Analysis of factors affecting the formation characteristics of carbon dioxide hydrates in pure water system

As the oilfield fully enters the late stage of exploitation, the water content in the oil and gas transportation pipelines is rising. Meanwhile, the high-pressure and low-temperature environment inside the pipeline facilitate the formation of hydrates, which will seriously block the mixing pipeline and cause a series of production safety problems. Therefore, it is necessary to control the risk under the high water content system. In this paper, a high-pressure flow loop device with a viewable window was used to study the formation characteristics of carbon dioxide hydrate in a pure water system, and the effects of the liquid loading, pressure, volume flow rate, and two inhibitors, polyvinylpyrrolidone (PVP) and propylene glycol methyl ether (PM), on the induction time of carbon dioxide hydrate formation were investigated. The experimental results showed that the amount of liquid loading, pressure, volume flow rate, and inhibitor had a significant effect on the hydrate induction time. In addition, the ether compounds PM and PVP have inhibitory synergistic effects, which can significantly prolong the hydrate induction time, and the inhibitory synergistic effect is further enhanced with the increase of PM concentration, which further suggests the synergistic inhibition mechanism of the two. Based on the standard regression coefficient method, the factors affecting the induction time were subjected to sensitivity analysis, and it was found that the inhibitor was the most important factor affecting the induction time. Therefore, future research should also focus on finding better performance of inhibitors, synergists and their ratio.

随着油田全面进入开发后期，油气输送管道内的含水率持续攀升。与此同时，管道内部的高压低温环境会加速水合物生成，这将严重堵塞混输管道，引发一系列生产安全问题，因此亟需在高含水体系下对该风险实施管控。本文采用搭载可视化窗口的高压流动环路装置，开展纯水系中二氧化碳水合物的生成特性研究，并系统考察了液相持液量、压力、体积流量，以及两种抑制剂——聚乙烯吡咯烷酮（polyvinylpyrrolidone，PVP）与丙二醇甲醚（propylene glycol methyl ether，PM）——对二氧化碳水合物生成诱导时间的影响。实验结果显示，液相持液量、压力、体积流量与抑制剂类型均对水合物诱导时间存在显著影响。此外，醚类化合物PM与PVP具备协同抑制效应，可显著延长水合物诱导时间，且该协同抑制效果随PM浓度升高进一步增强，这进一步佐证了二者的协同抑制机理。基于标准回归系数法，本文对影响诱导时间的各因素开展敏感性分析，结果表明抑制剂是影响诱导时间的最核心因素。因此，未来研究应进一步聚焦于开发性能更优异的抑制剂、协效剂及其最优配比。