Artificial Interference of Stress Field in a Near‐Fracture Zone by Water Injection in a Preexisting Crack

Abstract

The in situ stress has an important influence on fracture propagation and fault stability in deep formation. However, the development of oil and gas resources can only be determined according to the existing state of in situ stress in most cases. It is passive acceptance of existing in situ stress. Unfortunately, in some cases, the in situ stress conditions are not conducive to resource development. If the in situ stress can be interfered in some ways, the stress can be adjusted to a more favorable state. In order to explore the method of artificial interference, this paper established the calculation method of the in situ stress around the cracks based on fracture mechanics at first and obtained the redistribution law of the in situ stress. Based on the obtained redistribution law, attempts were made to interfere with the surrounding in situ stress by water injection in the preexisting crack. On this basis, the artificial stress intervention was applied. The results show that artificial interference of stress can effectively be achieved by water injection in the fracture. And changing the fluid pressure in the crack is the most effective way. By stress artificial intervention, critical pressure for water channelling in fractured reservoirs, directional propagation of cracks in hydraulic fracturing, and stress adjustment on the structural plane were applied. This study provides guidance for artificial stress intervention in the exploitation of the underground resource.

An Investigation into the Effects of Weak Interfaces on Fracture Height Containment in Hydraulic Fracturing

“…On the contrary, if the fracture is expected to be confined to the pay zone, normal stress should be reduced, and shear stress should be increased. By controlling the geometry of the adjacent fracture and the fluid pressure, we can artificially intervene in the stress [34]. In research on fracture direction control during secondary fracturing, there is a series of studies on the relationship between stress field reconstruction and fracture direction [35][36][37][38][39].…”