X射线衍射分析聚乙烯吡咯烷酮对水合物分解过程的影响

The exploration and development of deep-water oil and gas resources and the environmental protection requirements in the mining process make the use of natural gas hydrate kinetic inhibitors inevitable. The research on the decomposition of kinetic inhibitors is of great guiding significance for the plug removal after hydrate formation. In this paper, a mixture of methane and propane was used to synthesize natural gas hydrates in a high-pressure reactor, and the decomposition process of hydrates containing the kinetic inhibitor polyvinylpyrrolidone was analyzed by an X-ray powder diffractometer. The results show that methane and propane gases will form SⅡ-type hydrates, but with the formation of SⅠ-type methane hydrates; after adding the kinetic inhibitor, the decomposition rate of hydrates slows down. At -60°C, after adding 0.5% polyvinylpyrrolidone, within the first 20 minutes of decomposition, the hydrate decomposition in the inhibitor-free system can reach 69%, while in the inhibitor-containing system it is about 18%; during the decomposition process of SⅡ-type methane-propane mixed gas hydrates, the decomposition rates of each crystal plane of the unit cell are the same, without preference, and the hydrate cage decomposes as a whole. Adding an inhibitor does not change this decomposition mode, and it still decomposes as a whole.

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。