超临界CO_2致裂后页岩渗透率变化规律及影响因素  

Dynamic permeability change of supercritical CO_2 fractured shale and its influencing factors

作　　者：刘国军[1,2] 鲜学福[1,2] 周军平[1,2] 赵源[1,2] 殷宏[1,2] 郭耀文[1,2] 谢爽 

机构地区：[1]重庆大学煤矿灾害动力学与控制国家重点实验室,重庆400044 [2]重庆大学资源及环境科学学院,重庆400044

出　　处：《煤炭学报》2017年第10期2670-2678,共9页Journal of China Coal Society

基　　金：国家重点基础研究发展计划(973)资助项目(2014CB239204);重庆市院士基金资助项目(CSTC2015jcyjys90001);重庆市国土局科技计划资助项目(KJ-2015040)

摘　　要：根据近几年兴起的无水压裂学术思想,采用超临界CO_2压裂后的裂隙页岩体试件(Φ100 mm×200 mm圆柱体试件),开展了不同体积应力和不同温度条件下CO_2渗流实验来模拟压裂后页岩气储层的渗透特性变化,揭示不同因素对裂隙页岩体渗透率的影响机理。实验结果表明:页岩吸附CO_2后渗透率降低;裂隙页岩体渗透率随有效应力的增加呈负指数关系减少;在CO_2超临界温度32~48℃的内页岩渗透率随温度升高而降低,而且渗透率对温度的敏感性也随着温度的升高越来越小;在低压阶段(1~3 MPa),Klinkenberg效应作用明显,在该阶段渗透率随着气体压力的增加而减少,当气体压力在3~5 MPa时,渗透率随气体压力的增加而增加;页岩储层对CO_2的渗透率受地温、地压以及其自身孔隙结构共同影响。Based on academic thought of non-aqueous fracturing proposed in recent years,the shale cylinder specimen of diameter 100 mm and length 200 mm was fractured by supercritical CO2 first,then it was used to conduct CO2 seepage experiment at different volume stress and temperature conditions,aiming at revealing the mechanism of permeability change in supercritical CO2 fractured shale and its influencing factors. The experimental results show that the permeability of fractured shale decreased due to the CO2 adsorption induced swelling. The permeability of fractured shale has a negative exponential relationship with effective stress. At the temperature range of 32-48 ℃,the permeability decreased with the increase of temperature,and the temperature sensitivity of permeability is also decreased with the increase of temperature. At the low pore pressure range（ 1-3 MPa）,Klinkenberg effect exhibits a significant influence on the permeability,which leads to the permeability decreases with the increase of pore pressure,when the pore pressure exceeds 3 MPa,permeability increases with the increase of pore pressure as the effective stress is the dominant influencing factor. Therefore,the permeability of shale gas reservoir is commonly affected by the multiple factors such as geotemperature,geo-stress and the pore structure of shale. Finally,the coupling relationship between shale permeabilityand geo-temperature,geo-stress field is established according to the experimental results.

关 键 词：裂隙页岩体 渗透率 有效应力 滑脱效应 气体压力 

分 类 号：P618.13[天文地球—矿床学] TD712[天文地球—地质学]