海相烃源岩有机质类型的“双重属性”初探——以安徽南陵——无为地区浅水台地相碳酸盐岩为例

Discussion on the Dual Property of Organic Matter Type in Marine Source Rock: A Case of Shallowing Platform Carbonate Rock in Nanling-Wuwei Area, Anhui

普遍认为海相烃源岩的生烃母质以菌藻类为主,有机质类型好,其生烃潜力也高。新的研究认为这一观点有待商榷。南陵—无为地区上古生界和中生界海相地层烃源岩有机质表现出"双重属性":反映母质来源的评价指标干酪根镜下鉴定和碳同位素组成显示为腐泥型特征,有机质类型好;而反映生烃能力的评价指标干酪根元素比和岩石热解等参数则表现出其生烃潜力整体只相当于Ⅲ型有机母质的水平。对于海相烃源岩不能一概以生源优劣来直接代替有机质的生烃能力。认识到腐泥型的有机质成烃降解率并不总是很高,这对于客观地评价浅水台地环境沉积的碳酸盐岩生烃潜力是非常重要的。

It is prevalently known that the presursor of marine hydrocarbon source rock is derived from bacteria and algae so as to good types of organic matter and good hydrocarbongenerating potential. However in recent years, this pointview of the single organic quality is still deliberative. The organic quality of Mesozoic and upper Paleozoic hydrocarbon source rocks in Nanling-Wuwei area inAnhui reveals a dual property. The data of kerogen microscopic analysis and carbon isotope show the type of sapropel kerogen while the data of kerogen elementary ratio and Rock-Eval, which are the parameters of the hydrocarbon-generating potential of the organic matter, indicate the equivalent Type- Ⅲ. It is not always suitable that taking the original source replaces the hydrocarbon-generating potential. The degradation ratio of sapropel kerogen is not always high, which is important to evaluate the potential of marine hydrocarbon source rock.