渤海湾盆地烃源岩有机-无机相互作用对生烃的影响

Effects of Organic-inorganic Interaction on Hydrocarbon Generation of Source Rocks in Bohai Bay Basin

以渤中19-6气田为例,以烃源岩为研究对象,开展有机-无机相互关系研究,厘清渤中19-6构造带烃源岩特征及有机-无机相互作用对生烃成气的影响。30余口井泥岩样的有机地球化学、无机地球化学、古生物等分析结果表明,渤中19-6构造带及周缘次洼古生物以被子类和裸子类高等植物为主,形成了以腐殖型无定形体占绝对优势的Ⅱ2型烃源岩;渤中19-6构造带黏土矿中伊利石占绝对优势,在黏土矿表面通过物理吸附和化学键作用富集了大量腐殖型无定形体并经加氢改造,后期在伊利石的影响下,烃源岩主要发生脱羧反应,热裂解形成大量短链烃类,产烃量大大增加,进而富集形成现今凝析油气广泛分布的特征。

In this paper,taking the Bozhong 19-6 gas field as an example and source rocks as the research object,the organic-inorganic interaction is studied to clarify the characteristics of source rocks in the Bozhong 19-6 structural belt and the effect of organic-inorganic interaction on the hydrocarbon generation and gas generation.Mudstone samples from more than 30 wells are selected for organic geochemistry,inorganic geochemistry,paleontology and other series analysis.The results show that,the source rocks in the study area are mainly partial humic organic matter,the paleontology is dominated by the higher plants of angiosperms and gymnosperms,and the humic amorphous forms are the dominant kerogen.The illite is the dominant clay mineral in the Bozhong 19-6 structural belt.A large number of humic amorphous forms have been enriched by physical adsorption and chemical bond bridging,and the organic matter is hydrogenated by clay minerals.In the late period,under the effect of illite,the source rocks mainly undergo decarboxylation reaction and thermal cracking to form a large number of short-chain hydrocarbons.Under the action of illite,the hydrocarbon production increases greatly,and then enriches,forming the wide distribution of condensate oil and gas.