Super-critical CO2 saturation-induced mechanical property alterations in low rank coal: An experimental study

Ranathunga, A.S.; Perera, M.S.A.; Ranjith, P.G.; Bui, Ha H.

doi:10.1016/j.supflu.2015.11.010

Cited by 89 publications

(52 citation statements)

References 29 publications

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“…Both types of coal were obtained immediately after mining and therefore had been subjected to minimal environmental effects such as dusting, water evaporation or sunlight. The samples used for the present study were the same specimens obtained from the same coal blocks used by Perera, Ranjith and Viete [15] (black coal) and Ranathunga et al [16] (brown coal) and the water content of the blocks was checked before coring new samples to ensure that the coal blocks were not subjected to any moisture loss. The physical properties of the samples used are shown in Table 2.…”

Section: Samples Used For Testingmentioning

confidence: 99%

“…Samples of 38 mm in diameter and 76 mm in height were used for testing purposes and the samples were maintained in a fog room wrapped in plastic wraps (after coring from the coal blocks) before being used for the saturations to preserve natural conditions. The detailed methodology adopted to prepare the samples is discussed in Ranathunga, Perera, Ranjith and Bui [16]. …”

Section: Samples Used For Testingmentioning

confidence: 99%

“…pressures (2 and 6 MPa) additional to those used in the study of Perera, Ranjith and Viete [15] for comparison purposes. Here the samples were saturated under 35 °C temperature to provide similar conditions to those used for CO2 saturation in Ranathunga, Perera, Ranjith and Bui [16] and Perera, Ranjith and Viete [15]. It should be noted that upon the completion of each saturation, the pressure cell was depressurized gradually at a quite slow rate of around 0.02 MPa/min to avoid any possible damage to the coal mass caused by the sudden pressure release.…”

Section: Water Saturationmentioning

confidence: 99%

“…Particularly in the geomechanical respect, the coal mass becomes weaker with the substitution of existing adsorbate CH 4 with the highly chemically potential CO 2 [13,14]. According to Perera et al [15], Ranathunga et al [16] and Vishal et al [17], the inherent brittleness of the coal mass becomes ductile with the plasticization effect of coal with the adsorption of CO 2 , and this phenomena is higher for super-critical CO 2 (beyond the critical temperature of CO 2 -31.8˝C and the critical pressure of CO 2 -7.38 MPa). Generally, potential CO 2 -ECBM reservoirs are located deep underground, where CO 2 is in its super-critical state [2].…”

Section: Introductionmentioning

confidence: 99%

“…This is quite a low pore pressure condition and it is important to see this effect under much greater pore pressure conditions for possible field application. Regarding the rank effect, although there have been some studies to date [16,25] on the effect of CO 2 saturation on different ranks of coal, none of them has considered the rank-dependent mechanical behavior of coal mass under N 2 saturation, particularly under high saturation pressure conditions. Therefore, it is interesting to investigate how coal mechanical property alterations vary under high N 2 saturation conditions and the rank effect on them, which will in turn enable more reliable applications for field projects.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

2016

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During CO 2 sequestration in deep coal seams, the coal mass may be subjected to various fluid (CO 2 , N 2 , etc.) saturations. Therefore, in order to maintain the long-term integrity of the process, it is necessary to identify the mechanical responses of preferable coal seams for various fluid saturations. To date, many studies have focused on the CO 2 saturation effect on coal mass strength and less consideration has been given to the influence of other saturation mediums. Hence, this study aims to investigate coal's mechanical responses to water and N 2 saturations compared to CO 2 saturation and to determine the effect of coal-rank. A series of unconfined compressive strength (UCS) tests was conducted on Australian brown and black coal samples saturated with water and N 2 at various saturation pressures. An advanced acoustic emission (AE) system was utilized to identify the changes in crack propagation behaviors under each condition. According to the results, both CO 2 and water act similarly with coal by enhancing the ductile properties of the coal mass and this mechanical weakening is greater for high-rank coal. Conversely, N 2 saturation slightly enhances coal strength and delays crack propagation in coal and this strength enhancement can be improved by increasing the N 2 saturation pressure.

