海相页岩与海陆过渡相页岩吸附气量主控因素及其差异性

摘要

以黔北地区下寒武统牛蹄塘组海相页岩和南华北地区下二叠统太原-山西组海陆过渡相页岩为研究对象,分析页岩有机地化、储层、吸附气量特征,进而研究页岩吸附气量影响因素及其差异性.研究结果表明:页岩有机碳含量大于2％,两者均为优质的烃源岩;但有机碳含量相差甚大.牛蹄塘组页岩矿物组成主要为石英,其次为黏土矿物,而太原-山西组页岩以富集黏土矿物为特征.牛蹄塘组页岩比表面积和吸附气量大于太原-山西组页岩;而总孔体积和平均孔径均小于后者.页岩岩石组成与吸附气量之间的关系如下:牛蹄塘组页岩TOC与吸附气量呈正相关关系且TOC是吸附气量的主要影响因素;而太原-山西组页岩TOC与吸附气量之间关系不明显.牛蹄塘组页岩石英与吸附气量呈正相关性,其原因是石英为生物成因,伴随有机质富集;而太原-山西组页岩石英与吸附气量具有负相关性,其原因为TOC和黏土矿物随石英的增加而减少,且TOC、黏土矿物与吸附气量呈正相关关系.牛蹄塘组页岩伊利石和太原-山西组页岩黏土矿物均与吸附气量具有正相关性,原因为黏土矿物吸附有机质且黏土矿物中各组分发育大量孔隙.%The marine shale in Lower Cambrian Niutitang formation,Qianbei area and the transitional facies shale in Lower Permian Taiyuan and Shanxi Formation,the southern North China area was taken as the research object.The characteristics of organic geochemistry,reservoir and adsorbed gas of shale were analyzed,and the influence factor of adsorbed gas of shale and the differences of influence factor were studied.The results show that the organic carbon content of shale is greater than 2％ and both of them are good source rocks.But the difference of organic carbon content is very large.The mineral of Niutitang formation shale is mainly composed of quartz,followed by clay minerals.But the Taiyuan and Shanxi Formation shale is characterized by the enrichment of clay minerals.The specific surface area and the adsorbed gas of Niutitang formation shale is greater than that of Taiyuan and Shanxi Formation shale.However,the total pore volume and average pore diameter are both smaller than the latter.The relationship between shale rock formation and adsorbed gas is as follows.The relationship between TOC of Niutitang formation shale and adsorbed gas is positively correlated and TOC is the main influence factor of adsorbed gas.But TOC of Taiyuan and Shanxi Formation shale has little effect on adsorbed gas.There is a positive correlation between quartz and adsorbed gas in Niutitang formation shale.The reason is that the quartz is biogenetic,along with the enrichment of organic matter.However,quartz in Taiyuan and Shanxi Formation shale and adsorbed gas have a negative correlation.The reason is that TOC and clay minerals decrease with the increase of quartz and that TOC,clay minerals and adsorbed gas are positively correlated.Illite of Niutitang formation shale,clay minerals of Taiyuan and Shanxi Formation shale and adsorbed gas have positive correlation.The reason is that organic matter is adsorbed by clay minerals and that a large number of pores are developed in clay minerals.