【摘要】 生物气源岩生成的是以甲烷为主的天然气,而生油岩生成的主要是液态烃,后者的研究与评价方法已不完全适用于生物气,因而不能用有机碳含量、烃含量等指标来评价生物气源岩。为此建立了一套生物气源岩的综合评价方法:①用Ro来反映演化指标,生物气源岩沉积在未—低熟演化阶段,其Ro<0.7%;②以nC21-/nC22+来反映生源指标,对于生物气源岩来说,富氢、富氧混源输入是有利的;③以姥鲛烷/植烷比值(Pr/Ph)作为环境指标,Pr/Ph低是还原环境加强的结果;④以主峰碳数作为降解指标,奇数碳为主峰的生物气源岩产气率高,偶数碳为主峰的生物气源岩产气率较低。该综合评价方法适用于柴达木、莺—琼、河套和松辽等盆地。更多还原

【Abstract】 Hydrocarbons generated by biogas source rocks are dominated by methane,while that generated by oil source rocks are mainly of liquid hydrocarbons.The study and evaluation procedures for the latter are not completely applicable to the former,thus indexes such as TOC and hydrocarbon content cannot be applied to evaluate biogas source rocks.A set of integrated evaluation procedures are presented for biogas source rocks: a.Ro is used as an index of evolution,with a Ro<0.7% indicating biogas source rocks in premature to low mature stages of evolution;b.nC21-/nC22+ is taken as an index of organic matter sources,with hydrogen-rich and oxygen-rich mixed input being favorable;c.Pr/Ph ratio is used as an environment index,with low Pr/Ph ratio indicating an enhanced reducing environment;d.the carbon number at the main peak is taken as a degradation index,with an odd carbon number indicating high gas yield of biogas source rocks while an even carbon number indicating low gas yield of biogas source rocks.This integrated evaluation procedure is applicable to basins such as Qaidam,Yingqiong,Hetao and Songliao.更多还原