Numerical Simulation of CO2 Hydrate Formation in Lab-Scale Experiment

• Main Authors: MuhammadDahyar, 許聿學
• Other Authors: Bieng-Zih Hsieh
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/8c5dq6

碩士 === 國立成功大學 === 資源工程學系 === 106 === CO2 is a byproduct of burning fossil fuels and it is a gas that is notoriously associated with global warming, a concept that has had widespread effects on both human and environmental systems. Storing CO2 in solid hydrates are promising option for the long-term storage of CO2. The injection of CO2 into a hydrate layer may also replace CH4 as a guest molecule inside of an already-formed hydrate structure. This replacement reaction results in the release CH4 and the formation of CO2 hydrate. The formation rate of a hydrate is generally dependent upon the thermodynamic conditions. To obtain the optimal formation rate, this study was conducted to investigate the CO2 hydrate formation behavior in a laboratory setting. In this study, the STARS simulator developed by CMG Ltd. was used to build a reliable model of the CO2 hydrate reaction and predict the behavior of CO2 hydrate formation in a reservoir. This research was based on experiments used in previous research conducted by the team from the National Taiwan University of Science and Technology (NTUST). The numerical simulation was modeled identically to that of the former experiment and it used as a reference for the similarity of the results of pressure and temperature. Sensitive analysis was carried out to understand the parameters affecting the reaction. The investigated parameters included the absolute permeability, relative permeability, activation energy, enthalpy, thermal conductivity and heat capacity. This study was successful in establishing a CO2 hydrate model based on comparison with the results of experimentation. With the establishment of such a model, the following conclusions could be made: [1] rock and flow properties were the fundamental parameter which control hydrate formation, [2] the reaction parameters were the main parameter of the CO2 hydrate phase behavior which control the molecular exchange, and [3] the thermal properties of the porous medium did not greatly impact the hydrate formation. A directly proportional relationship between the hydrate concentration and average temperature distribution was determined to due the exothermic reactions that occurred at the boundary between the gas and the porous medium.