Reducing the minimum miscibility pressure of CO2 and crude oil using alcohols

The establishment of a miscible phase between CO 2 and crude oil can significantly improve CO 2 flooding efficiency. However, the minimum miscibility pressure (MMP) between CO 2 and crude oil is usually higher than the fracture pressure of the formation, how to reduce the MMP between CO 2 and crude oil is very important, and there are fewer related studies. Our inspiration for reducing MMP comes from the unique dispersion characteristics of CO 2 in alcohol, the intermolecular force of crude oil may decrease due to the existence of alcohols. In this paper, the CO 2 solubility and the oil volume expansion with adding a variety of alcohols (1-butanol, 1-pentanol and 1-hexanol) were measured by a visible high temperature and high pressure cell from 7 MPa to 20 MPa at 343.15 K. The MMP between CO 2 and crude oil is predicted by measuring the interfacial tension (IFT) between CO 2 and crude oil from 2 MPa to 43.3 MPa at 343.15 K. The results showed that the CO 2 solubility in crude oil and the oil volume expansion were greatly improved due to the addition of alcohols. Especially 1-butanol, 1-pentanol and 1-hexanol were mixed by 8:1:1(volume ratio), 5% (volume ratio) alcohols mixture was added to the crude oil, the CO 2 solubility in crude oil increased by 28.74% at 345.15 K and 19 MPa, and the volume expansion coefficient of crude oil also increased by 4.45% at 345.15 K and 14 MPa. It is encouraging to note that the MMP between CO 2 and crude oil decreases by 9.21% after adding 5% alcohols mixture into crude oil. This article is able to provide a new technique for reducing the MMP between CO 2 and crude oil in the field of enhanced oil recovery.