Migration behavior of CO<sub>2</sub>-crude oil miscible zone

Hao, Yongmao; Li, Jianfa; Kong, Chuixian; Guo, Yingchun; Chen, Zhihao; Wei, Xinlin

doi:10.1080/10916466.2021.1972007

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…At present, physical simulation − and numerical simulation methods , are mainly used in the research of CO 2 miscible flooding. In physical simulations, core displacement experiments − and nuclear magnetic resonance experiments , are mainly used to study the migration law of CO 2 under macroscopic conditions.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO₂ Miscible Flooding under Multiphysics Field Coupling Conditions

Cui

et al. 2023

ACS Omega

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CO 2 miscible flooding in low permeability reservoirs is conducive to significantly improving oil recovery. At present, the microscopic displacement simulation of CO 2 miscible flooding is mainly reflected in the simulation of the seepage process, but the pressure control of the seepage process is lacking, and the simulation of the characterization of CO 2 concentration diffusion is less studied. In view of the above problems, a numerical model of CO 2 miscible flooding is established, and the microscopic seepage characteristics of interphase mass transfer in CO 2 miscible flooding are analyzed by multiphysics field coupling simulations at the two-dimensional pore scale. The injection velocity, contact angle, diffusion coefficient, and initial injection concentration are selected to analyze their effects on the microscopic seepage characteristics of CO 2 miscible flooding and the concentration distribution in the process of CO 2 diffusion. The research shows that after injection into the model, CO 2 preferentially diffuses into the large pore space and forms a miscible area with crude oil through interphase mass transfer, and the miscible area expands continuously and is pushed to the outlet by the high CO 2 concentration area. The increase in injection velocity will accelerate the seepage process of CO 2 miscible displacement, which will increase the sweep area at the same time. The increase in contact angle increases the seepage resistance of CO 2 and weakens the interphase mass transfer with crude oil, resulting in a gradual decrease in the final recovery efficiency. When the diffusion coefficient increases, the CO 2 concentration in the small pores and the parts that are difficult to reach at the model edge will gradually increase. The larger the initial injection concentration is, the larger the CO 2 concentration in the large pore and miscible areas in the sweep region at the same time. This study has guiding significance for the field to further understand the microscopic seepage characteristics of CO 2 miscible flooding under the effect of interphase mass transfer.

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Section: Introductionmentioning

confidence: 99%

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO₂ Miscible Flooding under Multiphysics Field Coupling Conditions

Cui

et al. 2023

ACS Omega

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“…The sweep coefficients were calculated assuming that the oil displacement efficiency of gas flooding was 100%. Hao et al [38] established a numerical simulation model of miscible flooding, delineating the contour line with oil and gas interfacial tension equal to 0.1 dyn/cm as the rear edge of the miscible zone and taking the CO 2 content in the oil phase equal to 20% as the front edge of the miscible zone, thus obtaining the sweep coefficient of CO 2 miscible flooding. Li et al [39] established a mathematical model of miscible flooding considering CO 2 diffusion and adsorption and defined the location where a dimensionless CO 2 concentration of C/C 0 = 0.5 serves as the miscible front and the place where C/C 0 = 0.95 serves as the gas phase front to study the migration rule of the CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Front Movement and Sweeping Rules of CO2 Flooding under Different Oil Displacement Patterns

Qi,

Zhou,

Lyu

et al. 2023

Energies

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CO2 flooding is a pivotal technique for significantly enhancing oil recovery in low-permeability reservoirs. The movement and sweeping rules at the front of CO2 flooding play a critical role in oil recovery; yet, a comprehensive quantitative analysis remains an area in need of refinement. In this study, we developed 1-D and 2-D numerical simulation models to explore the sweeping behavior of miscible, immiscible, and partly miscible CO2 flooding patterns. The front position and movement rules of the three CO2 flooding patterns were determined. A novel approach to the contour area calculation method was introduced to quantitatively characterize the sweep coefficients, and the sweeping rules are discussed regarding the geological parameters, oil viscosity, and injection–production parameters. Furthermore, the Random Forest (RF) algorithm was employed to identify the controlling factor of the sweep coefficient, as determined through the use of out-of-bag (OOB) data permutation analysis. The results showed that the miscible front was located at the point of maximum CO2 content in the oil phase. The immiscible front occurred at the point of maximum interfacial tension near the production well. Remarkably, the immiscible front moved at a faster rate compared with the miscible front. Geological parameters, including porosity, permeability, and reservoir thickness, significantly impacted the gravity segregation effect, thereby influencing the CO2 sweep coefficient. Immiscible flooding exhibited the highest degree of gravity segregation, with a maximum gravity segregation degree (GSD) reaching 78.1. The permeability ratio was a crucial factor, with a lower limit of approximately 5.0 for reservoirs suitable for CO2 flooding. Injection–production parameters also played a pivotal role in terms of the sweep coefficient. Decreased well spacing and increased gas injection rates were found to enhance sweep coefficients by suppressing gravity segregation. Additionally, higher gas injection rates could improve the miscibility degree of partly miscible flooding from 0.69 to 1.0. Oil viscosity proved to be a significant factor influencing the sweep coefficients, with high seepage resistance due to increasing oil viscosity dominating the miscible and partly miscible flooding patterns. Conversely, gravity segregation primarily governed the sweep coefficient in immiscible flooding. In terms of controlling factors, the permeability ratio emerged as a paramount influence, with a factor importance value (FI) reaching 1.04. The findings of this study can help for a better understanding of sweeping rules of CO2 flooding and providing valuable insights for optimizing oil recovery strategies in the field applications of CO2 flooding.

