Numerical simulation of fracture propagation in child wells considering dual-stress field

Abstract

Shale gas can easily generate interwell fracture hits during fracturing and stimulation, which might significantly interfere with the production of parent wells. Therefore, it is crucial to clarify the mechanism of fracture hits between wells to advance the technology for controlling fracture hits. In this study, considering the nonuniform stress field after parent well production, a numerical model of fracture propagation in a dual-stress field was established using the extended finite element method, and the fracture propagation behaviour of interwell fracturing was analysed. The results show that when the hydraulic fractures of the child well reach the low-stress zone generated during the parent well production, the fracture propagation accelerates, and the fracture propagation on both sides of the child well is nonuniform. The fracture length is mainly influenced by the minimum horizontal principal stress. The more significant the difference in the in situ stress of the reservoir and the more developed the natural fractures, the more prone the child well becomes to fracture hits. Controlling the operation scale and optimising well spacing patterns can effectively prevent or minimise the influence of fracture hits.

Keywords:

• Shale gas
• fracture hits
• fracture propagation
• dual-stress field
• extended finite element

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant Nos. 51804266 and 51874250 and the CNPC Innovation Fund under Grant No. 2019D-5007-0203.