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

Abstract

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.