Comparison of enhanced coalbed methane recovery by pure N2 and CO2 injection: Experimental observations and numerical simulation

Wang, Liguo; Wang, Zhaofeng; Li, Kaizhi; Chen, Haidong

doi:10.1016/j.jngse.2015.02.002

Cited by 78 publications

(40 citation statements)

References 21 publications

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“…The control equation of the gas flow field can be derived by the combination of Equations (13)(14) and (22)(23).…”

Section: Mathematical Modelmentioning

confidence: 99%

“…It is well‐known that the methane generated in coal seams is an efficient and clean source of energy . In recent years, coalbed methane (CBM) development has received special attention in areas with multiple coal seams . Several unconventional gas resources located in coal deposits have been studied as systems .…”

Section: Introductionmentioning

confidence: 99%

“…11,12 In recent years, coalbed methane (CBM) development has received special attention in areas with multiple coal seams. [13][14][15][16] Several unconventional gas resources located in coal deposits have been studied as systems. [17][18][19] At present, gas predrainage along coal seam boreholes is mainly used in China, which is also an effective method for coal seam gas recovery and gas disaster prevention and control in coal mines, [20][21][22] as shown in Figure 2.…”

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confidence: 99%

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Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Wang

Chang

et al. 2019

Energy Science & Engineering

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The effective extraction radius of borehole is the main parameter for determining the design and layout for coalbed methane extraction. This paper is aimed at the problem that the criteria and calculation methods for the effective extraction radius of coal seams are not comprehensive. With Wudong Coal Mine in China taken as an example, the critical gas pressure (0.441 MPa) for the calculation of effective extraction radius is first defined. Next, the gas seepage unit model around the borehole is developed, and the theoretical mathematical expression to calculate the effective extraction radius is derived. Then, the numerical simulation of gas extraction is carried out through a computational fluid dynamics program, and the effective extraction radius is obtained numerically. Furthermore, the influence of original gas pressure, borehole diameter, and negative pressure of gas extraction on gas extraction is analyzed. Finally, the results from the theoretical calculation and numerical simulation are validated by the field engineering measurement and the average relative error is small (less than 10%). The results indicate that the effective extraction radius has a linear relationship with the extraction time. Moreover, it is found that the original gas pressure is the main factor affecting the effective extraction radius and the effective extraction radius is proportional to the borehole diameter and negative pressure through analysis. Therefore, the above findings can provide a theoretical basis for determining parameters such as borehole spacing and extraction time of gas extraction in coal mines.

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“…The control equation of the gas flow field can be derived by the combination of Equations (13)(14) and (22)(23).…”

Section: Mathematical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Wang

Chang

et al. 2019

Energy Science & Engineering

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“…Carbon dioxide (CO 2 ) geological storage through reducing the risk of CO 2 migration to the surface is becoming an important method for effective control of greenhouse gas [4][5][6][7]. CO 2 -enhanced coalbed methane (CO 2 -ECBM) recovery is a technology that increases CBM production while controlling greenhouse gas by injecting CO 2 into CBM reservoirs, which has already been applied in several field projects [8][9][10]. At the end of 20th century, a company named Amoco first carried out pilot field of ECBM recovery in the San Juan basin of the United States [11].…”

Section: Introductionmentioning

confidence: 99%

Reservoir Permeability Evolution during the Process of CO2-Enhanced Coalbed Methane Recovery

Wang

Jiang

et al. 2018

Energies

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In this study, we have built a dual porosity/permeability model through accurately expressing the volumetric strain of matrix and fracture from a three-dimensional method which aims to reveal the reservoir permeability evolution during the process of CO2-enhanced coalbed methane (CO2-ECBM) recovery. This model has accommodated the key competing processes of mechanical deformation and adsorption/desorption induced swelling/shrinkage, and it also considered the effect of fracture aperture and effective stress difference between each medium (fracture and matrix). We then numerically solve the permeability model using a group of multi-field coupling equations with the finite element method (FEM) to understand how permeability evolves temporally and spatially. We further conduct multifaceted analyses to reveal that permeability evolution near the wells is the most dramatic. This study shows that the farther away from the well, the gentler the evolution of permeability. The evolution of reservoir permeability near the injection well (IW) and the production well (PW) are very different, due to the combined effects of effective stress changes and gas adsorption and desorption. Furthermore, adsorption is the main controlling factor for the change of permeability for regions near the IW, while the change in effective stress is the main cause for the change in permeability near the PW. Increasing the injection pressure of CO2 will cause the reservoir permeability to evolve more quickly and dynamically.

