Abstract
Pendant drop method has been used to measure the equilibrium interfacial tension and dynamic interfacial tension of CO2/crude oil system under the simulated-formation condition, in which the temperature is 355.65 K and pressure ranges from 0 MPa to 30 MPa. The test results indicated that the equilibrium interfacial tension of CO2/crude oil systems decreased with the increase of the systematic pressure. The dynamic interfacial tension of CO2/original oil, CO2/remaining oil, and CO2/produced oil systems is large at the initial contact and decreases gradually after that, and then finally it reaches dynamic balance. In addition, the higher the pressure is, the larger the magnitude of changing of CO2/crude oil interfacial tension with time will reduce. Moreover, by PVT phase experiment, gas-oil ratio, gas composition, and well fluid composition have been got, and different contents of light components in three oil samples under reservoir conditions have also been calculated. The relationship between equilibrium interfacial tensions and pressures of three different components of crude oil and CO2system was studied, and the higher C1is, the lower C2–C10will be, and the equilibrium interfacial tension will get higher. Therefore, the effect of light weight fractions on interfacial tension under formation conditions was studied.
Highlights
The EOR technology of gas injection is theoretically better than water injection in the enhancement of oil recovery
Pendant drop has been used to measure the relationship between the equilibrium interfacial tension and the pressure of CO2/crude oil system under the condition of the stratum temperature
The interfacial tension of this time can be seen as the equilibrium interfacial tension
Summary
The EOR technology of gas injection is theoretically better than water injection in the enhancement of oil recovery. CO2 has a great ability to dissolve in liquid [8–15] This is helpful in improving the overall mass transfer rate when supercritical solubility increases and the reservoir structure is conducive to increase inner diffusion and external diffusion, in order to increase the opportunity of the contact of CO2 with oil and make them easier to mix. The data of gas and crude oil interfacial tension under conditions of formation has very important theoretical and practical value, and the key of miscible flooding technology is to determine the minimum miscibility pressure of injection agent and crude oil [23–27]. The phenomenon that the interfacial tension changes with pressure significantly affects the reservoir fluid transfer behavior [28–31]. Miscible flooding technology is considered as one of the most cost-effective methods of EOR [32–35]. Pendant drop has been used to measure the relationship between the equilibrium interfacial tension and the pressure of CO2/crude oil system under the condition of the stratum temperature. The effect of light weight fractions on the interfacial tension under formation conditions was calculated
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