Study on Effect of Perforation Orientation on Hydraulic Fracturing of Shale

Jian Li,Dong Wang,Qingqing Ma,Qi Qiao,Fei Zhao,Hongjian Wang,Zhiyang Yao,Bing Hou

doi:10.1155/2022/6130848

Abstract

The core technology to realize the development of unconventional oil and gas resources is the large-scale volume transformation of shale reservoirs, but volume fracturing is a complex physical and mechanical process, and its mechanism remains to be further studied. In this paper, starting from the current research status of shale volumetric fracturing, the perforation orientation of volumetric fracturing is numerically simulated by using the finite element software. The following conclusions are drawn: ① when the ground stress conditions are equal, with the increase of perforation angle, the maximum principal stress at the front of perforation decreases gradually; that is, when the perforation is along the horizontal minimum principal stress, the maximum principal stress at the front of perforation is the largest, which is most conducive to fracturing of shale reservoirs. ② When the perforation is along the direction of the horizontal minimum principal stress and the horizontal stress difference is zero, the smaller the horizontal stress, the greater the maximum principal stress at the front of the perforation. Therefore, the smaller the horizontal stress, the more conducive to the rupture of shale reservoirs. ③ When the perforation is along the horizontal minimum principal stress, the maximum principal stress at the front of the perforation increases with the increase of the horizontal stress difference. Therefore, the larger the horizontal stress difference, the more favorable for the fracture of shale reservoirs.

Highlights

2 When the perforation is along the direction of the horizontal minimum principal stress and the horizontal stress difference is zero, the smaller the horizontal stress, the greater the maximum principal stress at the front of the perforation
3 When the perforation is along the horizontal minimum principal stress, the maximum principal stress at the front of the perforation increases with the increase of the horizontal stress difference
The conclusions are revealed through numerical research: (1) When the ground stress conditions are equal, with the increase of perforation angle, the maximum principal stress at the front of perforation decreases gradually; that is, when the perforation is along the horizontal minimum principal stress, the maximum principal stress at the front of perforation is the largest; so, it is most conducive to the fracturing of shale reservoirs

Summary

Research Status of

Foreign fracturing technology mainly includes [1–4] the following: nitrogen foam fracturing technology, the technology first began in January 1968, in the United States and Canada on the extensive use of foam fracturing technology, and foam fracturing is suitable for low pressure and low permeability water sensitive formation [5]; water fracturing technology, which uses water to add appropriate drag reduction agent as fracturing fluid, can save 30% of the cost without reducing production and has achieved good application results in the transformation of low permeability reservoirs [6]; and synchronous fracturing technology is the latest fracturing technology which has been successfully applied in the development of Barnett shale gas in Vosburg Basin in recent years. Pneumatic fracturing technology and polymer hollow thermal expansion support technology were proposed, which were different from conventional shale reservoir reconstruction methods

Research Status of Numerical Simulation of Hydraulic Fracturing

Findings

Conclusion