Influence and Sensitivity Study of Matrix Shrinkage and Swelling on Enhanced Coalbed Methane Production and CO<sub>2</sub> Sequestration with Mixed Gas Injection

Zhou, Fengde; Yao, Guangqing; Tang, Zhonghua; Orodu, O. D.

doi:10.1260/0144-5987.29.6.759

Cited by 19 publications

(15 citation statements)

References 25 publications

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“…The readers are referred to Palmer 1 and Pan and Connell 4 for a comprehensive review of these models. Coal permeability is sensitive to reservoir stress conditions and the gas sorption-induced swelling/shrinkage behavior 5 – 7 . This information has been extensively used in permeability models (e.g., Shiand–Durucan (SD) permeability model): where k is the permeability, k 0 is the initial permeability, C f is the cleat compressibility, σ is the effective horizontal stress, σ 0 is the initial effective horizontal stress, ε V is the volumetric swelling/shrinkage strain, ν is the Poisson’s ratio, E is the Young’s modulus, p is the pore pressure, and p 0 is the initial pore pressure 8 , 9 .…”

Section: Introductionmentioning

confidence: 99%

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Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions

Peng

Fang

Shen

et al. 2017

Sci Rep

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The cleat compressibility of coal is a key parameter that is extensively used in modeling the coal reservoir permeability for Coal Bed Methane (CBM) recovery. Cleat compressibility is often determined from the permeability measurement made at different confining pressures but with a constant pore pressure. Hence, this parameter ignores the sorption strain effects on the cleat compressibility. By using the transient pulse decay (TPD) technique, this study presents the results from a laboratory characterization program using coal core drilled from different bedding directions to estimate gas permeability and coal cleat compressibility under different pore pressures while maintaining effective stress constant. Cleat compressibility was determined from permeability and sorption strain measurements that are made at different pore pressures under an effective stress constant. Results show that the cleat compressibility of coal increases slightly with the increase of pore pressure. Moreover, the cleat compressibility of Sample P (representing the face cleats in coal) is larger than that of Sample C (representing the butt cleats in coal). This result suggests that cleat compressibility should not be regarded as constant in the modeling of the CBM recovery. Furthermore, the compressibility of face cleats is considerably sensitive to the sorption-induced swelling/shrinkage and offers significant effects on the coal permeability.

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Section: Introductionmentioning

confidence: 99%

“…Other studies also revealed that cleat compressibility is not constant and generally varies with pore pressure and effective stress 1 , 2 , 20 – 22 . Cleat compressibility may also change exponentially with respect to the effective stress change for certain types of coal 5 , 16 .…”

Section: Introductionmentioning

confidence: 99%

Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions

Peng

Fang

Shen

et al. 2017

Sci Rep

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“…CO 2 has the highest adsorption affinity among CO 2 , CH 4 , and N 2 , which are adsorbed gas to coal, but CO 2 injectivity is decreased by the highest reduction in cleat permeability resulting from matrix swelling (Busch and Gensterblum, 2011;Chen et al, 2009;Guo et al, 2008). Thus, mixed gas injection that CO 2 to be injected is mixed with N 2 having the lowest adsorption affinity is proposed as a way to supplement the problem of efficiency reduction in CO 2 injection (Seto et al, 2006;Zhou et al, 2011;Zhu et al, 2002). Lin et al (2008) conducted experiments of permeability alteration by injecting pure CO 2 , CH 4 , and N 2 gas, and various mixing ratios of CO 2 -N 2 mixed gas using crushed coal sample.…”

Section: Introductionmentioning

confidence: 99%

Analysis of methane recovery through CO₂–N₂ mixed gas injection considering gas diffusion phenomenon in coal seam