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Section: Samples Used For Testingmentioning

confidence: 99%

Section: Samples Used For Testingmentioning

confidence: 99%

Section: Water Saturationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

2016

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In‐situ temperature‐depth profile evaluation of South African unmineable coal seams to determine CO₂ sequestration potential

Premlall,

Kipyegon

2023

Can J Chem Eng

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This study aimed to investigate the sorption behaviour of South African coal seams with relation to the effect of temperature during CO2 sequestration. The excess adsorption isotherms of CO2 adsorption were undertaken using a high‐pressure volumetric system for four coals of different coal rank (denoted by Somkele [SK], anthracite KZN [AN], Tshikondeni [TD], and Syferfontein [SF]). The volumetric pressure step method was conducted at increments of system temperature of 35, 45, 55, and 65°C for pure CO2 adsorption at incremental pressures up to 93 bar. The results showed that high temperatures have a very significant negative effect on the amount of CO2 adsorbed on the coal samples. The high‐rank coal samples (SK and AN) demonstrated elevated CO2 adsorption capacity across all tested temperatures due to their high vitrinite content. The medium‐rank coals (TD and SF) exhibited comparatively lower CO2 adsorption capacity, attributed to the presence of adsorption hindrances such as higher ash content and volatile and mineral matter. The isosteric heat of adsorption revealed an increasing trend with coverage for all coal samples, with higher rank coals displaying greater slopes. The determined range of the isosteric heat of adsorption, spanning from 10 to 59 kJ/mol, indicated that the adsorption process is primarily of a physisorption nature. Three theoretical models (Langmuir, Freundlich, and Temkin) were evaluated and fitted to the sorption experimental data. The Temkin model exhibited superior fitting compared to the Langmuir and Freundlich isotherms. The Temkin isotherm parameters suggest that the adsorption of CO2 onto coal is a physisorption process.

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Study on damage and failure characteristics of loaded gas‐bearing rock–coal–rock combination structures

Du,

Wang,

Yang

et al. 2024

Deep Underground Science and Engineering

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The essence of the outburst–rock burst compound dynamic disaster is the disaster behavior of the “gas‐coal‐surrounding rock” system under the comprehensive action of the stress field and the seepage field. Based on the geological occurrence characteristics of coal and rock in the roof, coal, and floor, this study combined experimental research and theoretical analysis to explore the effects of confining pressure, gas pressure, and axial loading rate on the mechanical behavior of gas‐bearing rock–coal–rock combination structures (“RCR combination”). The results show that both decreasing gas pressure and increasing confining pressure can improve the deformation capacity and bearing capacity of the RCR combination. When the gas pressure decreases from 1.5 to 0.5 MPa and the confining pressure increases from 3 to 9 MPa, the peak stress of the RCR combination increases by 15.83% and 184.02%, respectively. On increasing the axial loading rate, the peak stress of the RCR combination first increases and then decreases, and the elastic modulus continues to decrease. There is a good correspondence between stress and acoustic emission counts (AE), which can be used as a predictive index for judging rock fracture instability. Compared with rock, coal exerts much greater influence on the mechanical strength of the RCR combination. The theoretical analysis shows that the parameters m and F0 mainly affect the peak stress of the RCR combination, and the speed of stress reduction after the peak of the RCR combination is influenced by the parameter m. The coal elastic modulus exerts greater influence on the bearing capacity of the RCR combination than the rock elastic modulus. When the elastic modulus of rocks increases from 10 to 25 GPa and that of coal increases from 2 to 5 GPa, the peak stress of the RCR combination increases by 9.87% and 8.97%, respectively.

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Super-critical CO2 saturation-induced mechanical property alterations in low rank coal: An experimental study

Cited by 89 publications

References 29 publications

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

In‐situ temperature‐depth profile evaluation of South African unmineable coal seams to determine CO₂ sequestration potential

Study on damage and failure characteristics of loaded gas‐bearing rock–coal–rock combination structures

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Super-critical CO2 saturation-induced mechanical property alterations in low rank coal: An experimental study

Cited by 89 publications

References 29 publications

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

Effect of Coal Rank on Various Fluid Saturations Creating Mechanical Property Alterations Using Australian Coals

In‐situ temperature‐depth profile evaluation of South African unmineable coal seams to determine CO2 sequestration potential

Study on damage and failure characteristics of loaded gas‐bearing rock–coal–rock combination structures

Contact Info

Product

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In‐situ temperature‐depth profile evaluation of South African unmineable coal seams to determine CO₂ sequestration potential