TY - GEN
T1 - Experimental Study of Impact of Dewatering Induced Coal Fines on Coal Permeability
AU - Bai, Tianhang
AU - Chen, Zhongwei
AU - Aminossadati, Saiied M.
AU - Rufford, Thomas
N1 - Publisher Copyright:
© ASCE.
PY - 2017
Y1 - 2017
N2 - Coal fines are small coal particles produced during coal seam gas (CSG) production and may plug fluid flow paths, resulting in significant reduction in CSG productivity. This study aims to employ laboratory experiments to examine coal permeability variation induced by coal fines generation and migration during the dewatering stage. One coal sample from Bowen Basin, Australia, was tested under different pressure differences. The evolution of coal permeability and the amount of produced coal fines were monitored during the experiments. The pressure difference was increased from the initial 0.8 MPa to 1.5 MPa through 7 steps to investigate its impact on the characteristics of coal fines and the corresponding permeability change, and to obtain the critical velocities for a range of particle sizes. Every 5 mL effluent was collected and analysed in terms of particle size distribution and volume. The results revealed that for this sample, the sizes of coal fines ranged from 1 μm to 14 μm. Initially the coal permeability dropped dramatically due to excessive coal fines generation, with 74.1% reduction for the case of 0.8 MPa pressure difference, followed by gradual decline with fluctuations. It was observed that the production of large coal fine particles was accompanied by significant permeability fluctuations. This was attributed to the counteraction between formation damage (cleats plugging and coal fines settlement) and coal fines removal from the samples (widened cleats). Although no clear correlation between particle size and pressure difference was observed, the critical particle size was positively related to the flow velocity. The velocity followed parabolic fashion against the pressure difference. For this sample, keeping the differential pressure between 1.1-1.3 MPa can reduce the permeability damage induced by coal fines. This study delivers fundamental understandings of coal fines generation and migration behaviours during the dewatering stage, which can provide useful guidelines to implement effective dewatering strategies to minimize production loss induced by coal fines.
AB - Coal fines are small coal particles produced during coal seam gas (CSG) production and may plug fluid flow paths, resulting in significant reduction in CSG productivity. This study aims to employ laboratory experiments to examine coal permeability variation induced by coal fines generation and migration during the dewatering stage. One coal sample from Bowen Basin, Australia, was tested under different pressure differences. The evolution of coal permeability and the amount of produced coal fines were monitored during the experiments. The pressure difference was increased from the initial 0.8 MPa to 1.5 MPa through 7 steps to investigate its impact on the characteristics of coal fines and the corresponding permeability change, and to obtain the critical velocities for a range of particle sizes. Every 5 mL effluent was collected and analysed in terms of particle size distribution and volume. The results revealed that for this sample, the sizes of coal fines ranged from 1 μm to 14 μm. Initially the coal permeability dropped dramatically due to excessive coal fines generation, with 74.1% reduction for the case of 0.8 MPa pressure difference, followed by gradual decline with fluctuations. It was observed that the production of large coal fine particles was accompanied by significant permeability fluctuations. This was attributed to the counteraction between formation damage (cleats plugging and coal fines settlement) and coal fines removal from the samples (widened cleats). Although no clear correlation between particle size and pressure difference was observed, the critical particle size was positively related to the flow velocity. The velocity followed parabolic fashion against the pressure difference. For this sample, keeping the differential pressure between 1.1-1.3 MPa can reduce the permeability damage induced by coal fines. This study delivers fundamental understandings of coal fines generation and migration behaviours during the dewatering stage, which can provide useful guidelines to implement effective dewatering strategies to minimize production loss induced by coal fines.
UR - http://www.scopus.com/inward/record.url?scp=85026293333&partnerID=8YFLogxK
U2 - 10.1061/9780784480779.141
DO - 10.1061/9780784480779.141
M3 - 会议稿件
AN - SCOPUS:85026293333
T3 - Poromechanics 2017 - Proceedings of the 6th Biot Conference on Poromechanics
SP - 1135
EP - 1144
BT - Poromechanics 2017 - Proceedings of the 6th Biot Conference on Poromechanics
A2 - Dangla, Patrick
A2 - Pereira, Jean-Michel
A2 - Ghabezloo, Siavash
A2 - Vandamme, Matthieu
PB - American Society of Civil Engineers (ASCE)
T2 - 6th Biot Conference on Poromechanics, Poromechanics 2017
Y2 - 9 July 2017 through 13 July 2017
ER -