral method; Crack propagation; Dual boundary element method; Finite volume method; Fluid dynamics; Fluid flow; Fluid–solid coupling; Hydraulic fracturing; Inclination angle; Integral equations; Mathematical models; Permeability; Viscosity; Dual boundary element method; Fluid–solid coupling; Hydraulic fracturing; Crack propagation
• ISSN: 0020-7683; 1879-2146
• DOI: 10.1016/j.ijsolstr.2022.111479

The pattern and path of hydraulic fracture (HF) from a wellbore circumference have a great impact on subsequent formation of complex fracture networks highly desired for permeability enhancement of unconventional reservoirs. In this paper, a new fully coupled hydraulic fracturing model is developed in the framework of the dual boundary element method (DBEM) that describes the deformation of rock matrix and the finite volume method that simulates the fluid flow in the fracture and the distribution of injection rate among fractures. The DBEM applies displacement boundary integral equation to one crack surface and traction boundary integral equation to the other one. The model presented is first validated against the existing semi-analytical and numerical solutions for single fracture in an infinite domain, and shows excellent agreements with a relative error less than 1% for injection pressure and half fracture length. Then the problem of multiple HFs including natural fractures (NFs) cutting the wellbore is investigated. It is shown that a larger product of fluid viscosity and injection rate or a small in-situ stress difference can smooth the fracture path and enhance the fracture opening. In the presence of multiple fractures, the HF and NF competes in growth, and the results show that the initial permeability and inclination angle of NF can alter the propagation preference from HF to NF. In particular, a large fluid viscosity and a more isotropic stress condition will propagate both NFs and HFs simultaneously.