天然流体包裹体中甲烷水合物生成条件原位变温拉曼光谱研究

准确获取流体包裹体中气体水合物的生成条件一直是传统包裹体分析方法面临的一个难题。文章采用原位拉曼光谱技术分析了天然流体包裹体中甲烷水合物的生成条件。并由常温拉曼光谱分析表明，研究流体包裹体的流体组成为CH4-H2O体系。通过三种方法控制实验温度的变化，在第三种方法实验条件下获得了-170 ℃时甲烷水合物与冰的拉曼光谱，逐渐升温原位观测甲烷水合物的消失温度。原位拉曼光谱检测结果表明，研究包裹体中甲烷水合物的生成温度为7.5 ℃。结合CH4-H2O体系水合物形成条件相平衡计算，得到包裹体中甲烷水合物生成时的压力为5.587 3 MPa。研究结果表明，原位拉曼光谱技术是准确获取流体包裹体种气体水合物生成条件的一种有效方法。

In situ Temperature-Dependent Raman Spectroscopic Studies on Methane Hydrate Forming in Natural Fluid Inclusion

It is always a difficult problem to accurately identify the formation condition of gas hydrates in fluid inclusions in conventional ways. The present paper introduces a new method to get the formation condition of methane hydrate in natural fluid inclusion by in situ Raman spectroscopy. The researched fluid inclusion is in a CH4-H2O system identified by Raman spectroscopy at room temperature. In order to obtain the Raman spectra of methane hydrate,the experimental temperature was controlled in three ways,and the Raman spectra of methane hydrate and ice were obtained at -170 ℃ in the third way. The results of in situ Raman spectroscopy show that the temperature of methane hydrate forming in the authors’ interested inclusion is 7.5 ℃. According to the equilibrium between water and methane hydrate in the CH4-H2O system,the authors’ computed the pressure for the methane hydrate formation to be 5.587 3 MPa. The authors study shows that the in situ Raman spectroscopy is an effective method to obtain the formation condition of gas hydrates in fluid inclusions.