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题名	化学剂作用下气体水合物分解特性研究; Study on Dissociation Features of Gas Hydrate In the Presence of Chemicals
作者	万丽华
学位类别	博士
答辩日期	2009-01-05
授予单位	中国科学院广州能源研究所
授予地点	广州能源研究所
导师	李小森
关键词	气体水合物 开采 分解 分子动力学模拟 过氧化氢溶液 热力学抑制剂
其他题名	Study on Dissociation Features of Gas Hydrate In the Presence of Chemicals
中文摘要	Among the recovery methods of natural gas production from hydrate reservoir, the thermal stimulation is safely and effectively capable of producing substantial amounts of natural gas, and it will be more effective combining with the chemical injection. The work investigates the dissociation behavior of methane hydrates in a one-dimensional experimental apparatus under hot brine (NaCl solution) stimulation. The results showed that the process of methane hydrate dissociation accompanied the temperature decrease and endothermal change with the injection of NaCl solution. The duration of the hydrate dissociation is shortened and the degree of the temperature drop increases with the increase of the brine concentration. In addition, the characteristics of the dissociated gas and water from methane hydrates in the porous sediment under hot brine stimulation were also investigated. The experimental results showed that the gas production process can be generally divided into three stages: free gas production, hydrate dissociation and general gas reservoir production. The rate of hydrates dissociation can be enhanced by the addition of NaCl. In the stage of free gas production, there was little water production. In the stage of hydrate dissociation, the rate of water production is slightly higher than that of water injection. In the final stage, the dissociation of hydrate has completed, and the rate of water production is equal to that of water injection.Thermal efficiency and energy ratio for the hydrate production can be enhanced by injecting hot brine solution, and the enhance effectiveness is quite good with the injection of high brine concentration at the relative low temperature. In order to investigate the novel natural gas hydrate production method involving methane hydrate deposits dissociation in-situ originated from gas oxygenation by hydrogen peroxide as an oxidizer to enhance the recovery efficiency, first of all, it was determined whether hydrogen peroxide forms hydrate as a former of structure I at elevated pressures in this work, that is, the stabilities of gas hydrate with structure I for hydrogen peroxide and mixture of methane and hydrogen peroxide at 277K were studied using NVT molecular dynamics simulations. The results show that the investigated hydrates can not be stably in existence,thus making it that hydrogen peroxide can not take part in clathrate formation.Then, the characteristics of the decomposition of methane hydrate in the presence of hydrogen peroxide solution were investigated using the molecular dynamics simulation. The mechanism of the transformation process from the solid hydrate to the liquid was analyzed with the effect of hydrogen peroxide (HP) solution. In addition, the effect of ethylene glycol (EG) with the same molar concentration with HP on the methane hydrate dissociation was also studied. It is deduced that hydrogen peroxide is potentially thermal inhibitor of hydrates from hydrogen peroxide promoting well the hydrate dissociation and not taking part in clathrate formation. However, to confirm this hypothesis, direct measurements of the hydrate phase are needed, i.e., by phase equilibrium experiment of hydrate forming from hydrogen peroxide solution. The dissociation of methane hydrates in the presence of ethylene glycol of 11.45 mol•L-l at 277.0 K was studied using NVT molecular dynamics simulations. The results showed that in the process of the hydrate dissociation, the distortion of the lattice structure of hydrate occurs firstly, and then it is evolved from fractured frame to fractional fragment. Finally, water molecule involving in the hydrate construction exists in the form of liquid state. In addition, the dissociating layer inside has been coated by the liquid film formed from dissociated water molecules outside. This film makes mass transfer performance of the molecules inside poor during the process of the hydrate dissociation.
语种	中文
公开日期	2011-07-14 ; 2011-07-15
页码	109
内容类型	学位论文
源URL	[http://ir.giec.ac.cn/handle/344007/5826]
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	万丽华. 化学剂作用下气体水合物分解特性研究, Study on Dissociation Features of Gas Hydrate In the Presence of Chemicals[D]. 广州能源研究所. 中国科学院广州能源研究所. 2009.

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