“Measuring and modelling anisotropic crack damage and permeability evolution in rocks.”
PhD project title:
Measuring and modelling anisotropic crack damage and permeability evolution in rocks.
The stress field in Earth’s crust is complex and can both vary in magnitude and rotate over time. This is critically important for the mechanics of fault zones, volcanoes, and geothermal systems. Furthermore, the crustal stress field is anisotropic and fully triaxial in nature, so that resulting rock deformation occurs three-dimensionally. While a great deal of rock deformation research has investigated how stressing cyclicity leads to crack damage evolution, little work has considered the influence of time-dependent directional changes in stress. Hence, experiments under true-triaxial stress conditions, coupled with simultaneous measurements of anisotropic fluid flow, are essential to improve our fundamental understanding of the stability of faults and associated fluid migration.
This PhD project will integrate two key elements: (1) Experiments using the unique True Triaxial Deformation Apparatus at UCL. Experiments have only been conducted on dry rocks, this project will extend that to experiments on water-saturated samples that will incorporate simultaneous measurements of the anisotropic permeability that results from the evolution of anisotropic crack damage. (2) Quantitative modelling to upscale the observations, better understanding these processes at the field/reservoir scale.