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

PANEL REPORT: MULTIPHASE FLUID TRANSPORT IN GEOLOGIC MEDIAspace filled with a nonwetting fluid will provide more reliable inventories of hydrocarbonreserves and the mass of stored CO 2 in the subsurface.Theoretical foundations for high-resolution spatial and temporal imaging of multiphase fluiddistributionsIdentification of local properties from global measurements is the key challenge for highresolutiongeophysical imaging. This requires consideration of both the spatial and temporalscale of the global measurements, as well as the local properties of interest. The inherent multiscale,multiphysics nature of this problem requires development of new theoretical approachesthat preserve and reveal the relevant underlying physics, while volume averaging materialproperties over a spatial scale that is consistent with the resolution of the measurement.Limitations of current theoretical approaches will require inclusion of more comprehensivephysical descriptions of wave interactions with the complex multiphase systems. For example,serious limitations in our current ability to image the spatial distribution of multiple fluid phasesin rocks using seismic imaging can be overcome by moving beyond velocity-based tomographyto methods that include wave attenuation and/or make use of the full wave form generated by theseismic source. Fundamental new understanding will be needed to develop the foundation fornext-generation imaging approaches.Constitutive relationships among waves, fields, and properties of multiphase flow systemsA comprehensive sequence of laboratory measurements at a variety of spatial scales is needed toestablish a rich database to study the effects of fluids on bulk geophysical and flow properties.Examples include seismic compressibility, velocity, attenuation, electrical resistivity, dielectricconstant, density, and saturation. These measurements, along with associated theoretical models,provide a robust scientific basis for relating geophysical measurements such as seismic velocityand attenuation to the amount and spatial distribution of fluid phases in the subsurface.Coupled models for flow dynamics and imagingThis challenging problem requires development of integrated models that account for waves,potential fields, and flow and transport in porous media. Traditionally, each of thesesubdisciplines has proceeded in isolation, passing primarily abstractions of concepts and resultsfrom one group to the next. Progress in quantitative high-resolution imaging will require removalof disciplinary barriers, leading to rigorous cross-fertilization among subdisciplines by creatingcommon theoretical and computational platforms. To this end, one must consider theoretical,mathematical and experimental (laboratory) activities that, in concert, seek to understand andquantify the relationships and sensitivities of image parameters to multiphase flow parameters ofinterest.Large computational domainsComputational requirements for forward simulations and inverse models motivate thedevelopment of new computing paradigms, both algorithms and computer architectures.However, these new paradigms must carefully consider tradeoffs between capturing the relevantmodel descriptions and the computational loads. That is, new algorithms and architectures mustconsider the needs of the applications on a basis equal to the way applications have consideredBasic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems 21