Sorption-induced swelling/shrinkage and permeability of coal under stressed adsorption/desorption conditions

Wang, G.X.; Wei, Xiaorong; Wang, K.; Massarotto, P.; Rudolph, Victor

doi:10.1016/j.coal.2010.03.001

Cited by 123 publications

(52 citation statements)

References 15 publications

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“…Technical details on the polyaxial system were reported earlier by Massarotto et al (2010), Wang et al (2007) and Wang et al (2010).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…The work reported here is the result of a collaborative experimental program involving RWTH Aachen University, Stanford University, and the University of Queensland (related reports by Massarotto et al, 2010;Wang et al, 2007;Wang et al, 2010), and focused on the mechanical response and permeability evolution of coal in CBM/ECBM reservoirs. We subjected the sample to mechanical loading and unloading using a polyaxial compaction cell, first in the evacuated state, and then each time after exposing it to either helium, or sorbing N 2 , CH 4 , and CO 2 .…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…et al (2007) and Wang et al (2010) Massarotto et al (2010), Wang (2010 up and procedure compaction cell and fluid pressure system…”

mentioning

confidence: 99%

See 2 more Smart Citations

Sorption and changes in bulk modulus of coal — experimental evidence and governing mechanisms for CBM and ECBM applications

Hol

Gensterblum

Massarotto

2014

International Journal of Coal Geology

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Recent studies report that the stiffness of coal changes, when exposed to sorbing gases such as CH 4 and CO 2 . Although this effect might be potentially important for predicting the in situ mechanical behavior of coal seams during CH 4 production or CO 2 sequestration, very little understanding exists on the underlying mechanisms. In this paper, we report a single, long-duration mechanical test on a large, cube-shaped coal sample (Ruhr Basin, Germany). The sample was subjected to isostatic loading and unloading; first in the evacuated state (as received), and then each time after exposing it to pressurized, non-adsorbing He, or sorbing N 2 , CH 4 , and CO 2 . We find that exposure to sorbing gases led to swelling, which introduced a hysteresis in the stress-strain trajectory followed during mechanical loading. This hysteresis was almost absent in the evacuated state, and its magnitude depended strongly on the amount of adsorption-induced swelling exhibited by the sample. The apparent bulk modulus determined here for the CO 2 -equilibrated state was approximately 25% lower compared to the evacuated state. We qualitatively consider mechanisms that affect the elastic behavior of coal at the matrix and bulk scale, and argue that the observed effects are a combined effect of 1) changes in surface roughness at cleat interfaces and microfractures, and 2) a thermodynamic coupling between stress state, sorption capacity and swelling strain. The changes in stiffness relate to fluid-rock interaction effects, as well as to the presence of fractures, and hence not to the inherent elastic properties of the solid phase itself. We discuss the characteristics of each mechanism and the connection of the proposed mechanisms with formation-scale geomechanical effects of coal layers under conditions relevant to CBM/ECBM.

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“…Technical details on the polyaxial system were reported earlier by Massarotto et al (2010), Wang et al (2007) and Wang et al (2010).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

See 1 more Smart Citation

Sorption and changes in bulk modulus of coal — experimental evidence and governing mechanisms for CBM and ECBM applications

Hol

Gensterblum

Massarotto

2014

International Journal of Coal Geology

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“…More details about the testing with TTSCP can be found elsewhere (Massarotto, 2002;Wang et al, 2010). Experimental results obtained from the TTSCP tests suggested that the variations of anisotropic permeabilities of coal with average net stress, defined as the difference between confined stress acting on a coal sample and fluid pressure in pores, are almost similar in three directions, as shown in Fig.…”

Section: Accepted M Manuscriptmentioning

confidence: 67%

“…A good summary of laboratory experiments on anisotropic permeability of coal has been provided by Massarotto et al (2003b). Further experimental studies on permeability anisotropy of coals were carried out by the authors using a unique true tri-axial stress coal permeameter (TTSCP) (Massarotto, 2002;Wang et al, 2010). The TTSCP was designed with the ability of testing anisotropic permeability evolution of coals using relatively large coal samples under realistic tri-axial stress conditions.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Modeling anisotropic permeability of coal and its effects on CO 2 sequestration and enhanced coalbed methane recovery

Wei

Wang

et al. 2015

International Journal of Coal Geology

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Analysis of the tempo‐spatial effects of hydraulic fracturing by drilling through underground coal mine strata on desorption characteristics

Bai

2018

Energy Science & Engineering

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To elucidate the tempo‐spatial effect and the corresponding mechanism of hydraulic fracturing on gas desorption, the experiments of the hydraulic fracturing in the field and the gas adsorption‐desorption in the laboratory were carried out, respectively. The difference of the effects on the total amount of gas desorption, desorption proportion, moisture content, and in situ gas drainage concentration of the original and fracturing coal samples were studied. The results show that coal moisture increase in the 29 m area of hydraulic fracturing, the greater moisture content and the smaller amount of gas desorption, and the 9 m coal samples moisture content is 2.77 times greater than that of the original coal samples, and whose total amount of gas desorption for 29.8% of the original coal samples. In addition, the closer to the fracturing borehole, the smaller the desorption velocity, which is the fastest in the initial 5 minutes. The desorption velocity of the original coal samples is 5.6 times greater than that of the 9 m coal samples. The desorption proportion of the coal samples is high in early stages, η30 min is 64% (ηi is the proportion of the instantaneous total of gas desorption to the total gas desorption, %), and for η6 h‐12 h is 10%. The tempo‐spatial effects of desorption characteristics can be expressed as the time‐delay effect and a space‐reduction effect. Furthermore, the upper limit of deformation of the coal seam is 3.3‰ and the ability of gas desorption in coal seam significantly decreases. The time of gas drainage concentration exhibits more than 30% increases from the 10 days in the nonfracturing area to 90 days in the fracturing area. Finally, hydraulic fracturing crushes coal, replaces absorption gas, increases the moisture content of coal, reduces various stresses, makes coal shrink, and ultimately achieves the effects of pressure relief and permeability improvement.

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Sorption-induced swelling/shrinkage and permeability of coal under stressed adsorption/desorption conditions

Cited by 123 publications

References 15 publications

Sorption and changes in bulk modulus of coal — experimental evidence and governing mechanisms for CBM and ECBM applications

Sorption and changes in bulk modulus of coal — experimental evidence and governing mechanisms for CBM and ECBM applications

Modeling anisotropic permeability of coal and its effects on CO 2 sequestration and enhanced coalbed methane recovery

Analysis of the tempo‐spatial effects of hydraulic fracturing by drilling through underground coal mine strata on desorption characteristics

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