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

GRAND CHALLENGE:INTEGRATED CHARACTERIZATION, MODELING, AND MONITORING OF GEOLOGIC SYSTEMSCourtesy of Sally Benson, Stanford University, and Andy Chadwick, British Geological SurveyFigure 31. Example of the varied approaches used to measure geochemical-geophysical-hydrological subsurfaceproperties and processes, modified from David and Elewaut (2006) and Benson and Hepple (2005), and withmeasurement approaches from Chadwick (British Geological Survey).we are at a threshold in developing such geophysical monitoring approaches. An example of theuse of time-lapse seismic crosshole data with petrophysical relationships to estimate the CO 2saturation associated with the Frio brine CO 2 injection pilot test is shown in Figure 32. For thepurpose of monitoring CO 2 , it is vital to be able to detect small amounts of leakage (Wells et al.2006). For example, leakage of only 0.5% per year over 200 years leads to a loss of 66%.Monitoring must be sufficiently sensitive and cover sufficient volumes of the subsurface todetect such small leakage.Because anthropogenic manipulations often result in complex flow-reactivity responses, andgeophysical attributes can be sensitive to various properties, the use of multiple methods cangreatly reduce uncertainty associated with the use of geophysical datasets to quantitativelymonitor system transformations. Figure 33 illustrates the use of time-lapse geophysical datasetsto provide quantitative, time-lapse estimates of biogeochemical transformations associated with amanipulation experiment in the laboratory. Although these recent studies illustrate the potential86 Basic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems