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

APPENDIX 1: TECHNICAL PERSPECTIVES RESOURCE DOCUMENTand gas applications, this uncertainty is neither characterized initially nor propagated throughsuccessive elements of work flows because it is not critical to current operations. New datacommonly are not integrated with prior data in a fashion as to reduce or manage the initialuncertainty. Various approaches, including stochastic inversion (Ramirez et al. 2005) providetools and approaches to address this task; however, they require large computational resourcesand expert capability, and have not been broadly applied to common subsurface operations.Improved technology development and deployment in uncertainty rendering and managementwould dramatically improve the accuracy of site-specific work and the ability of operators toselect monitoring and characterization tools that would reduce uncertainty.Fracture systems and geomechanicsFracture networks may be critical components to geological carbon sequestration targets forseveral reasons:1. They can play a substantial, sometimes dominant, role in the hydrological flow field2. They can represent potential migration fast paths through cap-rocks and along fault networks3. Their transmissivity may be dynamic, responding to both pressure transients and chemicaldisequilibriaThe response of existing fracture networks to pressure and stress transients are of specialimportance in saline formations where the pre-injection pressure is likely to be hydrostatic. Inaddition, overpressures generated by the CO 2 injections may generate new local fracture systemswith different properties. In unmineable coal units, the rock volumes swell in the presence ofCO 2 , closing fractures (cleats) and dramatically reducing injectivity. Fracture orientation anddensity have been successfully inferred from observations of seismic anisotropy from shearwavesplitting (e.g., Li 1997), but seismic characterization of fracture permeability remains a keyresearch objective for the oil and gas industry. In rendering fracture networks and their processresponse, substantial uncertainties remain in fracture orientation, length, transmissivity, andresponse to stress.Mineral chemical kineticsMineral carbonation has been regularly observed in natural analog systems, and laboratoryexperiments provide thermodynamic and kinetic constraints for some key minerals or mineralassemblages. These constraints greatly impact the accuracy and precision of complex reservoirsimulations (e.g., Johnson et al. 2005). At least three important technical needs remain:1. A more comprehensive suite of kinetic and equation-of-state data sets, particularly aimed atthe small fraction of the rock volume with rapid reaction kinetics (e.g., metal oxides andhydroxides; Kharaka et al. 2006)2. An improved theoretical and experimental basis for determining the reactive surface areawithin a rock3. The effects of trace (co-contaminant) gases on phase equilibria and kineticsSimulation and modelingShort- and long-term modeling is central to many aspects of planning, operational control,analysis, risk assessment, and site decommissioning. At present, simulation and modeling are theprimary tools for providing qualitative or quantitative assessments of the long-term fate of CO 2Appendix 1 • 22Basic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems