低渗煤层气藏气体KlinKenberg效应试验研究

Experiment on methane KlinKenberg effects in low coal reserve

采用低渗气体渗透率测定实验方法对东北地区的低渗煤样进行了煤层气K linKenberg实验。研究了不同围压和孔隙压下低渗煤样单相气体K linKenberg渗透率对气体渗透率的影响。发现在低渗煤样中气体K linKenberg效应存在具有普遍性,并且气体K linKenberg效应对气体渗透率贡献较大。K linKenberg效应的发生存在一个临界孔隙压力值,在本实验中,当孔隙压力大于1 Mpa时,K linKenberg效应消失。研究了饱和水和束缚水状态下低渗煤样气体K linKenberg效应变化规律。饱和水情况下,气体K linKenberg效应完全消失。在束缚水条件下,K linKenberg效应显著,且K linKenberg效应对气体渗透率的贡献比单相气体的贡献率大,并且出现K linKenberg效应的临界孔隙压力值比单相时的临界孔隙压力值大。本文研究结果对搞清煤层气在煤层中的K linKenberg流动规律,对实现低渗储层煤层气工业化开采具有参考价值。

The experiment method to measure low gas permeability rate by KlinKenberg effect is adopted for coal samples of northeast region of China to study gas slippage effect in coal reserve in this paper.The influence of single-phase KlinKenberg permeability on gas permeability in diversity confining pressure and pore pressure was analyzed.The experiment results showed that there were gas KlinKenberg slippage effects in low coal reserve.The gas KlinKenberg slippage effects has greater contribution to gas permeability rate.There was a critical porous pressure witch is about 1MPa in the experiment.When porous pressure is higher than 1MPa,the gas slippage effect completely disappears.The change rule of KlinKenberg effects under the saturation and bound water state in the low permeability was studied.In saturation water state,gas slippage effect completely disappeared.In bound water state,gas slippage effect appeared significantly compared to single-phase gas,large percentage of gas permeability rate induced by slippage effect to total gas permeability is larger than that in single-phase gas.Furthermore the critical porous pressure in bound water state is bigger then that in single-phase gas.The experiment results have values for study on gas flow in coal-bed and industrialization exploits of coal reserve.