Numerical simulation of hydraulic fracturing in circular holes

Hadi Haeri , Vahab Sarfarazi , Ahmadreza Hedayat , Zheming Zhu

Abstract

For investigating the effect of the pre-existing joints on the initiation pattern of hydraulic fractures, the numerical simulation of circular holes under internal hydraulic pressure with a different pattern of the joint distributions are conducted by using a finite element code, FRANC2D. The pattern of hydraulic fracturing initiation are scrutinized with changing the values of the joint length, joint offset angle. The hydraulic pressures with 70% of the peak value of borehole wall breakout pressure are applied at the similar models. The simulation results suggest that the opening-mode fracture initiated from the joint tip and propagated toward the borehole for critical values of ligament angle and joint offset angle. At these critical values, the crack grow length is influenced by joint ligament length. When the ligament length is less than 3 times the borehole diameter the crack growth length increases monotonically with increasing joint length. The opening-mode fracture disappears at the joint tip as the ligament length increases.

Key Words

ligament angle; pre-existing joints; opening-mode fracture; hydraulic fractures; joint offset angle

Address

Hadi Haeri — Young Researchers and Elite Club, Bafgh Branch, Islamic Azad University, Bafgh, Iran
Vahab Sarfarazi — Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran
Ahmadreza Hedayat — Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, USA
Zheming Zhu — College of Architecture and Environment, Sichuan University, Chengdu 610065, China

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