Study on Enhanced Oil Recovery Mechanism of CO2 Miscible Flooding in Heterogeneous Reservoirs under Different Injection Methods

Article Energy & Fuels

Effect of pore structure on recovery of CO2 miscible flooding efficiency in low permeability reservoirs

Hengli Wang et al.

Summary: Carbon dioxide miscible flooding is proven to be an effective enhanced oil recovery technology for light and medium oil reservoirs. This study specifically investigates the impact of pore structures on CO2 miscible flooding in low permeability reservoirs, revealing a raffinate-layer that remains on the surface of the pore after flooding, affecting oil mobility. The results provide insight for analyzing CO2 miscible flooding in reservoirs with different pore structures and offer technical support for improving CO2 utilization efficiency.

JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING (2022)

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Review Energy & Fuels

Fundamental aspects, mechanisms and emerging possibilities of CO2 miscible flooding in enhanced oil recovery: A review

Narendra Kumar et al.

Summary: This review extensively discusses the various technical aspects of enhancing oil production through the application of miscible CO2, identifying significant research gaps. It covers multiple aspects from theoretical analysis to laboratory experiments and field applications, providing valuable information for a better understanding of this topic.

FUEL (2022)

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Article Energy & Fuels

Study on the migration law of CO2 miscible flooding front and the quantitative identification and characterization of gas channeling

Jing Li et al.

Summary: CO2 miscible flooding can improve crude oil recovery in low permeability reservoirs. However, there have been few quantitative studies on the migration law of CO2 miscible flooding front and the identification of gas channeling time. This study establishes a mathematical model and analyzes the effects of porosity, initial injection concentration, dispersion and adsorption on the migration law of the CO2 miscible flooding front.

JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING (2022)

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Article Thermodynamics

Experimental investigation of CO2 storage and oil production of different CO2 injection methods at pore-scale and core-scale

Yongmao Hao et al.

Summary: This study investigated the CO2 storage and oil production of different CO2 injection schemes through laboratory experiments. The results showed that miscible CO2 injection expanded the CO2 storage area and enhanced oil production, while non-uniform miscibility during this process resulted in poor oil washing efficiency. Water alternating CO2 (WAG) injection inhibited gas overriding and increased the scope of CO2 flow, leading to higher oil production. However, the initial water slug displaced stored CO2, resulting in lower CO2 storage. Overall, miscible injection outperformed immiscible CO2 injection, water flooding, and WAG in terms of oil production, with lower gas production.

ENERGY (2022)

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Article Energy & Fuels

Experimental Study on the Sweep Law of CO2 Miscible Flooding in Heterogeneous Reservoir in Jilin

Wen Li et al.

Summary: This study investigated the sweep characteristics of CO2 miscible flooding and found that gas absorption capacity is a key factor affecting sweep efficiency. The high-permeability layer has a much greater gas absorption capacity than the low-permeability layer, resulting in a significant amount of remaining oil in the low-permeability layer. The displacement process can be divided into three stages.

ENERGIES (2022)

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Article Chemistry, Physical

Interfacial Mass Transfer Characteristics and Molecular Mechanism of the Gas-Oil Miscibility Process in Gas Flooding

Hongwei Yu et al.

Summary: In this study, molecular dynamics simulation was used to investigate the gas flooding process with actual components of Jilin oilfield. The results show that increasing the displacement gas pressure leads to changes in the density of the gas and oil phases, promoting efficient mixing between them. It was also observed that higher CO2 content in the displacement phase results in thicker oil-gas interface and better mixing under the same gas pressure. The minimum miscibility pressure for pure CO2 flooding was found to be much lower than that for pure N-2 flooding, and when these two gases were mixed, the minimum miscibility pressure was in between. Furthermore, the mechanisms of the different miscibility processes for different gas pressure and different displacement gases were explained based on the total energy of the system and the potential of the mean force between the gas and oil phases.

ACTA PHYSICO-CHIMICA SINICA (2022)

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Article Energy & Fuels

Experimental study on oil recovery mechanism of CO2 associated enhancing oil recovery methods in low permeability reservoirs

Jianguang Wei et al.

Summary: In this study, five enhancing oil recovery methods were evaluated through core-injection experiments, with surfactant alternating CO2 flooding (SAC) found to be the most effective in improving oil recovery and reducing water cut. The results suggest that SAC combines the advantages of gas and water, recovering oil from both smaller and larger pores in a higher proportion.

JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING (2021)

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Article Energy & Fuels

Monitoring oil displacement and CO2 trapping in low-permeability media using NMR: A comparison of miscible and immiscible flooding

Mingyu Cai et al.

Summary: Dynamic monitoring of CO2 flooding using online low-field NMR imaging revealed that recovery by miscible flooding was significantly higher than immiscible flooding, primarily due to remnant dissolved CO2 in the miscible zone. CO2 concentrations at the leading edge of the miscible zone were higher than in the immediately adjacent transition zone, and the CO2 retention rate following miscible flooding was also notably higher compared to immiscible flooding.

FUEL (2021)

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Article Energy & Fuels