This PhD will form part of a larger industry sponsored project developing smart pumping technology capable of delivering controlled location specific fluid pulses to rock. The aim of the overall project is to further develop methods of hydraulically stimulating rocks in an environmentally sensitive way. The smart pumping technology will allow fluid pressure to be applied to the rock mass either conventionally as a static load, through cyclical loading using different rates of multiple pressure increase and decrease, through pressure wave superposition delivering a water hammer, and through controlled frequency oscillation delivering spatially distributed water hammer to the rock formation.
This PhD will investigate experimentally and model the near field geomechanical and hydro-mechanical effects of the different types of managed thermal (heat and cold) and pressure signals applied to a rock mass. Fractures which have undergone small scale shear are known to demonstrate enhanced permeability due to the resulting mismatch in the fracture aperture profile. That shear can be induced through thermal stress and through localised fluid pressure application.
Using the unique and state of the art GREAT cell (McDermott et al. 2018; Fraser Harris et al. In Review) the successful student will investigate the impact of thermal and hydraulic signals on the near field permeability, and recover worldwide unique experimental data comprising strain data, permeability measurements thermal measurements under different insitu true triaxial reservoir stress conditions. Analogue samples (20 cm x 20 cm diameter) of typical reservoir rocks found in geo-energy applications such as crystalline rocks for geothermal reservoirs, and low permeability shale rocks will be investigated. The samples will be fractured under different stress states, from simple tensile under unconfined conditions to fully reservoir like triaxial conditions. Fluid flow through the fractures and fracture networks developed will be investigated under different dynamic loading conditions.
Using state of the art finite modelling techniques, (Fraser Harris et al. 2015; Kolditz et al. 2012; McCraw et al. 2016) the PhD project should investigate which combinations of loading are likely to lead to the highest amount of near well stimulated permeability increase in different rock types.
Fraser Harris, A. P., C. I. McDermott, G. D. Couples, K Edlmann, A. Lightbody, M. Fazio, and M. Sauter. In Review. 'Experimental Investigation of Hydraulic Fracturing and Stress Sensitivity of Fracture Permeability under Changing True-triaxial Conditions', Journal of Geophysical Research - Solid Earth.
Fraser Harris, A. P., C. I. McDermott, O. Kolditz, and R. S. Haszeldine. 2015. 'Modelling groundwater flow changes due to thermal effects of radioactive waste disposal at a hypothetical repository site near Sellafield, UK', Environmental Earth Sciences, 74: 1589-602.
Kolditz, O., S. Bauer, L. Bilke, N. Böttcher, J. O. Delfs, T. Fischer, U. J. Görke, T. Kalbacher, G. Kosakowski, C. I. McDermott, C. H. Park, F. Radu, K. Rink, H. Shao, H. B. Shao, F. Sun, Y. Y. Sun, A. K. Singh, J. Taron, M. Walther, W. Wang, N. Watanabe, Y. Wu, M. Xie, W. Xu, and B. Zehner. 2012. 'OpenGeoSys: An open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media', Environmental Earth Sciences, 67: 589-99.
McCraw, Claire, Katriona Edlmann, Johannes Miocic, Stuart Gilfillan, R Stuart Haszeldine, and Christopher I McDermott. 2016. 'Experimental investigation and hybrid numerical analytical hydraulic mechanic