Model Components of the Certification Framework for Geologic Carbon Sequestration Risk Assessment

Abstract

Chapter 1 MODEL COMPONENTS OF THE CERTIFICATION FRAMEWORK FOR GEOLOGIC CARBON SEQUESTRATION RISK ASSESSMENT Curtis M. Oldenburg 1 , Steven L. Bryant 2 , Jean-Philippe Nicot 3 , Navanit Kumar 2,5 , Yingqi Zhang 1 , Preston Jordan 1 , Lehua Pan 1 , Patrick Granvold 4 , Fotini K. Chow 4 Earth Sciences Division, 90-1116, 1 Cyclotron Rd., Lawrence Berkeley National Laboratory, Berkeley CA 94720 Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, 1 University Station C0300, Austin, TX 78712 Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, University Station, Box X, Austin, Texas 78713 Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, CA 94720 Shell Oil and Production Company, 200 North Dairy Ashford, Houston, TX 77079 ABSTRACT: We have developed a framework for assessing the leakage risk of geologic carbon sequestration sites. This framework, known as the Certification Framework (CF), emphasizes wells and faults as the primary potential leakage conduits. Vulnerable resources are grouped into compartments, and impacts due to leakage are quantified by the leakage flux or concentrations that could potentially occur in compartments under various scenarios. The CF utilizes several model components to simulate leakage scenarios. One model component is a catalog of results of reservoir simulations that can be queried to estimate plume travel distances and times, rather than requiring CF users to run new reservoir simulations for each case. Other model components developed for the CF and described here include fault characterization using fault-population statistics; fault connection probability using fuzzy rules; well-flow modeling with a drift-flux model implemented in TOUGH2; and atmospheric dense-gas dispersion using a mesoscale weather prediction code. INTRODUCTION We have developed a novel and practical risk-based framework for certifying that the leakage risk of a potential geologic carbon sequestration (GCS) site is below agreed-upon thresholds [1, 2, 3]. The approach we developed, known as the Certification Framework (CF), proposes a standardized way for project proponents, regulators, and the public to analyze and understand risks and uncertainties of GCS in a simple and transparent way. The CF goes beyond the scope of regulations of deep underground injection permitted by the U.S. Environmental Protection Agency (EPA) which protect underground sources of drinking water (USDW) to consider risks to a broader set of resources and environmental assets as well as loss of emission-reduction credits due to CO 2 leakage. The CF uses physically grounded models for the movement of injected CO 2 and brine, and for assessing the likelihood that CO 2 or injection-related pressure perturbation will intersect wells and faults. The CF and an example case study have been fully described elsewhere [3]. This paper describes the essential model components that we have developed for carrying out a CF analysis. These model components include the catalog of simulation results, fault population statistics, fault connectivity analyses, well-bore flow, and dense gas dispersion.