Quantifying the influence of fracture parameters on flow behavior and pressure propagation in complex networks of discrete fractures within low-permeability reservoirs

Abstract

Fractures in low and ultra-low permeability reservoirs create a complex network, affecting fluid flow patterns and pressure propagation. However, limited research exists on fluid flow patterns and the impact of fracture properties on pressure within these networks. To address this, we introduce fracture shadow area and fracture penetration ratio concepts derived from studying single fracture reservoirs. Using a sophisticated model of a complex fracture network, we analyze how various fracture properties influence fluid flow patterns and reservoir pressure. Fractures are classified into five categories based on the development level. Through orthogonal experiments and multiple regression methods, we derive a formula that quantifies the pressure influence. We find that longer and denser cracks enhance fluid exchange and pressure propagation capacity. Moreover, increasing crack opening expands the area of pressure drop. Notably, fractures aligned with pressure propagation significantly decrease reservoir pressure. The hierarchical sequence of crack traits with the greatest influence is identified as crack length, crack opening, crack density, and crack angle. Our findings shed light on the intricate relationship between fracture properties and pressure dynamics.