Abstract
AbstractThis study presents a probabilistic analysis of 3D Navier‐Stokes (NS) fluid flow through 30 randomly generated sheared fractures with equal roughness properties (Hurst exponent = 0.8). The results of numerous 3D NS realizations are compared with the highly simplified local cubic law (LCL) solutions regarding flow orientations and regimes. The transition between linear and nonlinear flow conditions cannot be described with a generally valid critical Reynolds number , but rather depends on the individual fracture's void geometry. Over 10% reduction in flow is observed for increased global Re (>100) due to the increasing impact of nonlinear conditions. Furthermore, the fracture geometry promotes flow anisotropy and the formation of channels. Flow perpendicular to the shearing leads to increased channeling and fluid flow (∼40% higher) compared to flow parallel to the shearing. In the latter case, dispersed flow and irregular flow paths cause a reduction of LCL validity.
Highlights
The investigation of fluid flow regimes in naturally fractured rock is crucial for assessing the performance of underground operations
This study presents a probabilistic analysis of 3D Navier-Stokes (NS) fluid flow through 30 randomly generated sheared fractures with equal roughness properties (Hurst exponent = 0.8)
The fluid flow in the NS simulations is evaluated at each fractures' outlet to be able to consider both small-scale local disturbances as well as fracflow to the shearing direction, and lighter colors indicate larger pressure gradients. (b) Boxplot of the flow anisotropy (FA)
Summary
The investigation of fluid flow regimes in naturally fractured rock is crucial for assessing the performance of underground operations. The flow regime is controlled by the complexity of the internal fracture morphology (i.e., roughness) and the interaction and intersection of different fractures (structural complexity). The classical cubic law (CL) relationship assumes the fracture void space (aperture) as the volume confined by parallel plates (Witherspoon et al, 1980), whereas geological processes, such as shearing of rough opposing surfaces (Auradou et al, 2005) or mineral reactions (Schmidt et al, 2017), lead to laterally variable fracture apertures. Since LCL is a cubic function of local apertures resulting from an arbitrary roughness distribution, the computed flow rate is highly sensitive to the proper definition of these apertures: an aperture vertical to the overall fracture plane is commonly used
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
