Precise three dimensions reconstruction closure experiment and a new apparent compliance model for self-propped fractures

Abstract

Fracture compliance, an essential indicator of fracture deformation, is also a key parameter for post-fracturing network diagnosis and inversion. However, current research lacks detailed experimental studies to acquire this vital parameter of fracture compliance, and the influence of fracture roughness and rock Young’s modulus on fracture compliance remains unclear, leading to a deficiency in models for the evolution of fracture compliance. Therefore, based on 3D reconstruction technology of fracture surfaces, an experiment was designed to observe the deformation of self-propped fractures, obtaining experimental data on fracture deformation. Utilizing this data, a new apparent compliance model for fractures was proposed. The results indicate that closure pressure is the decisive factor affecting the apparent compliance of fractures, regardless of their roughness. The influence of fracture roughness and rock Young’s modulus on apparent compliance shifts under varying closure pressures. At lower closure pressures, apparent compliance is primarily governed by fracture roughness—the greater the roughness, the higher the compliance. At higher closure pressures, the apparent compliance are mainly controlled by the rock’s Young’s modulus—the higher the modulus, the lower the compliance. This phenomenon is attributed to the elastic-plastic damage cycle during the compressive deformation of fractures.