东道海子凹陷周缘构造油气源对比及勘探潜力分析

通过研究东道海子凹陷烃源岩抽提物及周边构造原油的地球化学特征，总结了研究区内三套主要烃源岩产物在稳定碳同位素、Pr/Ph、甾烷相对组成等方面存在的差别。油源对比结果表明:研究区原油碳同位素相对较轻，Pr/Ph普遍小于3，甾烷相对组成中以C₂₉含量最高，C₂₈含量次之，整体上符合二叠系平地泉组烃源岩产物的特征，并在滴南凸起的西部及中部存在石炭系烃源岩产物不同程度的少量混入。通过各项生物标志化合物成熟度参数及甲基菲指数分析了原油成熟度的差异，并借助前人研究成果将其换算为统一的成熟度参数R_o，从而得出了不同演化阶段生成原油的分布范围。平地泉组烃源岩生烃高峰期的产物未能大规模运移至构造高部位成藏，可能尚赋存于凹陷深部及斜坡区域，东道海子凹陷斜坡区域低幅度构造及岩性圈闭是寻获生烃高峰期产物的有利目标。

Oil-Gas Source Correlation around Dongdaohaizi Sag for Hydrocarbon Exploration Potential Analysis

Geochemistry characteristics of the source rock and oil from Dongdaohaizi Sag are studied,such as carbon isotope,Pr/Ph and sterane relative composition,to analyse the hydrocarbon origin and accumulation.The oil-source correlation revealed that:The oil comes mainly from Permian source rock of Pingdiquan Formation,but in the western and central area of Dinan Uplift,the oil is mixed by materials from carboniferous source rock.The maturity of oil is studied through biomarker parameters and alkylphenanthrene index (MPI),as well as the source rock evolution,which indicated that the oil was generated in different stages of source rock evolution.The source rock of Pingdiquan Formation is mature,but oil generated in the peak period of hydrocarbon generation has not migrated into the structural high,which still lies in the slope region of the sag possibly.As a conclusion,low-amplitude structures or the lithology traps in the slope region of Dongdaohaizi Sag is probably a good choice for exploring the oil generated in the peak period of hydrocarbon generation.