1 Jul 2017
1 Dec 2017 (Extended to 10 Jan 2018)
15 Jan 2018
16 Apr 2018 (Extended to 15 Jun 2018)
From 16 July 2018
By 17 September 2018
Department of Energy and Mineral Engineering, Geosciences, G3 Center and EMS Energy Institute, Pennsylvania State University, University Park, USA
Wed-31 Oct 2018 | 09:30 – 10:00 | Summit 2
"Key Complex Process Couplings and Challenges in the Effective Recovery of Deep Geothermal Energy"
Despite attempts to engineer viable deep reservoirs for the recovery of thermal energy at high enthalpy and mass flow rates – dating back to the 1970s – this goal has been surprising elusive. The record is replete with failed attempts, examples on life support and some successes. The key difficulties are in (i) accessing the reservoir inexpensively and reliably at depth, (ii) in penetrating sufficiently far through the reservoir, and (iii) in stimulating the reservoir in a controlled manner to transform permeability from microDarcy to higher than milliDarcy levels with broad and uniform fluid sweep and (iv) to create and retain adequate fluid throughput and heat transfer area throughout the project lifetime. We discuss key controls on permeability evolution in such complex systems where thermo-hydro-mechanical-chemical and biological (THMC-B) effects and feedbacks are particularly strong. At short-timescales of relevance, permeability is driven principally by deformations – in turn resulting from changes in total stresses, fluid pressure or thermal and chemical effects. These deformations may be intrinsically stable or unstable, result in aseismic or seismic deformation, with resulting changes in permeability conditioned by the deformational mode. We report experiments and models to represent the respective roles of mineralogy, texture, scale and overpressures on the evolution of friction, stability and permeability in fractured rerervoirs. The physics of these observed behaviors are explored via parametric studies and analyses.
Derek Elsworth is a professor in the Departments of Energy and Mineral Engineering and of Geosciences and the Center for Geomechanics, Geofluids, and Geohazards. His interests are in the areas of computational mechanics, rock mechanics, and in the mechanical and transport characteristics of fractured rocks, with application to geothermal energy, the deep geological sequestration of radioactive wastes and of CO2, unconventional hydrocarbons including coal-gas, tight-gas-shales and hydrates, and instability and eruption dynamics of volcanoes.