大佛寺井田煤储层孔隙特征研究

Research on pore characteristics of coal reservoirs of Dafosi coal mine

为了研究大佛寺井田煤样孔隙特征,采集大佛寺井田4#上煤层煤样,选取4#上煤层宏观煤样组分中的镜煤和暗煤,分别利用压汞试验、扫描电镜和低温吸附等方法对其进行测试。结果表明:大佛寺井田4#上暗煤以微孔和小孔为主,4#上镜煤以小孔和中孔为主,4#上镜煤和4#上暗煤都具有比较强的煤层气吸附能力,4#上镜煤的孔隙连通性较好,以开放型孔为主,4#上暗煤则主要以半封闭型的孔隙为主。扫描电镜结果表明大佛寺井田4#上暗煤可观察到煤表面存在一定数量的次生孔隙,但是整体孔隙的连通性较差。但4#上镜煤相比于4#上暗煤孔隙发育较好,清晰可见煤中出现了多道微裂隙和碎屑状的镜质体。综合来看,大佛寺井田4#上暗煤有助于煤层气的聚集,相对于暗煤而言,4#上镜煤利于煤层气的解吸和开发。

In order to research the pore characteristics of the coal sample in Dafosi coal mine,we selected vitrain and durain samples of Dafosi No.4 upper coal,and made the mercury injection,scanning electron microscopy and low-temperature liquid nitrogen adsorption experiments.The results show that components of No.4 upper durain and No.4 upper vitrain mainly consist of the micropores and transition pores at Dafosi mine field,the No.4 upper durain and No.4 upper vitrain are all conducive forcoal bed methane adsorption and accumulation.The No.4 upper vitrain is mainly dominated by the open hole,while the No.4 upper durain is mainly dominated by a semi closed pores,so the pore connectivity of No.4 upper vitrain is better than No.4 upper durain.The scanning electron microscopy test results No.4 upper durain develops a small number of secondary porosity,but the connectivity of overall pores is poor,which indicates the good adsorption capacity of coalbed methane.Compared with No.4 upper durain,the pores of No.4 upper vitrain well developed,a large number of clastic vitrinite materials and fractures exist on the surface of No.4 upper vitrain parallel beddings,which indicates No.4 upper vitrain is favorable to the desorption and development of the coalbed methane.