The propagation mechanism of elastoplastic hydraulic fracture in deep reservoir

Abstract

Abstract The oil and gas industry is increasingly focusing on exploring and developing resources in deep earth layers. At high temperatures, confining pressures, and geostress differences, rock has the mechanical characteristics of plastic enhancement, which leads to the unclear mechanism of hydraulic fracture expansion. The current fracturing model and construction design lack pertinence, and the fracturing reform is difficult to achieve the expected effect. This paper established a model of elastoplastic hydraulic fracture propagation in deep reservoirs. It considered the enhancement of plasticity by examining the elastoplastic deformation and nonlinear fracturing characteristics of the rock. The results confirmed that the hydraulic fractures in deep reservoirs propagated due to plastic energy dissipation after fracture tip passivation, while the stress concentration declined, which increased propagation resistance. The relationship between geology, engineering factors, degree of plasticity, and fracture propagation is discussed, while the conditions that promote fracture propagation are analyzed to provide theoretical support for deep reservoir fracturing design.

Keywords

• Deep reservoir
• Elastoplastic constitutive model
• Nonlinear fracture
• Crack propagation
• Plastic enhancement