The present work deals with the investigation of effects produced by carbon dioxide hydrate presence around a natural gas hydrate deposit. A laboratory scale reactor was performed to reproduce conditions feasible for hydrate formation. Six experimental tests were made. Firstly methane hydrate were formed and, then, temperature was increased to describe its relation with hydrate dissociation. In the second group of tests, after methane hydrate formation, carbon dioxide was injected, to form a hydrate shell around the present methane nucleus; then temperature was increased for generating hydrate dissociation. Finally a complete CO2 replacement process was carried out in the third group of tests. In case of only methane hydrate presence, the temperature increase caused an abundant pressure increase (due to water cages dissociation). The same temperature increase did not provoke any dissociation in presence of CO2 hydrate. In the third group of tests, the gas-chromatographic analysis of gas mixture, present inside hydrate after the CO2 replacement process completion, revealed a consistent presence of methane. Results clearly show how the presence of CO2 hydrate hinder the methane hydrate dissociation, even if the thermodynamic conditions are not suitable for their stability.
Effects of injecting gaseous CO2 on natural gas hydrate reservoirs: comparison of differences in clathrate dissociation behaviour.
Gambelli Alberto Maria;Filipponi Mirko;Rossi Federico
2019
Abstract
The present work deals with the investigation of effects produced by carbon dioxide hydrate presence around a natural gas hydrate deposit. A laboratory scale reactor was performed to reproduce conditions feasible for hydrate formation. Six experimental tests were made. Firstly methane hydrate were formed and, then, temperature was increased to describe its relation with hydrate dissociation. In the second group of tests, after methane hydrate formation, carbon dioxide was injected, to form a hydrate shell around the present methane nucleus; then temperature was increased for generating hydrate dissociation. Finally a complete CO2 replacement process was carried out in the third group of tests. In case of only methane hydrate presence, the temperature increase caused an abundant pressure increase (due to water cages dissociation). The same temperature increase did not provoke any dissociation in presence of CO2 hydrate. In the third group of tests, the gas-chromatographic analysis of gas mixture, present inside hydrate after the CO2 replacement process completion, revealed a consistent presence of methane. Results clearly show how the presence of CO2 hydrate hinder the methane hydrate dissociation, even if the thermodynamic conditions are not suitable for their stability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
