Study on Effect of Perforation Orientation on Hydraulic Fracturing of Shale
By: Jian Li, Dong Wang, Hongjian Wang, Fei Zhao, Qingqing Ma, Qi Qiao, Zhiyang Yao (March 3, 2022)
This article delves into the intricate mechanisms of volume fracturing in shale reservoirs, a cornerstone technology for unconventional oil and gas resource development. Although volumetric fracturing is an integral part of harnessing these resources, its physical and mechanical processes are complex, necessitating further investigation. Utilizing finite element software, the paper conducts a numerical simulation on the perforation orientation in volumetric fracturing, leading to several crucial findings.
Firstly, under identical ground stress conditions, an increase in perforation angle leads to a gradual decline in the maximum principal stress at the perforation forefront. Specifically, when perforation aligns with the horizontal minimum principal stress, this stress is at its peak, making it the most advantageous for shale reservoir fracturing. Secondly, with perforation along the direction of the horizontal minimum principal stress and no horizontal stress difference, a decrease in horizontal stress results in a higher maximum principal stress at the perforation forefront. This means that lower horizontal stresses are more favorable for shale reservoir rupture. Lastly, with perforation maintaining its alignment with the horizontal minimum principal stress, the maximum principal stress at the perforation forefront escalates as the horizontal stress difference increases. This suggests that a greater horizontal stress difference is beneficial for the fracturing of shale reservoirs.