Experimental Investigation on Microscopic Residual Oil Distribution During CO2 Huff-and-Puff Process in Tight Oil Reservoirs

Qian, Kun; Yang, Shenglai; Dou, Haiyang; Wang, Qian; Wang, Lu; Huang, Yilun

doi:10.3390/en11102843

Cited by 42 publications

(38 citation statements)

References 37 publications

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“…Consequently, oil recovery factor (RF) is further improved by eliminating or reducing IFT through multiple contacts of CO2 and oil in reservoirs [9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO₂ and Water–Alternating-CO₂ (CO₂–WAG) Flooding at Miscible Pressures

et al. 2019

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Blockage in reservoirs caused by asphaltene deposits and inorganic interactions is a serious problem that may exacerbate the complexity of displacement characteristics in heterogeneous multilayer sandstone reservoirs and affect crude oil recovery performance during CO2 and CO2-WAG flooding. In this study, experiments of both CO2 and CO2-WAG flooding were carried out on the same multilayer systems under miscible conditions (70℃, 18 MPa). The two flooding methods were evaluated for oil production performance and reservoir damage. The experimental results indicate that, after CO2 flooding, the entire system has a low oil recovery factor (RF) of 27.6%, and oil is produced mainly from the high permeability layer (91.4%), whilst the residual oil remains predominantly in the medium and low permeability layers. The injection pressure of CO2-WAG flooding is high, but the timing of CO2 breakthrough (BT) is late, and the oil RF of the entire system reaches 44.5%. The contribution rate of oil production in medium and low permeability layers is improved to 3.8% and 17.1%, respectively. Furthermore, the permeability of the high permeability layer decreases by 16.8% after CO2 flooding, which is mainly due to asphaltene precipitation. However, after CO2-WAG flooding, the permeability of each layer is significantly reduced, namely by 29.4%, 16.8% and 6.9% respectively. Asphaltene precipitation is still the main factor, but permeability decline caused by CO2-brine-rock interactions cannot be ignored, especially in the high permeability layer (6.1%). Therefore, for multilayer reservoirs with high heterogeneity, CO2-WAG flooding provides the better oil displacement performance, but prevention and control measures for asphaltene precipitation are more necessary.

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“…Consequently, oil recovery factor (RF) is further improved by eliminating or reducing IFT through multiple contacts of CO2 and oil in reservoirs [9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO₂ and Water–Alternating-CO₂ (CO₂–WAG) Flooding at Miscible Pressures

et al. 2019

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“…Foam has different applications in oil and gas industry such as in drilling, hydraulic fracturing, and in enhanced oil recovery (EOR) [2][3][4][5][6]. CO 2 flooding is one of the most commonly used EOR method that involves the injection of compressed CO 2 [7][8][9]. In EOR methods that employ low viscous fluids as displacing slugs such as CO 2 flooding, the foam is applied to improve the sweep efficiency by controlling the gas mobility.…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach to Stabilize Foam Using Fluorinated Surfactants

Kamal

2019

Energies

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Selection of surfactants for enhanced oil recovery and other upstream applications is a challenging task. For enhanced oil recovery applications, a surfactant should be thermally stable, compatible with reservoir brine, and have lower adsorption on reservoir rock, have high foamability and foam stability, and should be economically viable. Foam improves the oil recovery by increasing the viscosity of the displacing fluid and by reducing the capillary forces due to a reduction in interfacial tension. In this work, foamability and foam stability of two different surfactants were evaluated using a dynamic foam analyzer. These surfactants were fluorinated zwitterionic, and hydrocarbon zwitterionic surfactants. The effect of various parameters such as surfactant type and structure, temperature, salinity, and type of injected gas was investigated on foamability and foam stability. The foamability was assessed using the volume of foam produced by injecting a constant volume of gas and foam stability was determined by half-life time. The maximum foam generation was obtained using hydrocarbon zwitterionic surfactant. However, the foam generated using fluorinated zwitterionic surfactant was more stable. A mixture of zwitterionic fluorinated and hydrocarbon fluorinated surfactant showed better foam generation and foam stability. The foam generated using CO2 has less stability compared to the foam generated using air injection. Presence of salts increases the foam stability and foam generation. At high temperature, the foamability of the surfactants increased. However, the foam stability was reduced at high temperature for all type of surfactants. This study helps in optimizing the surfactant formulations consisting of a fluorinated and hydrocarbon zwitterionic surfactant for foam injections.

