Study On Coalbed Methane Sorption Time In Different Ranks In Eastern Yunnan And Western Guizhou

Based on coal rank,maceral and industrial component of 21 coalbed methane blocks/mines in the country,this paper discusses the variation of coal rock sorption time and its relationship with various factors under different coal rank conditions.And the factors affecting the sorption time of the Laochang and the Enhong block in Eastern Yunnan and Western Guizhou Area and the Shizhuangnan block in Qinshui Basin were emphatically analyzed.The research shows that the coal rank is the main factor affecting the sorption time of coal rock.With the change of coal rank,the sorption time has a “U” type variation.In addition to coal rank,the vitrinite content and ash content also influence the coal rock sorption time as secondary factors.The coal rock sorption time was positively correlated with the vitrinite content and negatively correlated with the ash content.Based on the study of the influence factors of sorption time among different coal rank,combined with the change of permeability,the change law of fluid mobility of different coal rank are discussed,and the corresponding drainage dynamic curve is combined to discuss and formulate the drainage optimization strategy aimed at initial drainage speed control,which was adopted and applied to the Laochang and the Enhong block in Eastern Yunnan and Western Guizhou Area.The research shows that in the context of the low permeability of coal rock in China,combined with coal rock sorption time,the initial drainage speed control should emphasize the word “slow”,especially coal seams with shorter sorption time,which should more emphasize “slow” in order to fully expand the pressure drop funnel to achieve high and stable production.