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

PRIORITY RESEARCH DIRECTION:FLUID-INDUCED ROCK DEFORMATIONFigure 45. Example of nonlinear, history-dependent property response to pressure. Left: Measured changes in rockelastic modulii as a function of microfracture density under different pressure cycles. Right: Mohr-circlerepresentation of associated stress rotations and failure envelopes. From Faulkner et al. 2006; reprinted bypermission from Macmillan Publishers Ltd: Nature 444, 922-925 (2006).RESEARCH APPROACHESNew scientific insight and advanced simulation capabilities can be achieved through a set ofcomplementary technical approaches that span the range of relevant length scales. The ultimategoal of this integrated research area is to develop coupled field-scale models that fully capturethe fundamental physical and chemical processes. The research will be is grounded byexperimental laboratory studies designed to constrain the fundamental processes that control therheological behavior of fluid-rock systems. Recent advances in X-ray computed tomographicimaging and enhanced spectroscopic techniques applied to cores under reservoir conditions canprovide new data to constrain the evolution of perturbed fluid-rock systems. The laboratory workwill help design field studies of geomechanical processes where innovativegeophysical/hydrological techniques can be used to monitor the integrated system response tocommercial-scale CO 2 injection over the relevant range of geologic settings. Building upon andconstrained by the laboratory experiments and field studies, fundamentally new modelingapproaches must be developed that effectively represent coupled mechanical, chemical, andhydraulic processes in deformable, brittle media. Both discrete and continuum modelingapproaches may be applied to these problems, but the ultimate objective of either approach is toexplicitly represent process coupling over the full range of length scales. These models willrequire improved constitutive relationships or upscaling techniques for representing coupledprocesses from the pore scale to the field scale.SCIENTIFIC IMPACTSNew experimental results, field data, and process coupling techniques will lead to the emergenceof novel mathematical and computational approaches for representing and simulating fullyintegrated geomechanical and multiphase flow processes. These advanced simulation capabilitieswill permit more accurate long-term forecasting of injection-induced geomechanical effects thatrange from poroelastic deformation to dynamic fracturing over the full range of length scales thatcharacterize multiphase-fluid saturated reservoir/cap-rock/well-bore systems. Moreover, thedevelopment of improved mathematical formulations and computational techniques for142 Basic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems