Improved Method for the Estimation of Minimum Miscibility Pressure for Pure and Impure CO2–Crude Oil Systems Using Gaussian Process Machine Learning Approach

Abstract The minimum miscibility pressure (MMP) is one of the critical parameters needed in the successful design of a miscible gas injection for enhanced oil recovery purposes. In this study, we explore the capability of using the Gaussian process machine learning (GPML) approach, for accurate prediction of this vital property in both pure and impure CO2-injection streams. We first performed a sensitivity analysis of different kernels and then a comparative analysis with other techniques. The new GPML model, when compared with previously published predictive models, including both correlations and other machine learning (ML)/intelligent models, showed superior performance with the highest correlation coefficient and the lowest error metrics.

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Machine Learning Predictive Models to Estimate the Minimum Miscibility Pressure of CO2-Oil System

10.2118/207865-ms ◽

2021 ◽

Author(s):

Abderraouf Chemmakh ◽

Ahmed Merzoug ◽

Habib Ouadi ◽

Abdelhak Ladmia ◽

Vamegh Rasouli

Keyword(s):

Machine Learning ◽

Predictive Models ◽

Critical Parameters ◽

Co2 Injection ◽

Learning Models ◽

Minimum Miscibility Pressure ◽

Reservoir Conditions ◽

Important Amount ◽

Machine Learning Models

Abstract One of the most critical parameters of the CO2 injection (for EOR purposes) is the Minimum Miscibility Pressure MMP. The determination of this parameter is crucial for the success of the operation. Different experimental, analytical, and statistical technics are used to predict the MMP. Nevertheless, experimental technics are costly and tedious, while correlations are used for specific reservoir conditions. Based on that, the purpose of this paper is to build machine learning models aiming to predict the MMP efficiently and in broad-based reservoir conditions. Two ML models are proposed for both pure CO2 and non-pure CO2 injection. An important amount of data collected from literature is used in this work. The ANN and SVR-GA models have shown enhanced performance comparing to existing correlations in literature for both the pure and non-pure models, with a coefficient of R2 0.98, 0.93 and 0.96, 0.93 respectively, which confirms that the proposed models are reliable and ready to use.

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Key Problems in the Calculation of Minimum Miscibility Pressure Based on Analytical Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.361-363.516 ◽

2011 ◽

Vol 361-363 ◽

pp. 516-519

Author(s):

Ju Li ◽

Xin Wei Liao ◽

Su Kun

Keyword(s):

Oil Recovery ◽

Accurate Determination ◽

Gas Injection ◽

Analytical Calculation ◽

Minimum Miscibility Pressure ◽

Recovery Techniques ◽

Miscible Gas Injection ◽

Tie Lines ◽

Successful Design ◽

Complete Set

Miscible and/or near miscible gas injection processes are among the most widely used enhanced oil recovery techniques. The successful design and implementation of a miscible gas injection project is dependent upon the accurate determination of minimum miscible pressure (MMP), the pressure above which the displacement process becomes multi-contact miscible. Analytical methods, which are inexpensive and quick to use, have been developed to estimate MMP for complex fluid characterizations. However, many problems still existed in the analytical calculation, which will lead to the failure of calculation, or wrong result. This paper shows how the initial tie line could be calculated when the component of injection gas doesn’t included in the crude oil. And moreover, how to get a complete set of initial value for the equations of crossover tie lines, and the influence of EOS for the result of key tie lines is analyzed simultaneously.

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The Effect of Carbonyl and Hydroxyl Compounds on Swelling Factor, Interfacial Tension, and Viscosity in CO2 Injection: A Case Study on Aromatic Oils

Processes ◽

10.3390/pr9010094 ◽

2021 ◽

Vol 9 (1) ◽

pp. 94

Author(s):

Asep Kurnia Permadi ◽

Egi Adrian Pratama ◽

Andri Luthfi Lukman Hakim ◽

Doddy Abdassah

Keyword(s):

Interfacial Tension ◽

Oil Recovery ◽

Viscosity Reduction ◽

Co2 Injection ◽

Minimum Miscibility Pressure ◽

Lower Viscosity ◽

Hydroxyl Compounds ◽

Swelling Factor

A factor influencing the effectiveness of CO2 injection is miscibility. Besides the miscible injection, CO2 may also contribute to oil recovery improvement by immiscible injection through modifying several properties such as oil swelling, viscosity reduction, and the lowering of interfacial tension (IFT). Moreover, CO2 immiscible injection performance is also expected to be improved by adding some solvent. However, there are a lack of studies identifying the roles of solvent in assisting CO2 injection through observing those properties simultaneously. This paper explains the effects of CO2–carbonyl and CO2–hydroxyl compounds mixture injection on those properties, and also the minimum miscibility pressure (MMP) experimentally by using VIPS (refers to viscosity, interfacial tension, pressure–volume, and swelling) apparatus, which has a capability of measuring those properties simultaneously within a closed system. Higher swelling factor, lower viscosity, IFT and MMP are observed from a CO2–propanone/acetone mixture injection. The role of propanone and ethanol is more significant in Sample A1, which has higher molecular weight (MW) of C7+ and lower composition of C1–C4, than that in the other Sample A9. The solvents accelerate the ways in which CO2 dissolves and extracts oil, especially the extraction of the heavier component left in the swelling cell.

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Enhanced Recovery of Nanoconfined Oil in Tight Rocks Using Lean Gas (C2H6 and CO2) Injection

SPE Journal ◽

10.2118/195272-pa ◽

2021 ◽

pp. 1-20

Author(s):

Seunghwan Baek ◽

I. Yucel Akkutlu

Keyword(s):

Free Energy ◽

Oil Recovery ◽

Enhanced Recovery ◽

Source Rocks ◽

Superior Performance ◽

Co2 Injection ◽

Molecular Configuration ◽

Pressure Depletion ◽

Reservoir Conditions ◽

Recovery Mechanisms

Summary Organic matters in source rocks store oil in significantly larger volume than that based on its pore volume (PV) due to so-called nanoconfinement effects. With pressure depletion and production, however, oil recovery is characteristically low because of the low compressibility of the fluid and amplified interaction with pore surface in the nanoporous material. For the additional recovery, CO2 injection has been widely adopted in shale gas and tight oil recovery over the last decades. But its supply and corrosion are often pointed out as drawbacks. In this study, we propose ethane injection as an alternative enhanced oil recovery (EOR) strategy for more productive oil production from tight unconventional reservoirs. Monte Carlo (MC) molecular simulation is used to reconstruct molecular configuration in pores under reservoir conditions. Further, molecular dynamics (MD) simulation provides the basis for understanding the recovery mechanism of in-situ fluids. These enable us to estimate thermodynamic recovery and the free energy associated with dissolution of injected gas. Primary oil recovery is typically below 15%, indicating that pressure depletion and fluid expansion are no longer effective recovery mechanisms. Ethane injection shows 5 to 20% higher recovery enhancement than CO2 injection. The superior performance is more pronounced, especially in nanopores, because oil in the smaller pores is richer in heavy components compared to the bulk fluids, and ethane molecules are more effective in displacing the heavy hydrocarbons. Analysis of the dissolution free energy confirms that introducing ethane into reservoirs is more favored and requires less energy for the enhanced recovery.

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Minimum miscibility pressure computation in eor by flare gas flooding

Jurnal Teknik Kimia Indonesia ◽

10.5614/jtki.2011.10.2.3 ◽

2018 ◽

Vol 10 (2) ◽

pp. 61

Author(s):

Tjokorde Walmiki Samadhi ◽

Utjok W.R. Siagian ◽

Angga P Budiono

Keyword(s):

Enhanced Oil Recovery ◽

Oil Recovery ◽

Gas Injection ◽

Molar Ratio ◽

Co2 Injection ◽

Co2 Flooding ◽

Minimum Miscibility Pressure ◽

Gas Flooding ◽

Model Oil ◽

Gas Drive

The technical feasibility of using flare gas in the miscible gas flooding enhanced oil recovery (MGF-EOR) is evaluated by comparing the minimum miscibility pressure (MMP) obtained using flare gas to the MMP obtained in the conventional CO2 flooding. The MMP is estimated by the multiple mixing cell calculation method with the Peng-Robinson equation of state using a binary nC5H12-nC16H34 mixture at a 43%:57% molar ratio as a model oil. At a temperature of 323.15 K, the MMP in CO2 injection is estimated at 9.78 MPa. The MMP obtained when a flare gas consisting of CH4 and C2H6 at a molar ratio of 91%:9% is used as the injection gas is predicted to be 3.66 times higher than the CO2 injection case. The complete gas-oil miscibility in CO2 injection occurs via the vaporizing gas drive mechanism, while flare gas injection shifts the miscibility development mechanism to the combined vaporizing / condensing gas drive. Impact of variations in the composition of the flare gas on MMP needs to be further explored to confirm the feasibility of flare gas injection in MGF-EOR processes. Keywords: flare gas, MMP, miscible gas flooding, EORAbstrakKonsep penggunaan flare gas untuk proses enhanced oil recovery dengan injeksi gas terlarut (miscible gas flooding enhanced oil recovery atau MGF-EOR) digagaskan untuk mengurangi emisi gas rumah kaca dari fasilitas produksi migas, dengan sekaligus meningkatkan produksi minyak. Kelayakan teknis injeksi flare gas dievaluasi dengan memperbandingkan tekanan pelarutan minimum (minimum miscibility pressure atau MMP) untuk injeksi flare gas dengan MMP pada proses MGF-EOR konvensional menggunakan injeksi CO2. MMP diperkirakan melalui komputasi dengan metode sel pencampur majemuk dengan persamaan keadaan Peng-Robinson, pada campuran biner nC5H12-nC16H34 dengan nisbah molar 43%:57% sebagai model minyak. Pada temperatur 323.15 K, estimasi MMP yang diperoleh dengan injeksi CO2 adalah 9.78 MPa. Nilai MMP yang diperkirakan pada injeksi flare gas yang berupa campuran CH4-C2H6 pada nisbah molar 91%:9% sangat tinggi, yakni sebesar 3.66 kali nilai yang diperoleh pada kasus injeksi CO2. Pelarutan sempurna gas-minyak dalam injeksi CO2 terbentuk melalui mekanisme dorongan gas menguap (vaporizing gas drive), sementara pelarutan pada injeksi flare gas terbentuk melaui mekanisme kombinasi dorongan gas menguap dan mengembun (vaporizing/condensing gas drive). Pengaruh variasi komposisi flare gas terhadap MMP perlu dikaji lebih lanjut untuk menjajaki kelayakan injeksi flare gas dalam proses MGF-EOR.Kata kunci: flare gas, MMP, miscible gas flooding, EOR

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A new empirical correlation of minimum miscibility pressure for produced gas reinjection

Energy Exploration & Exploitation ◽

10.1177/0144598719898572 ◽

2020 ◽

Vol 38 (4) ◽

pp. 867-883

Author(s):

Congge He ◽

Zifei Fan ◽

Chenshuo Zhang ◽

Anzhu Xu ◽

Lun Zhao ◽

...

Keyword(s):

Crude Oil ◽

Relative Error ◽

Empirical Correlation ◽

Critical Parameters ◽

Average Relative Error ◽

Cell Method ◽

Minimum Miscibility Pressure ◽

Miscible Gas Injection ◽

Acidic Components ◽

Key Parameter

Minimum miscible pressure is a key parameter to screen and design miscible gas injection projects. The aim of this paper is to establish a correlation with only a few input parameters to easily and accurately predict minimum miscible pressure for the reinjection of produced gas with high acidic components. First, the critical parameters of equation of state for each component of the crude oil were obtained through fitting pressure-volume-temperature (PVT) experimental results. Based on the analytically calculated minimum miscible pressures from mixing-cell method, an empirical correlation for predicting minimum miscible pressure in the displacement of crude oil by produced gas was regressed. Finally, the correlation’s accuracy was tested by comparing the minimum miscible pressures predicted from the new proposed correlation to other previous correlations and 20 experimental slim-tube minimum miscible pressures of 12 oil samples. The results indicate that the analytically calculated minimum miscible pressures from the mixing-cell method have a relative error of 0.5% compared to the slim-tube experiment results, which supports its reliability. Furthermore, the new proposed correlation is observed to be superior in terms of the average relative error being only 6.4% for all the 75 analytically calculated minimum miscible pressures and 20 experimental slim-tube minimum miscible pressures, which is lower than the average relative error obtained from other previous correlations.

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Minimum Miscibility Pressure of CO2/Hydrocarbon Systems Within Nanopores

10.1115/omae2021-62633 ◽

2021 ◽

Author(s):

Gang Yang ◽

Xiaoli Li

Keyword(s):

Oil Recovery ◽

Gas Injection ◽

Unconventional Reservoirs ◽

Minimum Miscibility Pressure ◽

Theoretical Approaches ◽

Fluid Systems ◽

Confined Fluid ◽

Miscible Gas Injection ◽

Fluid Characterization ◽

The Impact

Abstract Minimum miscibility pressure (MMP), as a key parameter for the miscible gas injection enhanced oil recovery (EOR) in unconventional reservoirs, is affected by the dominance of nanoscale pores. The objective of this work is to investigate the impact of nanoscale confinement on MMP of CO2/hydrocarbon systems and to compare the accuracy of different theoretical approaches in calculating MMP of confined fluid systems. A modified PR EOS applicable for confined fluid characterization is applied to perform the EOS simulation of the vanishing interfacial tension (VIT) experiments. The MMP of multiple CO2/hydrocarbon systems at different pore sizes are obtained via the VIT simulations. Meanwhile, the multiple mixing cell (MMC) algorithm coupled with the same modified PR EOS is applied to compute the MMP for the same fluid systems. Comparison of these results to the experimental values recognize that the MMC approach has higher accuracy in determining the MMP of confined fluid systems. Moreover, nanoscale confinement results in the drastic suppression of MMP and the suppression rate increases with decreasing pore size. The drastic suppression of MMP is highly favorable for the miscible gas injection EOR in unconventional reservoirs.

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Molecular Modeling of CO2 and n-Octane in Solubility Process and α-Quartz Nanoslit

Energies ◽

10.3390/en11113045 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3045 ◽

Cited By ~ 2

Author(s):

Jun Pu ◽

Xuejie Qin ◽

Feifei Gou ◽

Wenchao Fang ◽

Fengjie Peng ◽

...

Keyword(s):

Interfacial Tension ◽

Oil Recovery ◽

Interfacial Properties ◽

Co2 Injection ◽

Displacement Efficiency ◽

Co2 Solubility ◽

Minimum Miscibility Pressure ◽

Tertiary Oil Recovery ◽

Secondary Oil Recovery ◽

Dynamics Simulations

After primary and secondary oil recovery, CO2-enhanced oil recovery (EOR) has become one of the most mentioned technologies in tertiary oil recovery. Since the oil is confined in an unconventional reservoir, the interfacial properties of CO2 and oil are different from in conventional reservoirs, and play a key role in CO2 EOR. In this study, molecular dynamics simulations are performed to investigate the interfacial properties, such as interfacial tension, minimum miscibility pressure (MMP), and CO2 solubility. The vanishing interfacial tension method is used to get the MMP (~10.8 MPa at 343.15 K) which is in agreement with the reported experimental data, quantitatively. Meanwhile, the diffusion coefficients of CO2 and n-octane under different pressures are calculated to show that the diffusion is mainly improved at the interface. Furthermore, the displacement efficiency and molecular orientation in α-quartz nanoslit under different CO2 injection ratios have been evaluated. After CO2 injection, the adsorbed n-octane molecules are found to be displaced from surface by the injected CO2 and, then, the orientation of n-octane becomes more random, which indicates that and CO2 can enhance the oil recovery and weaken the interaction between n-octane and α-quartz surface. The injection ratio of CO2 to n-octane is around 3:1, which could achieve the optimal displacement efficiency.

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Experimental Investigation on CO2 Injection in Block M

Journal of Chemistry ◽

10.1155/2018/8623020 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Peng Chen ◽

Linlin Wang ◽

Sidun Zhang ◽

Junqiang Fan ◽

Song Lu

Keyword(s):

Crude Oil ◽

Oil Recovery ◽

Co2 Injection ◽

Displacement Efficiency ◽

Minimum Miscibility Pressure ◽

Different Types ◽

Alternate Flooding ◽

Expansion Ability ◽

Strong Expansion ◽

Core Displacement

The purpose of this report was to perform an experimental evaluation of enhanced oil recovery (EOR) using CO2 injection. A slim tube test and PVT experiment are used to determine the minimum miscibility pressure as well as a few related physical properties. Combined with a long core displacement experiment and nuclear magnetic resonance, CO2 flooding and CO2-water alternate flooding are simulated, and the displacement efficiency of different types of pores is evaluated. The results indicate that the minimum miscibility pressure is 32.6 MPa, and the CO2 flooding is at near-miscible conditions at the current formation pressure. The CO2 solubility of crude oil is large, and the crude oil has a strong expansion ability after the CO2 injection, which is beneficial for improving the recovery of CO2. The EOR of CO2-water alternate flooding is 3.97% higher than that of continuous CO2 flooding, and the EOR in the small and middle pores in the CO2-water alternate flooding is clearly higher. These results will be relevant for the future development of Block M.

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A New Predictive Method for CO2-Oil Minimum Miscibility Pressure

Geofluids ◽

10.1155/2021/8868592 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Dangke Ge ◽

Haiying Cheng ◽

Mingjun Cai ◽

Yang Zhang ◽

Peng Dong

Keyword(s):

Enhanced Oil Recovery ◽

Oil Recovery ◽

Accurate Determination ◽

Contact Process ◽

Gas Injection ◽

New Model ◽

Cell Method ◽

Minimum Miscibility Pressure ◽

Miscible Gas Injection ◽

Tie Lines

Gas injection processes are among the effective methods for enhanced oil recovery. Miscible and/or near miscible gas injection processes are among the most widely used enhanced oil recovery techniques. The successful design and implementation of a miscible gas injection project are dependent upon the accurate determination of minimum miscibility pressure (MMP), the pressure above which the displacement process becomes multiple-contact miscible. This paper presents a method to get the characteristic curve of multiple-contact. The curve can illustrate the character in the miscible and/or near miscible gas injection processes. Based on the curve, we suggest a new model to make an accurate prediction for CO2-oil MMP. Unlike the method of characteristic (MOC) theory and the mixing-cell method, which have to find the key tie lines, our method removes the need to locate the key tie lines that in many cases is hard to find a unique set. Moreover, unlike the traditional correlation, our method considers the influence of multiple-contact. The new model combines the multiple-contact process with the main factors (reservoir temperature, oil composition) affecting CO2-oil MMP. This makes it is more practical than the MOC and mixing-cell method, and more accurate than traditional correlation. The method proposed in this paper is used to predict CO2-oil MMP of 5 samples of crude oil in China. The samples come from different oil fields, and the injected gas is pure CO2. The prediction results show that, compared with the slim-tube experiment method, the prediction error of this method for CO2-oil MMP is within 2%.

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