Physical property research of CO2 in Yan Chang Oilfield pipeline transportation

Abstract

The capture, utilization and storage (CCUS) of CO2 has become a hot topic in the current environmental protection field. What's more, CO2 gas sources contain various impurities, which may have a great influence on the physical properties of CO2. So understanding the physical and chemical properties of CO2 with impurities as well as the differences of between it and pure CO2, is the basis of carrying out pipeline technology for transporting CO2. By comparing the various equations of state, we choose PR equation to calculate the phase state and physical properties of CO2 containing impurities. In addition, we have used HYSYS software conduct research on 30 MT/a CO2 with impurities of Yan Chang Oilfield. The study shows that its critical point is T=30.37°C, P=7.55MPa. Compared with the pure CO2, its critical temperature reduces, critical pressure rises, and there is a two-phase region in the phase diagram, which indicates that the existence of impurities makes it harder to convey CO2 in the pipeline. In the vicinity of critical point, tiny changes from pressure and temperature will make its density, viscosity, thermal conductivity and compression coefficient vary in a large range. Currently, China hasn't established long-distance pipeline to transport CO2, and we also lack the experience of conveying CO2 with impurities in pipeline. However, the physical properties of CO2 containing impurities is primary problem to solve in the pipeline transportation. This paper supplies some its physical properties, which is the fundamental work of developing pipeline transportation for CO2.