Maximizing Storage Rate and Capacity and Insuring the Environmental Integrity of Carbon Dioxide Sequestration in Geological Reservoirs

Abstract

Maximizing Storage Rate and Capacity and Insuring the Environmental Integrity of Carbon Dioxide Sequestration in Geological FormationsThe U.S. and other countries may enter into an agreement that will require a significant reduction in CO 2 emissions in the medium to long term. In order to achieve such goals without drastic reductions in fossil fuel usage, CO 2 must be removed from the atmosphere and be stored in acceptable reservoirs. The research outlined in this proposal deals with developing a methodology to determine the suitability of a particular geologic formation for the long-term storage of CO 2 and technologies for the economical transfer and storage of CO 2 in these formations. A novel well-logging technique using nuclear-magnetic resonance (NMR) will be developed to characterize the geologic formation including the integrity and quality of the reservoir seal (cap rock). Well-logging using NMR does not require coring, and hence, can be performed much more quickly and efficiently. The key element in the economical transfer and storage of the CO 2 is hydraulic fracturing the formation to achieve greater lateral spreads and higher throughputs of CO 2 . Transport, compression, and drilling represent the main costs in CO 2 sequestration. The combination of well-logging and hydraulic fracturing has the potential of minimizing these costs. It is possible through hydraulic fracturing to reduce the number of injection wells by an order of magnitude.Many issues will be addressed as part of the proposed research to maximize the storage rate and capacity and insure the environmental integrity of CO 2 sequestration in geological formations. First, correlations between formation properties and NMR relaxation times will be firmly established. A detailed experimental program will be conducted to determine these correlations. Second, improved hydraulic fracturing models will be developed which are suitable for CO 2 sequestration as opposed to enhanced oil recovery (EOR). Although models that simulate the fracturing process exist, they can be significantly improved by extending the models to account for nonsymmetric, nonplanar fractures, coupling the models to more realistic reservoir simulators, and implementing advanced multiphase flow models for the transport of proppant. Third, it may be possible to deviate from current hydraulic fracturing technology by using different proppants (possibly waste materials that need to be disposed of, e.g., asbestos) combined with different hydraulic fracturing carrier fluids (possibly supercritical CO 2 itself). Because current technology is mainly aimed at enhanced oil recovery, it may not be ideally suited for the injection and storage of CO 2 . Finally, advanced concepts such as increasing the injectivity of the fractured geologic formations through acidization with carbonated water will be investigated. Saline formations are located through most of the continental United States. Generally, where saline formations are scarce, oil and gas reservoirs and coal beds abound...