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Languages : en
Pages : 8
Book Description
Natural gas reservoirs are obvious targets for carbon sequestration by direct carbon dioxide (CO2) injection by virtue of their proven record of gas production and integrity against gas escape. Carbon sequestration in depleted natural gas reservoirs can be coupled with enhanced gas production by injecting CO2 into the reservoir as it is being produced, a process called Carbon Sequestration with Enhanced Gas Recovery (CSEGR). In this process, supercritical CO2 is injected deep in the reservoir while methane (CH4) is produced at wells some distance away. The active injection of CO2 causes repressurization and CH4 displacement to allow the control and enhancement of gas recovery relative to water-drive or depletion-drive reservoir operations. Carbon dioxide undergoes a large change in density as CO2 gas passes through the critical pressure at temperatures near the critical temperature. This feature makes CO2 a potentially effective cushion gas for gas storage reservoirs. Thus at the end of the CSEGR process when the reservoir is filled with CO2, additional benefit of the reservoir may be obtained through its operation as a natural gas storage reservoir. In this paper, we present discussion and simulation results from TOUGH2/EOS7C of gas mixture property prediction, gas injection, repressurization, migration, and mixing processes that occur in gas reservoirs under active CO2 injection.
