On the pressure decline analysis for hydraulic fractures in elasto-plastic materials

TL;DR

This paper investigates hydraulic fracture behavior in elasto-plastic materials using finite element simulations, demonstrating that pressure decline analysis methods are applicable even with inelastic deformation.

Contribution

It introduces a finite element-based approach to analyze hydraulic fractures in elasto-plastic materials and validates pressure decline analysis in this context.

Findings

Pressure decline analysis can identify closure stress in elasto-plastic materials.

Fracture evolution trends differ between elastic and elasto-plastic cases.

Standard pressure decline techniques are applicable to inelastic deformation scenarios.

Abstract

In this paper the problem of a plane strain hydraulic fracture in elasto-plastic material is analyzed. The analysis is based on Finite Element Method computations of crack propagation and closure to simulate the Mini-Frac calibration test. The basic trends of fracture evolution are identified for both, the propagation and the closure stage in elasto-plastic materials and compared with the results obtained for purely elastic deformation of rock. Pressure decline analysis is conducted to identify the closure stress and leak-off coefficient. The results show that the standard techniques of pressure decline analysis can be adopted also for the case where the fractured material deforms inelastically.