Experimental study on dispersion characteristics and CH4 recovery efficiency of CO2, N2 and their mixtures for enhancing gas recovery

Zhang, Yi; Liu, Shezhan; Chen, Ming-Kun; Xu, Shidang

doi:10.1016/j.petrol.2022.110756

Cited by 8 publications

(3 citation statements)

References 39 publications

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“…It has been found experimentally by the NMR technique that the process of CO 2 gas displacement of CH 4 can be divided into three stages: the initial stage of competitive adsorption, the dominant stage of competitive adsorption, and the attenuated stage of competitive adsorption . Most of the current studies have focused on the gas behavior during the dominant stage of competitive adsorption ,,,− and the recovery, displacement efficiency, and gas separation at the attenuated stage of competitive adsorption. − During the dominant phase of competitive adsorption, Zhang et al found that 0.65–0.7 nm pores exhibited the highest CO 2 selectivity. The pore size corresponding to the maximum methane recovery decreased with increasing pressure, and low temperature is in favor of methane recovery.…”

Section: Introductionmentioning

confidence: 99%

Displacement Characteristics of CO₂ to CH₄ in Heterogeneous Surface Slit Pores

et al. 2023

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Studying the CO2–CH4 displacement process is of great importance to understand the CO2-enhanced shale gas recovery technology. However, most studies have focused on the gas behavior in the reservoir during the dominant stage of competitive adsorption after CO2 injection, as well as the shale gas recovery, displacement efficiency, and gas separation after displacement, while less attention has been paid to the gas behavior during the initial period of displacement. A CO2–CH4 displacement model that can provide a continuous pressure gradient in the displacement direction and a stable back-pressure at the pore outlet was developed based on a heterogeneous surface pore. The model was divided into three areas: CO2 injection area, pore area, and back-pressure area. Molecular dynamics simulations were used to study the effects of depressurization exploitation and injection pressure on the displacement behavior at the initial period of the displacement process under different reservoir conditions. It was found that the displacement process always starts from the CH4 reverse flow stage and then experiences the injection pressure action stage and positive displacement stage in sequence. Moreover, the extent of CH4 reverse flow directly affects the system development process and the final displacement efficiency. A small system presorption pressure and a large injection pressure are beneficial to the displacement. It is believed that the reservoir pressure should be dropped to the lowest possible level during depressurization exploitation, and the CO2 injection pressure needs to be selected by considering displacement efficiency, reservoir safety, and economic cost. The CO2 occupies the adsorption sites near graphene faster than that near montmorillonite (MMT) in the direction of displacement, while the CH4 desorption is faster near MMT. Therefore, it cannot be concluded that the displacement process near graphene is ahead of MMT. It is considered that the gas desorption/adsorption behavior near the graphene dominates the displacement process in terms of gas amount, while the fluctuation near MMT with time and injection pressure directly affects the gas adsorption variation in the pore space from the trend.

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Section: Introductionmentioning

confidence: 99%

Displacement Characteristics of CO₂ to CH₄ in Heterogeneous Surface Slit Pores

et al. 2023

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“…At the same time, N 2 plays an outstanding role in enhanced gas recovery [8,23], due to its abundant resources, sufficient gas source and low cost. In addition, the mixture of CO 2 and N 2 combines the advantages of the two, reducing pore expansion, enhancing gas recovery and allowing for CO 2 storage [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Current Progress and Development Trend of Gas Injection to Enhance Gas Recovery in Gas Reservoirs

