作　　者： ; ; ;

机构地区： 中国地质大学

出　　处： 《地球化学》 2005年第2期187-192,共6页

摘　　要： 水合物形成于相对低温高压环境,这种条件下对水合物形成后的流体中残留的甲烷浓度进行直接的原位观测非常困难。本文在高压透明腔体中成功合成了甲烷水合物,利用拉曼光谱技术在低温高压条件下对水合物形成过程中流体中残留的甲烷浓度的变化进行了原位观测,用拉曼峰面积比值法获得了三个温度、压力下水合物形成后的饱和甲烷浓度值。研究发现,水合物生长过程中,流体中的甲烷被不断消耗而浓度逐渐降低,温度对水合物形成后的流体中残留的饱和甲烷浓度影响很大,温度越低,残留的饱和甲烷浓度越小,与通常条件下甲烷在水中的溶解度随温度的降低而增加的趋势正好相反。 The knowledge of methane solubility in the hydrate stability zone is a key to understanding of the processes of kinetics of hydrate formation and the dynamic accumulation of marine hydrate deposits.However,little experiments were done to obtain such information due to the difficulty of measurement since hydrates are only stable at low temperature and high pressure condition,and until recent years,t he saturated concentration of methane in water are measured using sampling me thods at relative low pressures and r elative low temperatures.At presen t,no data is covering the temperatures ab ove 7℃or the pressure above 20MPa,an d no in situ measurements are made.In this study a new method is developed to in situ observe the variation of methane con centration in the liquid phase in present of hydrates and without fr ee gas phase at high pressures up to 47MPa.Methane hydrates are synthesiz ed in a high pressure capillary cell,an d Raman spectroscopy is used to monitor the variation of the methane concentration in the aqueous solution under high pressures during the growth of methane hydrates,as the concentration of methane in water co uld be calculated with peak area ratio method.It is found that the methane in the aqueous solution is consumed and the methane concentration in the aqueous solution deceasing with time when hydrate is growing and at last trends to keep constant after about 2days,i ndicating the equilibrium of the system is reached.The saturated concentrati ons are determined at 3temperatures and pressures.Our measurements of methane saturated concentration in the presence of hydrates are well agree with the results derived from the minimum in free energy and the trend i s consist with those obtained by Yang et al .(2001)by sampling method,indicating that this new in situ method is suitable for the study of ki netics of hydrate formation and dissolution in the absence of free gas.

关 键 词： 甲烷 水合物 拉曼光谱 溶解度

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