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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。
The pore structure characteristics of tectonic coal were analyzed by mercury intrusion test and cryogenic liquid nitrogen adsorption experiment. The influence of porosity on the gas production characteristics of coalbed methane was discussed in combination with the ground CBM extraction test. In this paper, the pores in coal are divided into four types: adsorbed pores (pore size less than 10nm), free pores (pore size 10 ~ 100nm), diffusion pores (pore size 100 ~ 1 000nm) and seepage pores (pore size greater than 1 000nm). It is found that the pore system of tectonic coal shows a “polarization” distribution, ie, adsorption pores, free pores, large seepage pores and few diffusion pores. The pore types are mainly dominated by cylindrical pores, ink bottle-shaped pores and slit plate shapes . The pore system of tectonic coal determines the large amount of gas reserves in coal, but the poor production and transportation channels lead to fluctuating gas-producing characteristics during the drainage of ground coalbed methane wells.