Lin,

Wei,

Gao

et al. 2024

Energies

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Conventional recovery enhancement techniques are aimed at reducing the abandonment pressure, but there is an upper limit for recovery enhancement due to the energy limitation of reservoirs. Gas injection for energy supplementation has become an effective way to enhance gas recovery by reducing hydrocarbon saturation in gas reservoirs. This review systematically investigates progress in gas injection for enhanced gas recovery in three aspects: experiments, numerical simulations and field examples. It summarizes and analyzes the current research results on gas injection for EGR and explores further prospects for future research. The research results show the following: (1) Based on the differences in the physical properties of CO2, N2 and natural gas, effective cushion gas can be formed in bottom reservoirs after gas injection to achieve the effects of pressurization, energy replenishment and gravity differentiation water resistance. However, further experimental evaluation is needed for the degree of increase in penetration ability. (2) It is more beneficial to inject N2 before CO2 or the mixture of N2 and CO2 in terms of EGR effect and cost. (3) According to numerical simulation studies, water drive and condensate gas reservoirs exhibit significant recovery effects, while CO2-EGR in depleted gas reservoirs is more advantageous for burial and storage; current numerical simulations only focus on mobility mass and saturation changes and lack a mixed-phase percolation model, which leads to insufficient analysis of injection strategies and a lack of distinction among different gas extraction effects. Therefore, a mixed-phase-driven percolation model that can characterize the fluid flow path is worth studying in depth. (4) The De Wijk and Budafa Szinfelleti projects have shown that gas injection into water drive and depleted reservoirs has a large advantage for EGR, as it can enhance recovery by more than 10%. More experiments, simulation studies and demonstration projects are needed to promote the development of gas injection technology for enhanced recovery in the future.

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“…The water-producing of gas wells was one of the main factors affecting the production stability and recovery rate in the process of gas field development, which led to a drastic decrease in the gas production of gas wells or even stopped production by water flooding. Meanwhile, water in the formation sealed off the reservoir, which made it impossible to recover a large amount of natural gas reserves effectively and drastically reduced the recovery rate [2] . Drainage gas extraction was a technological measure to solve the problem of excessive fluid accumulation or water production in the formation near the wellbore and well bottoming and to restore the gas well to normal production, the purpose of which was to delay and avoid flooding of the gas wells, improved the production condition of the gas reservoir, and increased the efficiency of gas reservoir development and recovery rate, which had a pivotal role in the development process of the gas field [3] .…”

Section: Introductionmentioning

confidence: 99%

Investigation of Gas-liquid Separation Experiment of Electric Pump Drainage and Gas Extraction Unit in High Gas-liquid Ratio Gas Wells

Zhang,

Jing,

et al. 2023

J. Phys.: Conf. Ser.

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Given the prominent problem of water in the Tarim basin of China with high formation temperature and large water production, a preferred scheme of electric pump drainage and gas extraction unit for gas fields with a high gas-liquid ratio is proposed by the mechanical principle and structural design method. Then, the corresponding electric pumps were developed, and the drainage and gas extraction scheme of a permanent magnet electric pump unit with gas-liquid separation in the way of an inverted deflector is designed. Through indoor experiments simulating the downhole gas-liquid ratio environment, the gas-liquid separation ability and adaptability of the design scheme under different good conditions are verified. The results obtained demonstrate that the cable connection process can meet the requirements of high-pressure resistance (≥25 MPa), and the gas-liquid separation effect is very good in vertical wells by adopting the inverted deflector scheme. The separation effect exceeded 90% under different working conditions (production from 30 to 150 m3/day and inhalation gas-liquid ratio from 50% to 95% and even higher) in the experiment with high gas content. The results will promote the gas recovery rate of high gas-liquid ratio gas fields and improve extraction efficiency.

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Experimental study on dispersion characteristics and CH4 recovery efficiency of CO2, N2 and their mixtures for enhancing gas recovery

Cited by 8 publications

References 39 publications

Displacement Characteristics of CO₂ to CH₄ in Heterogeneous Surface Slit Pores

Displacement Characteristics of CO₂ to CH₄ in Heterogeneous Surface Slit Pores

Current Progress and Development Trend of Gas Injection to Enhance Gas Recovery in Gas Reservoirs

Investigation of Gas-liquid Separation Experiment of Electric Pump Drainage and Gas Extraction Unit in High Gas-liquid Ratio Gas Wells

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Experimental study on dispersion characteristics and CH4 recovery efficiency of CO2, N2 and their mixtures for enhancing gas recovery

Cited by 8 publications

References 39 publications

Displacement Characteristics of CO2 to CH4 in Heterogeneous Surface Slit Pores

Displacement Characteristics of CO2 to CH4 in Heterogeneous Surface Slit Pores

Current Progress and Development Trend of Gas Injection to Enhance Gas Recovery in Gas Reservoirs

Investigation of Gas-liquid Separation Experiment of Electric Pump Drainage and Gas Extraction Unit in High Gas-liquid Ratio Gas Wells

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Displacement Characteristics of CO₂ to CH₄ in Heterogeneous Surface Slit Pores

Displacement Characteristics of CO₂ to CH₄ in Heterogeneous Surface Slit Pores