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

APPENDIX 1: TECHNICAL PERSPECTIVES RESOURCE DOCUMENTsystem with many injection efforts. Displaced brines could potentially intrude into fresh wateraquifers up-dip or along high-transmissivity pathways. Operation of hundreds or even thousandsof wells in a larger region could result in unanticipated pressure interference and geomechanicalconcerns. Injection and production of large volumes of fluids into and out of producinggeothermal and oil and gas reservoirs has resulted in induced seismicity (Phillips et al. 2002).Although the risks of substantial induced seismicity appear small (e.g., Raleigh et al. 1976),similar effects are possible for large-scale CO 2 injection. Studies around a regional deploymenthave not yet provided answers to these and similar questions.TECHNOLOGY AND APPLIED RESEARCH AND DESIGN PERSPECTIVES ANDNEEDSAlthough much commercial oil-related technology exists for geological carbon sequestrationpilot efforts, there remain important scientific and technical challenges to large-scale commercialdeployment. These challenges can be summarized as being able to understand the complexgeology of any given site and how each of the geological variables will affect the performance ofa site. Sequestration of greenhouse gases from the atmosphere for substantial periods of time isrequired, but possibly perfect isolation or containment is not required. Sites must be able toaccept large volumes of CO 2 over many decades and then hold the overwhelming majority ofthat volume for many decades, possibly centuries or longer. They must do so without substantialoperational risk while maintaining health, safety, and environmental standards.The following set of technical needs flows from the goals of effective geological storage(Figure 5). The research and development needs are derived from the specific technical andscientific challenges associated with the central elements of site characterization, selection,operation, and monitoring.Site characterizationThe first stage in a project life cycle (Figure 5) is site characterization. Siting viable geologicalstorage projects requires substantial geological characterization prior to project deployment. Thedetail, degree of quantification, and precision of characterization will be driven by regulatory,legal and insurance requirements, and cost effectiveness. These needs and goals will change asthe project proceeds through different stages of operation and regulation. Initial sitecharacterization will focus on locations with low overall risk and high chance of success, shortandlong-term. It will provide data for planning, including safe and successful operations,deployment of monitoring and verification tools, and risk quantification and management.While many possible goals and terms may be pursued in site characterization, it is difficult toimagine the success of a large-scale injection project without knowledge of three parameters.These are injectivity, capacity, and effectiveness (Friedmann 2006). In general terms, injectivityand capacity may be estimated by conventional means, such as special core analysis, regionaland local structural and stratigraphic mapping, and simple multi-phase fluid flow simulations.However, there are few explicit standard measures of effectiveness. Ultimately, characterizationsmust rely on estimates of geomechanical integrity, hydrodynamic stability, and seal continuityfor the rock system, fault system, and well system (e.g., Hovorka et al. 2006). Some aspects ofeffectiveness characterization (e.g., continuity and thickness of cap-rock, presence of multipleseals, structural closure) may be easily defined with limited suites of data and analysis. OtherBasic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems Appendix 1 • 17