单相气体在低渗透煤层运移规律

Migration law of single phase gas under low permeability coal bed

为探讨温度和孔隙压力以及围压对低渗煤层渗透率的影响规律,采用辽宁工程技术大学"真三轴渗透仪",在不同温度和围压条件下,对煤层试样进行实时渗透率研究,试样为长方体,外观尺寸为50 mm×50 mm×100 mm。加温试验发现,煤渗透率存在门槛值温度,当温度达到门槛值后,其渗透率出现大幅度增加,与室温状态相比,渗透率增加33倍。在煤热破裂的门槛值温度区域,煤样渗透率同时具有孔隙压力门槛值,其渗透率在孔隙压力门槛值发生剧烈变化,出现拐点;继续增加温度脱离温度门槛值后迅速增加,孔隙压力对于渗透率的影响随之加强,随着围压的增大这种现象更为显著。

To discuss influencing regularity of temperature,pore pressure and confining pressure to low permeability coal bed,using true triaxial permeameter of Liaoning Technical University,the permeability of coal bed model was studied at the different temperatures and confining pressures.The model was rectangular solid,outside dimension: 50mm×50mm×100mm.Coal permeability exit in the threshold level temperature area under heightening temperature,when the temperature reached threshold level,permeability rised considerably.Compared with room temperature,the permeability increased 33 times.Coal model permeability had pore pressure threshold level under thermal cracking threshold level temperature area,in which permeability changed fiercely at the pore pressure threshold level and inflection point emerged.The permeability could increase rapidly after the temperature above the threshold level,and the influence of pore pressure on permeability increased,which was more remarkable at the increasing confining pressure.