构造煤孔隙结构对煤层气产气特征的影响

Effect on CBM drainage characteristics of pore structure of tectonic coal

采用压汞实验和低温液氮吸附实验分析了构造煤的孔隙结构特征,结合地面煤层气抽采试验,探讨了孔隙对煤层气产气特征的影响。论文将煤中孔隙划分为4种类型：吸附孔隙（孔径小于10nm）、游离孔隙（孔径10-100nm）、扩散孔隙（孔径100-1 000nm）和渗流孔隙（孔径大于1 000nm）。研究发现构造煤孔隙系统呈＂两极化＂分布,即吸附孔隙、游离孔隙、渗流孔隙居多,扩散孔隙少;孔隙类型主要以圆筒形孔、墨水瓶形孔和狭缝平板形为主。构造煤的孔隙系统决定了煤中气体储集量大、但产出运移通道不畅,由此导致地面煤层气井排采过程中的波动产气特征。

By the mercury injection test and low temperature liquid nitrogen adsorption test,combined with ground coalbed methane（CBM） drainage test,the coal pore structure characteristics and the influence on CBM drainage characteristics were studied.The pores in coal are divided into four types：The adsorption pores （pore size 〈10nm） and free porosity （pore size 10-100nm）,diffusion porosity （pore size 100-1 000nm）,seepage pore （pore size〉1 000nm）.The tectonic coal pore system has polorization distribution,that is,the adsorption pores,the free pores and the seepage pores are dominant,and the diffusion pores are minor.The pore types are mainly the cylinder shaped hole,the ink bottle shaped hole and the slit flat.The pore system of tectonic coal determines the characteristics of the more gas reservoir accumulation and the not unobstructed output channel,which leads to the fluctuation characteristics of the gas drainage of CBM ground well.