Collaborative Research: Coupled Thermal-Hydrological-Mechanical-Chemical-Biological Experimental Facility at DUSEL Homestake

This project will develop a preliminary design and work-breakdown-structure for a large-scale subsurface experimental facility to investigate coupled thermal-hydrological-mechanical-chemical-biological processes in fractured rock at depth. The experiment will be part of the proposed Deep Underground Science and Engineering Laboratory (DUSEL) in the Homestake Mine, South Dakota. Many natural and engineered earth systems involve coupling of multiple processes in rocks that vary across a wide range of scales. The most pervasive process in the Earth?s crust that gives rise to strongly coupled phenomena is the flow of fluids (water, CO2, hydrocarbons, magmas) through fractured heated rock under stress. Understanding changes in the reactivity, deformability, life-supporting and transport properties of rocks that fluids infiltrate is important in a broad range of geological engineering and geological science endeavors. Despite this fundamental importance, the interactions remain poorly understood.

The project will: (1) Determine properties of Homestake rocks: geological, geochemical, mechanical, thermal, isotopic, and reactivity. (2) Upscale these data to elucidate transport mechanisms (conductive versus convective), natural reaction rates in fractures, and microbial community evolution. (3) Evaluate monitoring strategies, in-situ probes and sampling methods, and necessary measurements. (4) Select a candidate site for the evaluating coupled processes. (5) Develop a work-breakdown-structure. (6) Develop a coupled numerical model to evaluate potential effects on the rock mass and optimal heater configuration, power, and monitoring borehole orientations.

The models and insight from these experiments will have broad applicability to engineered systems, e.g., enhanced geothermal systems, CO2 sequestration and subsurface contaminant transport. Educational outreach will involve facility tours and a traveling benchscale ?mock-up? demonstration experiment.