Numerical analysis of the hydrofracturing behaviour of heterogeneous glutenite considering hydro‐mechanical coupling effects based on bonded particle models

Abstract

The heterogeneity of tight reservoirs significantly influences hydrofracturing behaviours, such as crack morphology, type, initiation, propagation, and distribution. The accurate characterisation of the influencing mechanisms has become a pivotal issue in enhancing the fracturing stimulation of tight reservoirs, as well as in the prediction of tight oil and gas production. In this study, the hydrofracturing behaviours of heterogeneous glutenites and their influencing mechanisms were numerically investigated based on bonded particle models (BPMs). The geometry and mechanical properties of the natural glutenites were obtained using microfocus computed tomography (CT) and triaxial tests and were used to construct heterogeneous BPMs. The hydrofracturing behaviours of the heterogeneous BPMs under various in-situ stresses were analysed with hydro-mechanical coupling effects considered and compared with those of homogeneous BPMs under the same conditions. The numerical results show that gravels in heterogeneous glutenites inhibit crack propagation. The shear cracks that appear in the initial stage of crack development subsequently propagate and distribute around the injection hole, and there are fewer hydraulic shear cracks than tensile cracks. The crack morphologies of BPMs are found to be consistent with the experimental forms. The numerical simulation provides a way to understand the mechanisms that govern the hydrofracturing crack types and propagation of heterogeneous reservoirs.

Numerical Investigation of a Hydrosplitting Fracture and Weak Plane Interaction Using Discrete Element Modeling

“…Zhang [26] investigated the influence of F 0 variation on macro-permeability and pore pressure and then established a weak structural plane to form three different models of hydraulic crack contact with the weak structural plane. Yang [27] constructed a 3D model of heterogeneity of cylindrical sandstone samples through CT scanning, and then reconstructed it in 3D based on the bonded-particle model (BPM). Through a series of numerical simulations, they showed that heterogeneous sandstone particles inhibit crack growth.…”

Brittleness Evaluation of Glutenite Based On Energy Balance and Damage Evolution

“…The brittleness and fracability of glutenite are affected not only by the mechanical properties of matrix, but also by gravel size and volume content, and mechanical properties of different rock structures. Fracture propagation behavior and the hydraulic fracturing effect of glutenite reservoirs are controlled by mechanical properties [15,55,56], geological conditions [57][58][59][60], and technical parameters [60][61][62]. The effect of glutenite brittleness on hydraulic fracture propagation mechanisms and fracturing needs further study.…”

A Review of Hydraulic Fracturing Simulation

“…separation of elements). Using CDEM, Ju et al [159,160,162] studied 2D and 3D propagation of hydraulic fractures in heterogeneous glutenite, where the gravels and natural fractures captured using CT-scan are incorporated into the numerical models and show non-negligible influence on the fracture path.…”

“…More recently, CT-scan techniques have been increasingly used in experiments to detect natural fractures and stimulated hydraulic fracture network [40,125,162,196,198,397]. Liu et al [196] identified 3D propagation and distribution of hydraulic fractures in heterogeneous rocks and found the rock heterogeneity and horizontal in situ stress ratio have a significant influence on the stimulated fracture network.…”