Raman Micro-Imaging of the Coexistence of sI and sII Hydrates Formed from a Mixed Methane-Propane Gas
in a Confined Space |
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| Authors: | CAI Wenjiu ZHAN Linsen HUANG Xin LU Hailong |
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| Institution: | 1 College of Engineering, Peking University, Beijing 100871, China
2 Beijing International Center for Gas Hydrate, School of Earth and Space Sciences, Peking University, Beijing 100871, China;3 SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China |
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| Abstract: | Natural gas hydrate contains a specific amount of heavy hydrocarbons, such as ethane, propane, etc., aside from the primary guest gas of methane. Although the coexistence of two or even three hydrate structures has been discovered at several hydrate sites, the requisite formation mechanism is still not well understood. In-situ observation of the formation process of mixed methane-propane hydrate in a confined space was conducted using confocal Raman imaging microscopy. The Raman imaging results reveal that sI methane hydrate and sII mixed methane-propane hydrate are formed and coexist in the reaction system. In the confined space, the sI hydrate originates from the dissolved gas in water, while the sII hydrate is formed from free gas. The results obtained can help explain the coexistence of sI and sII hydrates found in natural hydrate samples, as well as providing insights into a possible dynamic scenario of hydrate reservoirs in geological history. |
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| Keywords: | Raman imaging mixed hydrate coexistence sI hydrate sII hydrate |
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