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Ashley Stanton-Yonge

“Field structural mapping; numerical modelling & experimental work to explore permeability development of rocks under different loading scenarios”

PhD project title:

Tridimensional stress and the development of structural permeability.


 
Ashley Stanton-Yonge
Project description:

Fluid distribution in the crust is strongly controlled by structural permeability developed under the prevailing stress field (e.g. Sibson 1996; Faulkner and Armitage 2013). Fault-fracture meshes form potential pathways for large volume flow of hydrothermal fluids (e.g. Caine et al., 1996; Cox 1999), controlling geothermal reservoir development and ore deposit formation. Within these mesh conduits, strong directional permeability can develop in the direction of greatest fracture connectivity, associated with the intermediate stress axis (σ_2 ), because it is the orientation at which mode I fractures and shear fractures will likely intersect (e.g. Sibson 1996; Cox 2010).

My work aims to improve the understanding of fracture-fluid interaction and the variables controlling the fluid transport process within the brittle crust. My focus is on the tridimensional stress states developed under various tectonic settings along with the interaction of nearby faults and the consequent development of structural permeability through the creation, coalescence and intersection of fractures.
This research is carried out through a combination of field structural mapping, numerical modeling using the boundary element method (BEM) and experimental work using hydrostatic and true triaxial permeameter apparatus. Through this combined approach, permeability development of rocks under different loading scenarios is explored and quantified in the laboratory and up-scaled through numerical simulations and field observations.

References:
Caine, Jonathan Saul, James P. Evans, and Craig B. Forster. "Fault zone architecture and permeability structure." Geology 24.11 (1996): 1025-1028.

Cox, Stephen F. "Deformational controls on the dynamics of fluid flow in mesothermal gold systems." Geological Society, London, Special Publications 155.1 (1999): 123-140.

Cox, S. F. "The application of failure mode diagrams for exploring the roles of fluid pressure and stress states in controlling styles of fracture‐controlled permeability enhancement in faults and shear zones." Geofluids 10.1‐2 (2010): 217-233.

Faulkner, D. R., and P. J. Armitage. "The effect of tectonic environment on permeability development around faults and in the brittle crust." Earth and Planetary Science Letters 375 (2013): 71-77.

Sibson, Richard H. "Structural permeability of fluid-driven fault-fracture meshes." Journal of Structural Geology 18.8 (1996): 1031-1042.