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“…The technologies of horizontal drilling and multistage hydraulic fracturing have attracted much attention, especially for the micro-and nano-pores in the unconventional reservoirs [4,5]. The combination of these technologies is extensively used to exploit the reserves in the tight and shale reservoirs [6,7]. However, Dejam et al [8,9] pointed out that low permeability may increase the threshold pressure gradient, and large amount of oil still reserves in the formations, which requires gas injection for the production enhancement [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Cyclic CH4 Injection for Enhanced Oil Recovery in the Eagle Ford Shale Reservoirs

Zhang

Yang

et al. 2018

Energies

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Gas injection is one of the most effective enhanced oil recovery methods for the unconventional reservoirs. Recently, CH4 has been widely used; however, few studies exist to accurately evaluate the cyclic CH4 injection considering molecular diffusion and nanopore effects. Additionally, the effects of operation parameters are still not systematically understood. Therefore, the objective of this work is to build an efficient numerical model to investigate the impacts of molecular diffusion, capillary pressure, and operation parameters. The confined phase behavior was incorporated in the model considering the critical property shifts and capillary pressure. Subsequently, we built a field-scale simulation model of the Eagle Ford shale reservoir. The fluid properties under different pore sizes were evaluated. Finally, a series of studies were conducted to examine the contributions of each key parameter on the well production. Results of sensitivity analysis indicate that the effect of confinement and molecular diffusion significantly influence CH4 injection effectiveness, followed by matrix permeability, injection rate, injection time, and number of cycles. Primary depletion period and soaking time are less noticeable for the well performance in the selected case. Considering the effect of confinement and molecular diffusion leads to the increase in the well performance during the CH4 injection process. This work, for the first time, evaluates the nanopore effects and molecular diffusion on the CH4 injection. It provides an efficient numerical method to predict the well production in the EOR process. Additionally, it presents useful insights into the prediction of cyclic CH4 injection effectiveness and helps operators to optimize the EOR process in the shale reservoirs.

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Experimental Investigation on Microscopic Residual Oil Distribution During CO2 Huff-and-Puff Process in Tight Oil Reservoirs

Cited by 42 publications

References 37 publications

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO₂ and Water–Alternating-CO₂ (CO₂–WAG) Flooding at Miscible Pressures

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO₂ and Water–Alternating-CO₂ (CO₂–WAG) Flooding at Miscible Pressures

A Novel Approach to Stabilize Foam Using Fluorinated Surfactants

Cyclic CH4 Injection for Enhanced Oil Recovery in the Eagle Ford Shale Reservoirs

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Experimental Investigation on Microscopic Residual Oil Distribution During CO2 Huff-and-Puff Process in Tight Oil Reservoirs

Cited by 42 publications

References 37 publications

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO2 and Water–Alternating-CO2 (CO2–WAG) Flooding at Miscible Pressures

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO2 and Water–Alternating-CO2 (CO2–WAG) Flooding at Miscible Pressures

A Novel Approach to Stabilize Foam Using Fluorinated Surfactants

Cyclic CH4 Injection for Enhanced Oil Recovery in the Eagle Ford Shale Reservoirs

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Resources

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Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO₂ and Water–Alternating-CO₂ (CO₂–WAG) Flooding at Miscible Pressures

Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO₂ and Water–Alternating-CO₂ (CO₂–WAG) Flooding at Miscible Pressures