In terms of the coal reservoir permeability of effective stress, coal matrix shrinkage and gas slippage,
we conduct the tests of gas permeability under constant confining pressure and effective stress, as well as illustrate
the cumulating method of permeability increment caused by the effects of gas slippage and coal matrix shrinkage.
The results show that under the constant confining pressure, gas slippage affecting coal permeability changes to
effective stress affecting it mainly. The change point increases with the increase of the confining pressure. The gas
slippage effect leads to high permeability under low confining pressure, but coal matrix expansion results in the
low value as confining and gas pressures increase. Combined with the drainage process of coalbed methane (CBM)
well, the permeability is divided into four change stages based on the above analysis about the three effects, which
can improve the change regulation understanding. Four stages are the downward phase under effective stress,
the conversion phase of effective stress-coal matrix contraction effect (mainly based on effective stress), the rising
stage of the effective stress-coal matrix contraction effect (mainly based on coal matrix contraction effect) and
the rising phase of coal matrix contraction-slippage effect (mainly based on slippage effect). Permeability of coal
reservoir during the process of drainage and production goes through four stages.
HE Ye1,2* (何也), FU Xuehai1 (傅雪海), LIU Aihua3 (刘爱华)
. Experimental Simulation on Dynamic Variation of the Permeability of High-Rank Coal Reservoirs[J]. Journal of Shanghai Jiaotong University(Science), 2017
, 22(6)
: 726
-732
.
DOI: 10.1007/s12204-017-1893-6
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