Seomoon

Lee

Sung

2016

Energy Exploration & Exploitation

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When enhancing coalbed methane recovery using CO 2 or N 2 injection, injected gas flows into coal matrix by diffusion. Gas diffusion velocity varies, depending on gas molecular size and pore geometry which causes different sorption rates of the gas in coal seam. In this aspect, this study provides the fundamental reason for the reduction in gas permeability through cleats and methane recovery during enhanced coalbed methane (ECBM) processes. This reduction occurs not only because of the sorption affinity as reported in previous works, but also because of the characteristics of gas diffusional flow which this study attempted to examine experimentally. From the results obtained by diffusional flow experiment, diffusion coefficient is no longer increased at high pressure. Although CO 2 injection rate is very high, a large amount of CO 2 moves through cleat instead of adsorbed in matrix, which causes early CO 2 breakthrough. In ECBM, N 2 mostly acts as a displacing agent of methane, because co-diffusion of N 2 with methane is more dominant than counter-diffusion owing to its extremely low adsorption affinity. On the other hand, CO 2 is rapidly adsorbed due to its fast increasing rate of diffusion coefficient with pressure increase. Consequently, CO 2 permeability is greatly reduced at the beginning of injection and ultimately becomes the lowest value at the maximum adsorption pressure. Also, delayed methane recovery by fast diffusion and high adsorption affinity of CO 2 occurs accordingly. This study confirms that the CO 2 -N 2 mixed gas injection is advisable comparing to only injecting CO 2 to pursue the prevention of CO 2 injectivity reduction and enhanced methane recovery, simultaneously.

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“…China has the third largest supply of coalbed methane resources in the world (Cui et al, 2008). The exploration and exploitation of coalbed methane have shown great success and several breakthroughs during the past 20 years (Cao et al, 2012a;Zhou et strata. The coal seams that have shown value in coal bed methane research and exploitation include #2, #3, #5, and #11 coal seams.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Pulverized Coal during Coalbed Methane Drainage in Hancheng Block, Shaanxi Province, China

Wei

Cao

Yuan

et al. 2013

Energy Exploration & Exploitation

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Pulverized coal is one of the main controlling factors constraining the capacity of coal-bed methane wells during CBM drainage. The characteristics of pulverized coal can be used to identify the sources of the pulverized coal particles and to develop reasonable means of controlling pulverized coal output. Using light transmission microscopy, laser particle size testing, X-ray diffraction, reflection polarized optical microscopy, and scanning electron microscopy with energy dispersive X, the characteristics of pulverized coal collected during CBM drainage in the Hancheng block were analyzed for concentration, particle size, composition, and morphology. These traits were used to identify the sources of pulverized coal. The results showed that coal body structure (structural damage) was a primary control factor of pulverized coal output. The sizes of the pulverized coal particles tended to be around 100 µm. The main components of pulverized coal were vitrinite and clay minerals. The pulverized coals were divided into groups based on their columnar, flaky, or granular morphology. Columnar pulverized coal may involve the formation of the native structure coal or the fragmented coal that later sustains erosive damage. Flaky pulverized coal may be produced by the flaking of scaled coal or leaf coal. In this way, granular pulverized coal may be produced from granulated coal. Therefore, the morphology of the pulverized coal was found to be related to its coal body structure and to late mechanical destruction.

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Influence and Sensitivity Study of Matrix Shrinkage and Swelling on Enhanced Coalbed Methane Production and CO₂ Sequestration with Mixed Gas Injection

Cited by 19 publications

References 25 publications

Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions

Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions

Analysis of methane recovery through CO₂–N₂ mixed gas injection considering gas diffusion phenomenon in coal seam

Characteristics of Pulverized Coal during Coalbed Methane Drainage in Hancheng Block, Shaanxi Province, China

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Influence and Sensitivity Study of Matrix Shrinkage and Swelling on Enhanced Coalbed Methane Production and CO2 Sequestration with Mixed Gas Injection

Cited by 19 publications

References 25 publications

Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions

Effects of gas sorption-induced swelling/shrinkage on the cleat compressibility of coal under different bedding directions

Analysis of methane recovery through CO2–N2 mixed gas injection considering gas diffusion phenomenon in coal seam

Characteristics of Pulverized Coal during Coalbed Methane Drainage in Hancheng Block, Shaanxi Province, China

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Influence and Sensitivity Study of Matrix Shrinkage and Swelling on Enhanced Coalbed Methane Production and CO₂ Sequestration with Mixed Gas Injection

Analysis of methane recovery through CO₂–N₂ mixed gas injection considering gas diffusion phenomenon in coal seam