First-Contact-Miscible and Multicontact-Miscible Gas Injection within a Channeling Heterogeneity System

Abstract

Experimentally measured recoveries, gas cuts, and residual saturations, as well as visual observations, were used to quantify the effects of a channeling heterogeneity system on the efficiency and gas/oil nonequilibrium of first-contact-miscible (FCM) and multicontact-miscible (MCM) displacements. These experiments are the first of their type, because they have enabled a direct insight into the mechanisms of gas/oil flow occurring within such type of heterogeneities, and particularly have provided a firmer understanding of the MCM processes. The key finding in this work is the fact that the produced fluids in all MCM experiments were not in compositional equilibrium. The effect of channeling heterogeneity was to reduce mass transfer between the oil and MCM gas phases throughout the porous medium as a whole, thereby driving the system to be more submiscible and, as such, reducing the sweep and increasing the bypassing. These results were also reflected in the increase in nonequilibrium between gas and oil phases. This work has proved that the channeling heterogeneities, even with small permeability contrast, can distort FCM and MCM displacement patterns considerably. In addition, the results suggested that the performance of MCM processes decrease significantly as the injection rate increases. This was probably due to an interplay between capillary and viscous forces in the heterogeneous model, causing the gas at the highest rate to flow faster into the high permeability stripe, therefore resulting in a larger transition zone, shorter miscibility region, greater nonequilibrium, and, hence, a lesser-efficient flood. This study has important implications for the correct interpretation of core data, and for scale-up processes to reservoir scale, particularly for handling gas/oil nonequilibrium when modeling MCM displacements.

Determination of Minimum Miscibility Pressure of Crude Oil–CO2 System by Oil Swelling/Extraction Test

“…[1] In the petroleum industry, the miscibility is commonly recognized as multicontact miscibility (MCM) wherein the miscibility between the CO 2 and crude oil develops by net transfer of components from the oil into the gas (i.e., vaporization gas drive), or from the gas to the oil (i.e., condensing gas drive). [2][3][4] It has also been proved that reservoir temperature, oil composition, and the quality of injected CO 2 are the key parameters affecting the MMP of CO 2 and oil. [5] If the reservoir pressure is lower than the MMP between the in-place crude oil and CO 2 , the CO 2 injection is classified as an immiscible injection process.…”

Magnetic resonance imaging analysis on the in-situ mixing zone of CO2 miscible displacement flows in porous media

“…The analog fluids are dyed, which is suitable for directly visualization. Batycky, 17 AlWahaibi, 18,19 and Shojaei et al 20 have used alcohol-waterhydrocarbon systems at ambient conditions to mimic the phase behavior of CO 2 -hydrocarbon mixtures in CO 2 miscible displacement at elevated pressures and high temperatures in porous media. Hele-Shaw cells have been considered as an analog to porous media flows.…”

Application of mixed kernels function (MKF) based support vector regression model (SVR) for CO2 – Reservoir oil minimum miscibility pressure prediction

“…The evaporation property of volatile components may increase the gas phase during the multicontact of CO2 and oil, decreasing the oil miscibility with CO2 [10,73], while the intermediate components are easy to mix with CO2 due to their inter-solubility into each other [20,73], thus the increase of volatile to intermediate ratio will increase the MMP [29], as shown in Fig. 11d.…”

“…The displacement efficiency of CO2 is highly dependent on the minimum miscible pressure (MMP) [4,5]. MMP is the minimum pressure at which injected gas can develop multicontact miscibility with the reservoir oil [6][7][8][9][10]. Above this pressure, interfacial tension between these two phases is zero, and there is no difference between the densities of oil and injected gas [10,11].…”

“…MMP is the minimum pressure at which injected gas can develop multicontact miscibility with the reservoir oil [6][7][8][9][10]. Above this pressure, interfacial tension between these two phases is zero, and there is no difference between the densities of oil and injected gas [10,11]. In contrast, at pressure lower than MMP, CO2 will no longer be miscible with oil and the displacement efficiency decreases.…”