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OS5C-5：EXPERIMENTAL STUDIES OF METHANE RECOVERY FROM METHANE HYDRATES BY A COMBINATION OF FLUE GAS INJECTION AND DEPRESSURISATION
发布时间:2014-07-28
Anthony OKWANANKE1， Jinhai YANG2, Bahman TOHIDI3
Centre for Gas Hydrates Research, Institute of Petroleum Engineering, Heriot-Watt University, UK
A novel technique for methane recovery from methane hydrate involving a combination of flue gas injection and depressurisation and its accompanying CO2 sequestration was studied. Test conditions (273.2K, 278K, 282K, and 284K) were chosen to cover the range of conditions obtainable in the gas hydrate stability zones (GHSZs) of naturally occurring natural gas hydrate reservoirs. Test results shows that methane recovery by flue gas injection and depressurisation was in three stages. The first two stages were by shift in methane hydrate equilibrium phase boundary. Recovery in the first stage was high and fast, occurring in the first five hour for all tests as the system adjusts to a new equilibrium due to fast methane hydrate decomposition. Recovery in the second stage was slow and became relatively constant as a new equilibrium is reached while recovery in the third stage was by depressurisation. Vapour phase CO2 concentration reduced as methane concentration increased in the first two stages but increased with increasing methane concentration in the third stage due to evolution of dissolved CO2 in water and decomposition of CO2-CH4 mixed hydrate and CO2 hydrate. CO2 hydrate decomposition indicates the formation and sequestration of CO2 as CO2 hydrate.
Centre for Gas Hydrates Research, Institute of Petroleum Engineering, Heriot-Watt University, UK
A novel technique for methane recovery from methane hydrate involving a combination of flue gas injection and depressurisation and its accompanying CO2 sequestration was studied. Test conditions (273.2K, 278K, 282K, and 284K) were chosen to cover the range of conditions obtainable in the gas hydrate stability zones (GHSZs) of naturally occurring natural gas hydrate reservoirs. Test results shows that methane recovery by flue gas injection and depressurisation was in three stages. The first two stages were by shift in methane hydrate equilibrium phase boundary. Recovery in the first stage was high and fast, occurring in the first five hour for all tests as the system adjusts to a new equilibrium due to fast methane hydrate decomposition. Recovery in the second stage was slow and became relatively constant as a new equilibrium is reached while recovery in the third stage was by depressurisation. Vapour phase CO2 concentration reduced as methane concentration increased in the first two stages but increased with increasing methane concentration in the third stage due to evolution of dissolved CO2 in water and decomposition of CO2-CH4 mixed hydrate and CO2 hydrate. CO2 hydrate decomposition indicates the formation and sequestration of CO2 as CO2 hydrate.
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