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“…Hao. et al [27] established a numerical simulation model of miscible flooding, delineating the contour line with oil and gas interfacial tension equal to 0.1 dyn/cm as the rear edge of the miscible zone, and taking the CO2 content in the oil phase equal to 20% as the front edge of the miscible zone, thus obtaining the sweep coefficient of CO2 miscible flooding. Li.…”

Section: Introductionmentioning

confidence: 99%

Front Movement and Sweeping Rules of CO2 Flooding under Different Oil Displacement Patterns

Qi,

Zhou,

Lyu

et al. 2023

Preprint

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CO2 flooding stands as a pivotal technique for significantly enhancing oil recovery in low-permeability reservoirs. The movement and sweeping rules at the front of CO2 flooding play a critical role in its oil recovery, yet a comprehensive quantitative analysis remains an area in need of refinement. In this study, we have developed 1D and 2D numerical simulation models to explore the sweeping behavior of miscible, immiscible, and partly-miscible CO2 flooding patterns. The front position and movement rules of the three CO2 flooding patterns are determined. A novel approach of the contour area calculation method is introduced to quantitatively characterize the sweep coefficients, and the sweeping rules are discussed regarding geological parameters, oil viscosity, and injection-production parameters. Furthermore, the Random Forest (RF) algorithm is employed to identify the controlling factor of the sweep coefficient, as determined by out-of-bag (OOB) data displacement analysis. The results show that the miscible front is located at the point of maximum CO2 content in the oil phase. The immiscible front occurs at the point of maximum interfacial tension near the production well. Remarkably, the immiscible front moves at a faster rate compared to the miscible front. Geological parameters, including porosity, permeability, and reservoir thickness, significantly impact the gravity segregation effect, thereby influencing the CO2 sweep coefficient. Immiscible flooding exhibits the highest degree of gravity segregation, with a maximum gravity segregation degree (GSD) reaching 78.1. The permeability ratio is a crucial factor, with a lower limit of approximately 5.0 for reservoirs suitable for CO2 flooding. Injection-production parameters also play a pivotal role in sweep coefficient. Decreased well spacing and increased gas injection rates are found to enhance sweep coefficients by suppressing gravity segregation. Additionally, higher gas injection rates can improve the miscibility degree of partly-miscible flooding from 0.69 to 1.0. Oil viscosity proves to be a significant factor influencing the sweep coefficients, with high seepage resistance due to increasing oil viscosity dominating the miscible and partly-miscible flooding patterns. Conversely, gravity segregation primarily governs the sweep coefficient in immiscible flooding. In terms of controlling factors, the permeability ratio emerges as a paramount influence, with a factor importance value (FI) reaching 1.04. these results provide a theoretical foundation for the application of CO2 flooding, enhancing the understanding of the critical factors governing its success.

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Migration behavior of CO₂-crude oil miscible zone

Cited by 5 publications

References 13 publications

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO₂ Miscible Flooding under Multiphysics Field Coupling Conditions

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO₂ Miscible Flooding under Multiphysics Field Coupling Conditions

Front Movement and Sweeping Rules of CO2 Flooding under Different Oil Displacement Patterns

Front Movement and Sweeping Rules of CO2 Flooding under Different Oil Displacement Patterns

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Migration behavior of CO2-crude oil miscible zone

Cited by 5 publications

References 13 publications

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO2 Miscible Flooding under Multiphysics Field Coupling Conditions

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO2 Miscible Flooding under Multiphysics Field Coupling Conditions

Front Movement and Sweeping Rules of CO2 Flooding under Different Oil Displacement Patterns

Front Movement and Sweeping Rules of CO2 Flooding under Different Oil Displacement Patterns

Contact Info

Product

Resources

About

Migration behavior of CO₂-crude oil miscible zone

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO₂ Miscible Flooding under Multiphysics Field Coupling Conditions

Simulation of Microscopic Seepage Characteristics of Interphase Mass Transfer in CO₂ Miscible Flooding under Multiphysics Field Coupling Conditions