不同变形程度煤的吸附时间及其影响因素

Adsorption time of coals with different degrees of deformation and their influencing factors

基于沁水盆地南部长治和安泽区块103口煤层气井的实测资料，探讨不同变形程度煤的吸附时间及其影响因素。研究结果表明，不同变形程度煤的孔隙结构导致其解吸特征具有较大差异。随着煤变形程度的增加，吸附时间迅速减小。相对于未变形煤和弱变形煤，强变形煤由于裂隙和大、中孔隙发育较多且连通性较好，导致甲烷运移距离较短，解吸速率较大且解吸量急剧增加，吸附时间显著减小；解吸后期，强变形煤由于小孔隙和微孔隙发育，吸附能力增强且连通性较差，导致甲烷解吸和运移的难度增大，解吸速率迅速下降，而弱变形煤和未变形煤受孔隙、裂隙特征和取心煤样几何形态的共同影响，解吸速率变化较小且吸附时间较长。依据煤层气井排采数据可知，煤的变形程度差异是导致煤层气井产气量不同的主要原因，明确煤的吸附时间可以为预测煤层气井的产气量提供依据。

Based on measured data of103CBM wells in Changzhi and Anze Block in Southern Qinshui Basin,the adsorption time of coals with different degrees of deformation and its influencing factors were discussed,which can provide guidance for production prediction of coalbed methane well.The pore structures of coals with different degrees of deformation result in great difference in their desorption characteristics.As the degree of coal deformation increases,the adsorption time decreases quickly.In contrast to undeformed coal and weakly deformed coal,the desorption rate of strongly deformed coal is higher,and its amount of desorption increases sharply and the adsorption time become shorter because of well-developed fractures,macropores and mesopores which provide better connectivity and shorter migration path.In the late of desorption,the well-developed small pores and micropores of strongly deformed coal have strong adsorption ability and poorer connectivity,which increases difficulty in methane desorption and migration and therefore the desorption rate reduces markedly.However,the desorption rate of undeformed coal and weakly deformed coal changes slightly and their adsorption time is very long,which is the integrated result influenced by pore and fracture characteristics and geometry shape of coal core.Based on the drainage date of coalbed methane well,it can be drawn that the difference of coal deformation is the major reason for the production change of coalbed methane well.The adsorption time of coal can provide guidance for produc tion prediction of coalbed methane well.