The role of rock joint frictional strength in the containment of fracture propagation

Abstract

The fracturing phenomenon within the reservoir environment is a complex process that is controlled by several factors and may occur either naturally or by artificial drivers. Even when deliberately induced, the fracturing behaviour is greatly influenced by the subsurface architecture and existing features. The presence of discontinuities such as joints, artificial and naturally occurring faults and interfaces between rock layers and microfractures plays an important role in the fracturing process and has been known to significantly alter the course of fracture growth. In this paper, an important property (joint friction) that governs the shear behaviour of discontinuities is considered. The applied numerical procedure entails the implementation of the discrete element method to enable a more dynamic monitoring of the fracturing process, where the joint frictional property is considered in isolation. Whereas fracture propagation is constrained by joints of low frictional resistance, in nonfrictional joints, the unrestricted sliding of the joint plane increases the tendency for reinitiation and proliferation of fractures at other locations. The ability of a frictional joint to suppress fracture growth decreases as the frictional resistance increases; however, this phenomenon exacerbates the influence of other factors including in situ stresses and overburden conditions. The effect of the joint frictional property is not limited to the strength of rock formations; it also impacts on fracturing processes, which could be particularly evident in jointed rock masses or formations with prominent faults and/or discontinuities.

Short‐term failure mechanism triggered by hydraulic fracturing

“…The risk of earthquakes triggered by hydraulic fractures is closely related to the stress state of rock strata and the development of fractures . It determines whether to initiate new tensile fractures or the propagation of preexisting fractures dominates the failure . Wang and Li et al found that hydraulic fractures interacted with random microfractures will make the complex geometry.…”

“…38,39 It determines whether to initiate new tensile fractures or the propagation of preexisting fractures dominates the failure. 8,22,[40][41][42][43] Wang and Li et al 38 found that hydraulic fractures interacted with random microfractures will make the complex geometry. Li et al 42 investigated the hydraulic fracturing process of granite with different orientations of two precut flaws by analyzing the acoustic emissions data.…”

Hydromechanical reactivation of natural discontinuities: mesoscale experimental observations and DEM modeling

“…Depending on various parameters, (1) the hydraulic fracture can cross the natural fracture, (2) it can be stopped by the natural fracture, or (3) it hydraulically activates the natural fracture. Microseismic imaging of hydromechanical reactivation of fractures is a useful tool to assess fracture geometry, i.e., the fracture height, length, orientation [40], frictional properties [23], and fractures interaction [47,54,56]. However, the interpretation of the induced microseismicity is not straightforward since pore pressure perturbations can promote both seismic and aseismic motions [14] with the induced slip not necessarily being the source of instability [35].…”

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

“…A rising tide of evidence from practical treatment in the field implies that hydrofracturing cracks may initiate and grow in a complicated way that is highly affected by the complexity of in‐situ stresses and the heterogeneity of reservoir formations . Some factors play critical roles in the optimisation and evaluation of hydraulic fracturing stimulation, namely, crack types (tensile or shear), the reasons for crack nucleation, propagation, and coalescence in deep reservoirs, the effects of heterogeneous gravels, and in‐situ stresses . It is known that the initiation and growth behaviours of hydrofracturing cracks are strongly influenced by the heterogeneity of reservoir rocks such as glutenite that is found extensively in tight gas reservoirs .…”