Determination of the minimum miscibility pressure of the CO2/oil system based on quantification of the oil droplet volume reduction behavior

Cui, Xincheng; Zheng, Lichen; Liu, Zhiwei; Cui, Peixuan; Du, Dongxing

doi:10.1016/j.colsurfa.2022.130058

Cited by 16 publications

(5 citation statements)

References 61 publications

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“…Besides, the estimated IFT in this research is also compared with that of the experimental IFT data in reference [17], as shown in Figure 6. It is found that the simulated results are close to those of the reference [17], with an average absolute relative deviation (AARD) of about 7.2%.…”

Section: Resultsmentioning

confidence: 99%

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Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

Sun

et al. 2023

Geofluids

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CO2 flooding is recognized as an efficient method for enhancing shale oil recovery, while CO2-oil MMP (minimum miscibility pressure) in the micro-nanoscale is a crucial parameter. This paper presents a method for calculating the MMPs of pure hydrocarbons (C4H10, C6H14, C8H18, and C10H22) and CO2 systems in nanopores (3 nm to 10 nm) with temperature ranging from 290.15 K to 373.15 K. Firstly, we modify the Peng-Robinson equation of state (PR-EOS) by considering the influence of confinement effect and capillary pressure in nanopores. Secondly, the flash calculation algorithm is employed to determine whether the oil and gas phases in nanopores have reached an equilibrium state according to the equality of the fugacity of the two phases. Thirdly, we calculate the interfacial tension (IFT) between the two phases using the Macleod-Sugden equation. When the extrapolated IFT is zero, we treat the corresponding pressure as the MMP of the CO2-oil system in nanopores. Simulation results indicate that the calculated MMP using this method has a relative error of about 0.62% compared to the MMP calculated using the multiple mixing cell (MMC) method, indicating high reliability for MMP prediction. Moreover, the measured MMP at the nanoscale is generally smaller than that in the bulk phase due to the influence of the confinement effect. The MMP is positively correlated with the reservoir temperature, the carbon atom number in alkanes, and the nanopore radius.

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Section: Resultsmentioning

confidence: 99%

“…MMP is a crucial parameter to verify whether CO 2 and crude oil are miscible or not. It is significant to obtain the oil-CO 2 MMP in the micro-nanoscale [17][18][19][20]. The methods for determining the MMP primarily involve experimental methods and theoretical calculation methods [21].…”

Section: Introductionmentioning

confidence: 99%

Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

Sun

et al. 2023

Geofluids

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“…At the MMP point, the oil droplet will gradually shrink and finally mix with the surrounding CO 2 fluid. Taking advantage of the quick but accurate quantitative volume measurement technique in a state-of-the-art drop shape analyzer, the MMP of the studied two-phase system could therefore be determined as the pressure under which the pendent oil volume in the CO 2 environment continuously decreases with a certain criteria speed . Therefore, ODVM can be considered a time-consuming method for determining MMP.…”

Section: Mmp Determining Methodsmentioning

confidence: 99%

“…Taking advantage of the quick but accurate quantitative volume measurement technique in a state-of-the-art drop shape analyzer, the MMP of the studied two-phase system could therefore be determined as the pressure under which the pendent oil volume in the CO 2 environment continuously decreases with a certain criteria speed. 43 Therefore, ODVM can be considered a time-consuming method for determining MMP. The ODVM is employed to determine the MMPs of the CO 2 /oil system with water present under different temperature levels by Cui et al The results show the water presence could obviously reduce the MMPs of the CO 2 /n-C 16 H 34 system by up to 1.4 MPa.…”

Section: Mmp Determining Methodsmentioning

confidence: 99%

Comprehensive Review of the Determination and Reduction of the Minimum Miscibility Pressure during CO₂ Flooding

Song,

Meng,

Zhang

et al. 2024

ACS Omega

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With the increasing oil demand, more attention has been paid to enhancing oil recovery in old oil fields. CO 2 flooding is popular due to its high oil displacement efficiency and ability to reduce greenhouse gas emissions. Laboratory experiments and on-site application cases have shown that the minimum miscibility pressure has a greater impact on CO 2 flooding than other factors. If the reservoir pressure is below the minimum miscible pressure, then there is CO 2 immiscible flooding. Both theoretical analysis and experimental results show that the recovery rate of CO 2 miscible flooding is 2−5 times higher than that of immiscible flooding. If the reservoir pressure is increased by water flooding before CO 2 injection, it is easily limited by the physical property parameters. Therefore, accurately determining and effectively reducing the minimum mixing pressure has become the focus of research. Currently, there are two types of methods for determining the minimum miscible pressure: experimental and theoretical methods. The experimental method is generally considered more accurate, including the slim tube test, rising bubble apparatus, and vanishing interfacial tension, etc. However, it is worth noting that the minimum miscibility pressure is dynamically changing, and there will be high economic costs if measured repeatedly through experimental methods during reservoir development. Therefore, it is recognized that the minimum mixing pressure can be determined at any time using theoretical calculation of initial data, which will reduce economic and time costs to a high degree. In this paper, the theoretical calculation method is divided into empirical correlation, state equation, and artificial intelligence algorithm. The techniques for reducing the minimum miscibility pressure can be classified into two categories: miscible solvents and surfactant methods. The miscible solvent method can be further divided into monocomponent and polycomponent methods. This paper compares the advantages and disadvantages of the existing techniques for measuring and reducing MMP and selects the best method.

