河北南部石炭—二叠纪煤层气烃源岩特征

Permo-Carboniferous CBM Source Rock Features in Southern Hebei Area

河北南部地区石炭—二叠系煤层煤种丰富,峰峰、邯郸矿区煤层的宏观煤岩类型以半亮煤和半暗煤为主;显微煤岩类型为微镜煤、微镜惰煤及微暗煤;煤的结构以细、中宽条带状结构为主,在半亮煤和半暗煤中最多;有机显微组分以镜质组最高,一般可占50%～91%,惰质组占10%～35%,壳质组含量一般不超过5%,对煤层气来说,这是比较有利的烃源条件;区内大淑村矿2煤的矿物质含量最低,其煤的吸附能力较其它矿区高;主煤层镜质组最大反射率具有北高南低的分布规律,揭示了煤的生烃强度具有由南向北逐渐增高的趋势。该区煤层气源岩不仅影响煤的生烃能力,还影响着煤层对甲烷的吸附能力和煤层气的开采能力。

The Permo-Carboniferous coal seams in southern Hebei area have various coal ranks. Coal maerolithotypes of Handan mining area coal seams are mainly semibright coal and semidull coal. Macerals are vitrite, vitrinertite and durite. Coal textures are mainly fine, medium width banded, especially in semibright and semidull coals. Organic macerals is mainly vitrinite, generally account for 50%-91%, inertinite 10%-35%, exinite usually not more than 5%. For CBM, those are rather favorable source terms. The No.2 coal in Dashucun coalmine has lowest mineral matter content; coal adsorptivity is higher than other mine areas. Main coal seam maximum reflectance of vitrinite has a ＂high north, low south＂ distribution pattern, revealed a trend of coal hydrocarbon generating intensity increasing from south to north. Thus the CBM source rock not only impacts coal hydrocarbon generating capability, but also coal seam methane adsorptivity and CBM exploitability.