Gajbhiye Rahul
King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
ACS Omega. 2020 Oct 21;5(43):27944-27952. doi: 10.1021/acsomega.0c03326. eCollection 2020 Nov 3.
CO-enhanced oil recovery (EOR) has demonstrated significant success over the last decades; it is one of the fastest-growing EOR techniques in the USA accounting for nearly 6% of oil production. A large quantity of CO gas is required for the EOR process and sometimes other gases such as hydrocarbons, air, flue gases, CO, N, and mixtures of two or more gases are used for injection. It is also realized that the injection of CO and N combines advantage in reducing CO concentrations in the atmosphere and improving the oil recovery by sequestering it underground. However, there are a number of variables involved in the successful design of the CO-EOR process. The objective of this study is to investigate the effect of CO/N mixture composition on interfacial tension (IFT) of crude oil. Experiments were performed to measure the IFT of the CO/N mixtures and crude oil for different compositions of gas by varying the system pressure at a fixed temperature. The effect of CO/N mixture composition and pressure on the IFT of crude oil is evaluated. The experimental results show that an increase in the mole fraction of CO in the gas mixture results in a decrease in IFT between CO-oil, irrespective of the system pressure. However, because of an increase in the mole fraction of N in the gas mixture, an increase in IFT was observed and this change is opposite to the effect of the CO mole fraction. Also, the change in IFT is consistent with the pressure, which means that the IFT decreases with an increase in the pressure at a given temperature. The effect of the CO mole fraction is more profound compared to the N fraction and with the pressure at which experiments were conducted in this study. The finding of this study helps in designing the CO-EOR process in which achieving miscibility conditions is vital for taking advantage of the CO injection. Also, the presence of N and its influence on the IFT that must be considered in the CO-EOR were addressed in this study.
在过去几十年中，二氧化碳强化采油（EOR）已取得显著成功；它是美国发展最快的强化采油技术之一，占石油产量近6%。EOR过程需要大量的二氧化碳气体，有时也会使用其他气体进行注入，如碳氢化合物、空气、烟道气、一氧化碳、氮气以及两种或更多种气体的混合物。人们还认识到，注入二氧化碳和氮气具有双重优势，既能降低大气中的二氧化碳浓度，又能通过将其封存于地下提高石油采收率。然而，成功设计二氧化碳强化采油工艺涉及多个变量。本研究的目的是探究二氧化碳/氮气混合物组成对原油界面张力（IFT）的影响。通过在固定温度下改变系统压力，对不同气体组成的二氧化碳/氮气混合物与原油的界面张力进行了测量实验。评估了二氧化碳/氮气混合物组成和压力对原油界面张力的影响。实验结果表明，无论系统压力如何，气体混合物中二氧化碳摩尔分数的增加都会导致二氧化碳与原油之间的界面张力降低。然而，由于气体混合物中氮气摩尔分数的增加，观察到界面张力升高，且这种变化与二氧化碳摩尔分数的影响相反。此外，界面张力的变化与压力一致，即在给定温度下，界面张力随压力升高而降低。与氮气分数以及本研究进行实验时的压力相比，二氧化碳摩尔分数的影响更为显著。本研究结果有助于设计二氧化碳强化采油工艺，在该工艺中，实现混相条件对于利用二氧化碳注入至关重要。此外，本研究还探讨了氮气的存在及其对二氧化碳强化采油中界面张力的影响，这一点在工艺设计中必须予以考虑。
