GASCLAY · Formation and Vanishing of Discrete Gas Flow Pathways in Clays

The formation of Discrete Gas Flow Pathways (DGFP) is the mechanism whereby a gas phase penetrates a liquid-saturated clay-rich material in the form of narrow channels created by the mechanical action of the gas pressure. It is a very complex phenomenon, which is strongly affected by small and larger scale heterogeneities in the material, resulting in a partly random process. DGFP occur in a range of natural and engineered processes (e.g. release of methane from ocean or lake floor sediments, stimulation of sensitive hydro-carbon reservoirs, CO2 injection and storage in subsurface reservoirs, and gas migration through clay barrier in Geological Disposal Facilities for radioactive waste). Despite its multiple environmental and economic implications, the formation, development and vanishing of DGFP networks are poorly understood on a fundamental level.The objective of the proposal is to close this knowledge gap through a combined experimental and numerical modelling study. For this purpose, I will develop a new experimental setup to generate and visualise two-dimensional DGFP networks during gas injection tests. By using Particle Image Velocimetry, this setup will allow to track, for the first time, the formation and vanishing of DGFP as gas is injected. In addition, the setup will be simple enough to enable extensive parametric studies and probability distribution analysis, which are essential to unravel the random nature of the problem. Finally, the experimental results will be used to develop and validate a coupled hydro-pneumo-mechanical Finite Element model.The new theoretical framework, experimental setups and numerical model will provide the basis to develop new clay-based engineered materials, to increase the feasibility of engineering projects and to improve the global warming prognosis. In that way, this project will contribute to the European knowledge-based economy and to the European Climate Action.