Abstract:

With the exploration and development of deepwater oil and gas resources and the environmental protection requirements, the use of gas hydrate kinetic inhibitors is inevitable. So the study of gas hydrate decomposition containing kinetic inhibitors has important guiding significance for the plug removal after hydrate formation. In this paper, a mixture of methane and propane is used in the high-pressure reactor to form natural gas hydrate, and the hydrate decomposition process containing kinetic inhibitor polyvinglpyrrolidone is analyzed by X-ray powder crystal diffractometer. The results showed that methane and propane can form SⅡ gas hydrates, but there still exists some SⅠ methane hydrates. After the addition of kinetic inhibitors, the decomposition rate of hydrate slowed down. At -60℃, in the first 20 min, 69% hydrate decomposed in the non-inhibitor system, about 18% in the system with 0.5% polyvinylpyrrolidone. During dissociation process of CH₄-C₃H₈ SⅡ hydrates, crystal planes decomposition rate of hydrate cell is the same and there is no preferential rate of dissociation of either planes with or without polyvinylpyrrolidone, which implies that the unit cell decomposes as a single entity. Kinetic inhibitor polyvinylpyrrolidone cannot change this decomposition way.

Key words: natural gas hydrates, kinetic inhibitors, dissociation, X-ray diffraction, crystal structure

摘要：

深水油气资源的勘探开发以及开采过程中的环保要求，使得天然气水合物动力学抑制剂使用不可避免，含动力学抑制剂的分解研究对水合物生成后的解堵具有重要的指导意义。本文在高压反应釜内采用甲烷和丙烷混合气，合成天然气水合物，并用X射线粉晶衍射仪分析了含动力学抑制剂聚乙烯吡咯烷酮的水合物分解过程。结果显示甲烷和丙烷气体会形成SⅡ型水合物，但伴随有SⅠ型甲烷水合物的生成；添加动力学抑制剂后，水合物的分解速率变慢，在-60℃，添加0.5%的聚乙烯吡咯烷酮后，分解起始的20 min内，无抑制剂体系水合物分解可达69%，而在含抑制剂体系分解约18%；SⅡ型甲烷丙烷混合气水合物分解过程中晶胞各晶面分解速率相同，没有偏好性，水合物笼作为一个整体分解，添加抑制剂不改变这种分解方式，仍以整体分解。

关键词: 天然气水合物, 动力学抑制剂, 分解, X射线衍射, 晶体结构