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

GRAND CHALLENGE: SIMULATION OF MULTISCALE GEOLOGIC SYSTEMS FOR ULTRA-LONG TIMESpotentially leading to simplifications in predictive modeling. The prospect exists for discovery ofa new set of simpler models applicable to very long time and length scales appropriate to basinscaleinvestigations of CO 2 trapping and migration.The onset and form of density-driven flows in CO 2 storage reservoirs at all scales are controlledby the interplay between fluid dynamics and heterogeneity. Multiphase effects in the formerfurther complicate the processes as interfacial forces come into play. Through improvedunderstanding, better models of density-driven flows will be developed that are applicable to awide range of hydrogeologic problems beyond CO 2 storage.New conceptual models of multiscale flow will likely involve Navier-Stokes equationdescriptions of viscous flow in the pores coupled with Darcy formulations for larger scales. Theresulting seamless mathematical description of reactive flow over the full range of scalesrelevant to CO 2 storage systems will provide a scientific basis for developing process modelsappropriate for whatever length and time scales are of interest.Advanced modeling capabilities that can accurately describe multiscale processes will have thefollowing scientific impacts:• Improved understanding of the fundamental physics of flow and transport in geologicsystems• Reliable long-term simulations and predictions across multiple spatial and temporal scaleswith uncertainty quantification• Stimulating advances in computational and numerical methods for multiscale dynamics, dataintegration, system identification, and optimization• Deeper understanding of the dynamics of multiscale, multiphysics stochastic systems• Increased integration between data acquisition and modelingTECHNOLOGY IMPACTSThe desired product is the next generation of reactive transport simulators that explicitly accountfor the influence of multiscale physical and compositional heterogeneity on multiphase flow andchemical mass transfer processes, and are capable of forecasting the long-term isolationperformance of geologic storage over the broad range of compositional, hydrological, andstructural parameters that characterize proposed disposal sites. Explicit inclusion of multiscaleheterogeneity in key physical properties (e.g., porosity, permeability) will significantly improveforecasting of CO 2 or nuclear waste plume migration, which defines the spatial framework ofresidual-phase and geochemical trapping mechanisms. Analogous inclusion of multiscalecompositional heterogeneity will permit more accurate prediction of geochemical trappingmechanisms as well as related porosity/permeability evolution. Improved forecasting of plumemigration will enable more accurate prediction of aqueous migration paths and their evolution,which is required to predict reservoir/seal responses.Because the advanced reactive transport simulation capabilities outlined above provide improvedpredictions of CO 2 plume migration and trapping, brine displacement, and pressure evolution,they also provide tools for designing injection strategies, monitoring programs, and remediationtechniques—as well as for quantifying the uncertainties that bound such predictive and designBasic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems 103