A simplified method for experimentally quantifying crude oil swelling during immiscible carbon dioxide injection

Abstract

Immiscible carbon dioxide (CO 2) injection is one of the highly applied enhanced oil recovery (EOR) methods due to its high oil recovery potential and its ability to store CO 2 in the reservoir. The main mechanism of immiscible CO 2 injection is oil swelling. Generally, oil swelling is measured experimentally or measured using modeling methods. This research conducts oil swelling experiments using a simplified method in order to easily and accurately measure oil swelling and determines some of the most significant factors that may impact oil swelling during CO 2 injection. The impact of varying CO 2 injection pressure, temperature, oil viscosity and oil volume on oil swelling capacity was investigated. The simplified method managed to accurately determine the value of oil swelling for all the experiments. One of the factors that was found to impact the method significantly was the oil volume used. The oil volume in the experimental vessel was found to be extremely important since a large oil volume may result in a false oil swelling value. The oil swelling results were compared to other researches and showed that the method applied had an accuracy of over 90% for all the results obtained. This research introduces a simple method that can be used to measure oil swelling and applies this method to investigate some of the factors that may impact the oil swelling capacity during immiscible CO 2 injection. Keywords Oil swelling • Immiscible carbon dioxide injection • Novel technique List of symbols S o Oil swelling V so Volume of swelled oil V uo Volume of unswelled oil P Pressure of CO 2 V Volume occupied by the experimental vessel z Compressibility factor of CO 2 n Number of moles R Universal gas constant T Temperature at which the experiment is conducted 1 Initial conditions at the beginning of the experiment 2 Final conditions after the experiment was concluded IFT Interfacial tension

Numerical Mechanistic Study of In-Situ CO2 EOR – Kinetics and Recovery Performance Analysis

“…Figure 2-10 shows the octane and CO2 mixture swelling factor based on an EOS model. On top of this, the oil swelling factor is also affected by the reservoir temperature and oil types [22]. Oil swelling factor increases with decreasing temperature if the injection pressure is above MMP.…”

“…In other words, the lighter the oil, the higher will be the swelling factor. Figure 2-11 shows the relationships of oil swelling factor with pressure, temperature, oil viscosity, and oil volume [22]. Oil viscosity reduction in combination with oil swelling is another mechanism of ICE.…”

“…the crude oil and CO2 mixture viscosity at different CO2 concentrations. Researchers[20,21,22,23,24,25] measured the mixture viscosity with different experimental methods. Simon et al…”

Numerical Simulation of CO2 Diffusion in a Multiliquid-Phase System Using Moving Mesh Technology

“…Nowadays, the currently available studies on CO 2 diffusion coefficient mainly focus on the diffusion of CO 2 into the single oil phase, single water phase, − and some simple oil–water systems. Hani et al demonstrate that the phase transition of CO 2 from gas to supercritical state will lead to a significant reduction in the diffusion coefficient of CO 2 in water .…”

“…They also proposed an empirical formula to estimate the gas solubility in crude oil with different API gravities and the correlation between gas diffusion coefficient and crude oil viscosity . Sherif et al proposed a straightforward technique for calculating oil swelling induced by CO 2 diffusion . Li et al developed a procedure that considers oil swelling when using pressure-decay method to calculate the supercritical CO 2 diffusion coefficient in a tight reservoir .…”