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“…Reeves and Oudinot (2004a;2004b) carried out a reservoir modeling study based on the Tiffany Unit N 2 -ECBM pilot; the economic result and future field performance were forecast. After the parallel ECBM displacement simulation experiments, Wang et al (2015) found that Coal seam permeability significantly affects the effect of CO 2 or N 2 flooding CH 4 and CO 2 as an injected gas is superior to N 2 . After reviewing the ECBM pilots projects in America and Europe, Oudinot et al (2007) found that coal permeability is reduced with CO 2 injection due to swelling, and is enhanced by N 2 injection.…”

Section: Introductionmentioning

confidence: 99%

Comparative Experiment Study on Nitrogen Injection and Free Desorption of Methane-Rich Bituminous Coal Under Triaxial Loading

Zhang¹,

Ye²,

Tang

et al. 2017

Archives of Mining Sciences

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As a kind of associated geological gas, coalbed methane (CBM) is mainly adsorbed in the coal seam. The coal-methane adsorption phenomenon can be described by Langmuir monolayer adsorptio n model, BET multilayer adsorption model and the Theory of Volume Filling of Micropore (TVFM), whereas the binary gas adsorption phenomenon can be described by the extended Langmuir Model. For the CBM in the low permeability coal seam, the amount of gas released by direct drainage is relatively limited, which cannot eliminate the gas explosion and outburst hazards. Gas injection is an effective method to promote methane drainage. In this paper, the free desorption and nitrogen injection displacement experiments are comparatively analyzed, which allows verifying the effectiveness of nitrogen injection's enhancement to gas drainage. The experiment of injecting nitrogen gas into the coal body shows that the coal fracture can be maintained or expanded by the injected gas pressure so that more methane can be released. The nitrogen injection has a higher time efficiency than that of free desorption as well. The displacement ratio of N 2 /CH 4 is in the range of 1-3. Both the injection pressure and confining pressure affect the displacement ratio. The analysis of the desorbed gas components shows that the relationship between the methane component and gas flooding time is an "inverted S" shape curve, and the appropriate time for the methane collection can be inferred by the time interval of the rapid decline of the curve. Keywords: Gas Injection; Methane; Displacement Ratio; Free Desorption Metan zawarty w złożu węgla występuje w głównej mierze w postaci zaadsorbowanej, jako gaz związany. Zjawisko adsorpcji metanu na węglu opisuje model adsorpcji jednowarstwowej Langmuira, model adsorpcji wielowarstwowej BET oraz teoria objętościowego wypełniania mikroporów. Z kolei procesy desorpcji mieszanin dwóch gazów opisuje rozszerzony model Langmuira. W przypadku metanu zawartego w złożu węgla o niskiej przepuszczalności, ilość gazu uwalnianego poprzez proste odgazowanie jest ograniczona i wciąż nie eliminuje ryzyka wybuchu gazu oraz wyrzutu skał i gazu. Wstrzykiwanie gazów jest jedną ze skutecznych metod odgazowania. W pracy tej przeprowadzono badanie porównawcze rezultatów swobodnej desorpcji gazu oraz wstrzyknięcia do złoża azotu, w celu zademonstrowania skuteczności odgazowania poprzez wprowadzenie azotu. Eksperyment polegający na wstrzykiwaniu azotu do calizny węglowej pokazuje możliwość zachowania lub powiększenia pęknięć w strukturze węgla pod działaniem ciśnienia wstrzykiwanego gazu, co umożliwi uwolnienie większych ilości metanu. Ponadto, wprowadzenie azotu okazuje się rozwiązaniem skuteczniejszym w dłuższym okresie czasu niż swobodna desorpcja. Stosunek wypierającego metan N 2 do CH 4 wynosi w przybliżeniu 1:3. Zarówno ciśnienie wstrzykiwanego gazu jak i wielkość ciśnienia złożowego mają wpływ na tempo wypierania metanu przez azot. Analiza składników desorbowanego gazu wskazuje, że zależność ilości metanu od czasu wypływu gazu opisywan...

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Comparison of enhanced coalbed methane recovery by pure N2 and CO2 injection: Experimental observations and numerical simulation

Cited by 78 publications

References 21 publications

Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Theoretical, numerical, and experimental analysis of effective extraction radius of coalbed methane boreholes by a gas seepage model based on defined criteria

Reservoir Permeability Evolution during the Process of CO2-Enhanced Coalbed Methane Recovery

Comparative Experiment Study on Nitrogen Injection and Free Desorption of Methane-Rich Bituminous Coal Under Triaxial Loading

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