Simulation of crack initiation and propagation in hydraulic fracturing of oil wellbore by maximum principal stress criterion

Iman Shafaeizadeh¹, Mohammad Reza Forouzan^*1, Lohrasb Faramarzi²

¹ Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran

² Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran

Abstract

A two-dimensional (2D) extended Finite Element Method (XFEM) simulation is presented for propagation of hydraulic fractures from wellbore that the minimum principal in-situ stress is in horizontal plane. One primary role of hydraulic fracturing is to provide a high conductivity pathway along which reservoir fluids can flow to the well. In this study, enriched element has been applied with a maximum principal stress damage criterion, for initiation and propagation of crack in Abaqus 6.12. The properties and input data for rock models were extracted experimentally from Ahwaz reservior- Bangestan wellbore specimens. The specifications of crack were studied by analyzing the rock model without any crack or flaw and under different condition, such as in-situ stresses, pore pressure and elastic modulus. The results show that the critical position of crack initiation is perpendicular to minimum principal in-situ stress and stress condition of borehole and by increasing the pore pressure to the rock models, the pressure of injection fluid decreases. The results show that the pressure of injection fluid decreases at initiation step to constant amplitude after crack propagation. These results are in close agreement with the theoretical data, so that our simple procedure is efficiency and flexible.

Keywords: Hydraulic Fracturing, Damage Mechanics, Extended Finite Element Method, Rock Mechanics