Basic Research Needs for Geosciences - Energetics Meetings and ...

PRIORITY RESEARCH DIRECTION:FLUID-INDUCED ROCK DEFORMATIONFLUID-INDUCED ROCK DEFORMATIONABSTRACTGeologic carbon sequestration presents scientific challenges associated with the large pressuretransients induced by CO 2 injection, which affect the thermal, mechanical, hydrological, andchemical state of subsurface volumes that span hundreds to thousands of km 3 . Accurateforecasting of the effects requires improved understanding of the coupled stress-strain and flowresponse to injection-induced pressure and hydrologic perturbations in multiphase-fluid saturatedsystems. Such effects manifest themselves as changes in rock properties at the centimeter scale,mechanical deformation with length scales that reach tens of kilometers, and modified regionalfluid flow. Improved understanding of rock hydromechanical properties over this range of scaleswould lead to more accurate geomechanical modeling of multiphase-fluid saturated systems,permit improved coupling of chemical, mechanical, and hydrological processes, and potentiallyprovide new theoretical constructs for understanding shallow crustal deformation.EXECUTIVE SUMMARYCommercial-scale carbon capture and geologic storage requires injecting large volumes ofimpure CO 2 into the shallow crust for many decades. The volumes will be enormous: to reduceannual global greenhouse gas emissions by one gigaton of carbon requires cumulative subsurfaceinjection that exceeds current global oil production. This injection program will produce verylarge pressure transients that will deform the shallow crust and possibly displace ambient fluidsover large regions, thereby modifying regional hydrology. For example, faults may be activatedand fractures formed or opened, seismicity may be induced, and groundwater quality might bedegraded. Consequently, understanding shallow crustal deformation and multiphase fluid flowdriven by commercial-scale CO 2 injection is a priority research need.Innovative research in this area should focus on improved understanding of multiscalegeomechanical processes in the shallow crust, but must also include explicit account of thedependent thermal, hydrological and geochemical processes. The fundamental goals are:• Improved understanding of coupled stress, strain, and flow response to injection-inducedpressure transients in multiphase-fluid saturated systems at all scales• Improved geomechanical modeling of multiphase-fluid saturated systems• Improved coupling of chemical, mechanical, and hydrologic process descriptions• Improved understanding of permeability evolution due to concomitant geomechanical andgeochemical processesThese improvements will directly impact technical programs in carbon capture and geologicstorage by providing advanced simulation capabilities and reservoir management tools, improvedmonitoring and verification techniques, and new inputs, constraints, and methodologies forhazard and risk evaluation. More broadly, these improvements would significantly impact ourability to model and monitor shallow crustal deformation caused by other perturbations, bothnatural and engineered.Basic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems 139