TY - JOUR
T1 - Evolution and analysis of gas sorption-induced coal fracture strain data
AU - Liu, Zhanghao
AU - Liu, Jishan
AU - Pan, Pengzhi
AU - Elsworth, Derek
AU - Wei, Mingyao
AU - Shi, Rui
N1 - Funding Information:
This work was supported by the State Key Research Development Program of China (Grant No. 2017YFC0804203), Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. QYZDB-SSW-DQC029) and the Australian Research Council under Grant DP200101293. These supports are gratefully acknowledged.
Funding Information:
This work was supported by the State Key Research Development Program of China (Grant No. 2017YFC0804203), Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. QYZDB-SSW-DQC029) and the Australian Research Council under Grant DP200101293. These supports are gratefully acknowledged.
Publisher Copyright:
© 2020, The Author(s).
PY - 2020/4/1
Y1 - 2020/4/1
N2 - Although coal swelling/shrinking during coal seam gas extraction has been studied for decades, its impacts on the evolution of permeability are still not well understood. This has long been recognized, but no satisfactory solutions have been found. In previous studies, it is normally assumed that the matrix swelling/shrinking strain can be split between the fracture and the bulk coal and that the splitting coefficient remains unchanged during gas sorption. In this study, we defined the fracture strain as a function of permeability change ratio and back-calculated the fracture strains at different states. In the equilibrium state, the gas pressure is steady within the coal; in the non-equilibrium state, the gas pressure changes with time. For equilibrium states, the back-calculated fracture strains are extremely large and may be physically impossible in some case. For non-equilibrium states, two experiments were conducted: one for a natural coal sample and the other for a reconstructed one. For the fractured coal, the evolution of permeability is primarily controlled by the transition of coal fracture strain or permeability from local matrix swelling effect to global effect. For the reconstituted coal, the evolution of pore strain or permeability is primarily controlled by the global effect.
AB - Although coal swelling/shrinking during coal seam gas extraction has been studied for decades, its impacts on the evolution of permeability are still not well understood. This has long been recognized, but no satisfactory solutions have been found. In previous studies, it is normally assumed that the matrix swelling/shrinking strain can be split between the fracture and the bulk coal and that the splitting coefficient remains unchanged during gas sorption. In this study, we defined the fracture strain as a function of permeability change ratio and back-calculated the fracture strains at different states. In the equilibrium state, the gas pressure is steady within the coal; in the non-equilibrium state, the gas pressure changes with time. For equilibrium states, the back-calculated fracture strains are extremely large and may be physically impossible in some case. For non-equilibrium states, two experiments were conducted: one for a natural coal sample and the other for a reconstructed one. For the fractured coal, the evolution of permeability is primarily controlled by the transition of coal fracture strain or permeability from local matrix swelling effect to global effect. For the reconstituted coal, the evolution of pore strain or permeability is primarily controlled by the global effect.
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U2 - 10.1007/s12182-019-00422-z
DO - 10.1007/s12182-019-00422-z
M3 - Article
AN - SCOPUS:85078628627
SN - 1672-5107
VL - 17
SP - 376
EP - 392
JO - Petroleum Science
JF - Petroleum Science
IS - 2
ER -