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“…It has a monocline structure with a main burial depth of 2812-4230 m. It is a fan delta deposit with conglomerate lithology. The microscopic cavity structure of the reservoir has a re-modular characteristic; the distribution of the cavity throat is extremely uneven; the pore-throat ratio is large, and the coordination number is low; the overall characteristic of the polyphonic fine state is that the type of cavity gap mainly includes intergranular holes and insulated holes in the granule; the storage layer is heterogeneous and has strong water sensitivity [29][30][31]. These characteristics lead to many challenges in the development process of this type of oil reservoir.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Mechanisms of CO2 Flooding with Varying Degrees of Miscibility in Reservoirs Composed of Low-Permeability Conglomerate Formations

Luo,

Yang,

Zhang

et al. 2024

Processes

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The reservoir type of the MH oil field in the Junggar Basin is a typical low-permeability conglomerate reservoir. The MH oilfield was developed by water injection in the early stage. Nowadays, the reservoir damage is serious, and water injection is difficult. There is an urgent need to carry out conversion injection flooding research to improve oil recovery. The use of CO2 oil-flooding technology can effectively supplement formation energy, reduce greenhouse gas emissions, and improve economic benefits. In order to clarify the feasibility of CO2 flooding to improve oil recovery in conglomerate reservoirs with low permeability, strong water sensitivity, and severe heterogeneity, this paper researched the impact of CO2 miscibility on production characteristics and mechanisms through multi-scale experiments. The aim was to determine the feasibility of using CO2 flooding to enhance oil recovery. This study initially elucidated the oil displacement characteristics of varying degrees of miscibility in different dimensions using slim tube experiments and long core experiments. Subsequently, mechanistic research was conducted, focusing on the produced oil components, changes in interfacial tension, and conditions for pore mobilization. The results indicate that the minimum miscibility pressure (MMP) of the block is 24 MPa. Under the slim tube scale, the increase in the degree of miscibility can effectively delay the gas breakthrough time; under the core scale, once the pressure reaches the near mixing phase, the drive state can transition from a non-mixed “closed-seal” to a “mixed-phase” state. Compared to the immiscible phase, the near-miscible and completely miscible phase can improve the final recovery efficiency by 9.27% and 18.72%. The component differences in the displacement products are mainly concentrated in the high-yield stage and gas breakthrough stage. During the high-yield stage, an increase in miscibility leads to a higher proportion of heavy components in the produced material. Conversely, in the gas breakthrough stage, extraction increases as the level of mixing increases, demonstrating the distinct extracting characteristics of different degrees of mixed phases. The core experiences significant variations in oil saturation mostly during the pre-gas stage. CO2 miscible flooding can effectively utilize crude oil in tiny and medium-sized pores during the middle stage of flooding, hence reducing the minimum threshold for pore utilization to 0.3 μm.

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Determination of the minimum miscibility pressure of the CO2/oil system based on quantification of the oil droplet volume reduction behavior

Cited by 16 publications

References 61 publications

Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

Comprehensive Review of the Determination and Reduction of the Minimum Miscibility Pressure during CO₂ Flooding

Characteristics and Mechanisms of CO2 Flooding with Varying Degrees of Miscibility in Reservoirs Composed of Low-Permeability Conglomerate Formations

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Determination of the minimum miscibility pressure of the CO2/oil system based on quantification of the oil droplet volume reduction behavior

Cited by 16 publications

References 61 publications

Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

Nanometer-Scale CO2-Shale Oil Minimum Miscibility Pressure Calculations Based on Modified PR-EOS

Comprehensive Review of the Determination and Reduction of the Minimum Miscibility Pressure during CO2 Flooding

Characteristics and Mechanisms of CO2 Flooding with Varying Degrees of Miscibility in Reservoirs Composed of Low-Permeability Conglomerate Formations

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Comprehensive Review of the Determination and Reduction of the Minimum Miscibility Pressure during CO₂ Flooding