Dimensional analysis and prediction of coal fines generation under two-phase flow conditions

Bai, Tianhang; Chen, Zhongwei; Aminossadati, Saiied M.; Li, Ling; Liu, Jishan; Lu, Hang

doi:10.1016/j.fuel.2017.01.040

Cited by 38 publications

(27 citation statements)

References 28 publications

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“…In this concern, it can be inferred that larger coal fines settled down prior to smaller ones, and were more difficult to be removed when the flow was reestablished. This indicates that by avoiding frequent well shut-in, coal fines caused permeability loss can be minimized, which is consistent with our previous finding (Bai et al, 2016;Bai et al, 2017). Fig.…”

Section: Permeability Evolutionsupporting

confidence: 93%

“…More coal fines are generated as the pressure gradient increased. We also conducted two-phase flow simulations (Bai et al, 2016;Bai et al, 2017). We find that two-phase flow generates more coal fines compared to single-phase flow.…”

Section: Accepted Manuscript 1 Inmentioning

confidence: 86%

“…During the CSG production process, when different flow regimes take place (e.g. single-phase flow and two-phase flow) (Bai et al, 2017;Wang et al, 2017), coal fines may plug coal cleats and/or deposit in cleats during the migration process, deteriorating coal permeability. This results in significant drop in the gas productivity (Magill et al, 2010;Palmer et al, 2005).…”

Section: Accepted Manuscript 1 Inmentioning

confidence: 99%

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Experimental investigation on the impact of coal fines generation and migration on coal permeability

Bai

Chen

Aminossadati

et al. 2017

Journal of Petroleum Science and Engineering

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Measurements of the coal fines production and the impact of these fines on the permeability of two coals from the Bowen Basin, Australia, were performed at different flow conditions (single-phase water or gas, two-phase water and gas) and pressure conditions. The fines collected from each coal samples ranged in size from 1 µm to 14 µm. For both coal samples, during the first 50 hours, the permeability decreases from 0.005 mD and 0.048 mD by 60.9% and 85%, respectively, followed by gradual decline with fluctuations. By the end of water injection, the permeability drops by 88% and 89%, respectively. This phenomenon is attributed to the counteraction between formation damage (cleats plugging and coal fines settlement) and breakthrough of coal fines from the samples (widened cleats). It was found that coal fines volumetric production is proportional to the third power of flow velocity once the flow paths for coal fines are established. The critical flow velocities of coal fines production for both samples were also obtained. For hydrophobic coal, water-drive-gas two-phase flow introduces abrupt permeability loss due to coal fines generation and migration. Furthermore, pauses (well shut-in) in the experiments cause slight permeability drops. A comparison between the two samples indicates that narrower and less connected cleating system results in more frequent coal fines generation and migration, resulting in significant permeability fluctuations with general decreasing trend. Tortuosity of the cleats can enhance the deterioration in permeability by coal fines behaviours. This study delivers fundamental understandings of coal fines generation and migration during the CSG production process, and useful guidelines are suggested to be implemented in the field to minimize production loss induced by coal fines behaviours.

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Section: Permeability Evolutionsupporting

confidence: 93%

Section: Accepted Manuscript 1 Inmentioning

confidence: 86%

Section: Accepted Manuscript 1 Inmentioning

confidence: 99%

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Experimental investigation on the impact of coal fines generation and migration on coal permeability

Bai

Chen

Aminossadati

et al. 2017

Journal of Petroleum Science and Engineering

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“…There are two factors for ignoring the gas effect. The first reason is the gas viscosity is much smaller than that of water (Bai et al 2017). Thus, the grab ability between gas and fine is much smaller than that between water and fine.…”

Section: Basic Assumptionsmentioning

confidence: 99%

Modeling of Coal Fine Migration During CBM Production in High-Rank Coal

Zhu

Peng

et al. 2017

Transp Porous Med

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During CBM (coalbed methane) production, the interaction of coal fracture surface with water flow commonly generates and starts coal fine flow. Part of flowing coal fines deposit in coal fracture system due to water production reduction and methane production increase. The fine sedimentation results in the reduction of coal permeability and well productivity. Despite the increasing awareness of the importance of fine migration, limited research has been carried out on the flow model of coal fine coupled with water and gas. In this paper, a flow model of coal fine is established coupled with water and gas flow, taking coal fine generation, migration and sedimentation process into consideration. Then, case simulations are conducted to illustrate effects of water production schedule, permeability performance and gas content on production performance in flow model. The simulation results indicate that methane rate with the lowest initial water rate is observed to have the highest production in late production period. This is mainly due to the reason that the low water flow cannot generate and start the flow of coal fine. Further, the case with high initial water production has faster gas and water flow rate, thus higher coal fine generation rates, which can improve well productivity at earlier production period. As water production declines quickly, both permeability and production performance decrease, which leads to the loss of well productivity. Meanwhile, higher gas content will lead to a faster water production decline at late production period. This indicates that a portion of coal fines plugged in the fracture as water production deceases and the CBM reservoir with high gas content should not adopt a high initial water production schedule.

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“…During the CSG production process, when different flow regimes take place (e.g. single-phase flow and two-phase flow) (Bai et al, 2017a), coal fines may plug coal cleats and/or deposit in cleats during the migration process, deteriorating coal permeability. This results in significant drop in the gas productivity (Magill et al, 2010;Palmer et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Integrated geomechanical, geohydraulic and geological (3G) study of coal fines generation and migration

Bai¹

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This study, considering the Geomechanical, Geohydraulic and Geological (3G) aspects, delivers fundamental understandings of coal fines generation and migration during the CSG production processes, and useful guidelines are suggested to be implemented in the field to minimize production loss induced by coal fines behaviours. v Declaration by author This thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis. I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, financial support and any other original research work used or reported in my thesis. The content of my thesis is the result of work I have carried out since the commencement of my higher degree by research candidature and does not include a substantial part of work that has been submitted to qualify for the award of any other degree or diploma in any university or other tertiary institution. I have clearly stated which parts of my thesis, if any, have been submitted to qualify for another award. I acknowledge that an electronic copy of my thesis must be lodged with the University Library and, subject to the policy and procedures of The University of Queensland, the thesis be made available for research and study in accordance with the Copyright Act 1968 unless a period of embargo has been approved by the Dean of the Graduate School.

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Dimensional analysis and prediction of coal fines generation under two-phase flow conditions

Cited by 38 publications

References 28 publications

Experimental investigation on the impact of coal fines generation and migration on coal permeability

Experimental investigation on the impact of coal fines generation and migration on coal permeability

Modeling of Coal Fine Migration During CBM Production in High-Rank Coal

Integrated geomechanical, geohydraulic and geological (3G) study of coal fines generation and migration

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