Abstract:

Injecting kinetic hydrate inhibitors is an effective method to prevent the blockage of natural gas hydrate pipelines. In this paper, based on the structure of polyvinyl caprolactam (PVCap), oxyethyl and ester groups are introduced into the molecular chain end of PVCap to synthesize a new kinetic hydrate inhibitor PVCap-XA1. The inhibition performance of PVCap-XA1 on the formation of methane hydrate was evaluated in a high-pressure constant-volume cell, and the effects of PVCap-XA1 on the structure and morphology of methane hydrate were studied by powder X-ray diffraction, Raman spectroscopy and scanning electron microscopy (Cryo-SEM). The results showed that PVCap-XA1 had better inhibition than PVCap under the same experimental conditions. Microscopic tests showed that the addition of PVCap-XA1 did not change the crystal structure of methane hydrate, but distort the crystal plane of methane hydrate, and reduced the ratio of I_L/I_S. Meanwhile, the addition of PVCap-XA1 makes the microscopic morphology of methane hydrate change from porous and orderly to denser, which was not conducive to the passage of gas.

Key words: natural gas hydrate, methane, kinetic inhibitor, modification, inhibition performance, morphology

摘要：

注入动力学抑制剂是一种有效缓解天然气水合物管道堵塞的方法。本文以动力学抑制剂聚乙烯基己内酰胺(PVCap)结构为基础，将氧乙基和酯基引入PVCap的分子链端，合成了新抑制剂PVCap-XA1，在高压定容反应釜内评价了PVCap-XA1对甲烷水合物形成的抑制作用，并采用粉末X射线衍射、低温激光拉曼光谱和冷冻扫描电子显微镜研究了抑制剂对甲烷水合物结构和形态的影响。实验结果表明，相同实验条件下PVCap-XA1比PVCap具有更好的抑制作用；微观测试表明PVCap-XA1的加入没有改变甲烷水合物的晶体结构，但会使甲烷水合物晶面扭曲变形，可以降低水合物大小笼占有比(I_L/I_S)，使得甲烷分子更难进入水合物大笼，同时PVCap-XA1的加入使甲烷水合物的微观形貌由多孔有序变得更致密而不利于气体通过。

关键词: 天然气水合物, 甲烷, 动力学抑制剂, 改性, 抑制能力, 形貌