沧东次凹沙河街组成烃环境及生排烃特征

Hydrocarbon-forming Environment and Eneration-exhaustion Characteristic of Shahejie Formation in Cangdong Subsag

沧东次凹沙河街组主要发育低熟烃源岩,为了明确该区低熟油的勘探潜力,围绕低熟与成熟烃源岩生烃物质及生排烃机理的差异性,进一步深化了成烃环境及生排烃的特征研究,并得到以下结论:沧东次凹以咸化-半咸化湖强还原相为主,成烃环境最好;盐山次凹沙一段为咸化-半咸化湖强还原相,成烃环境有利;南皮次凹以淡-半咸化湖还原相为主;吴桥次凹为淡-微咸化湖还原-弱还原相,成烃环境较差。同时,利用含油饱和度开展了生排烃研究,证实了沙河街组未熟-低熟烃源岩具有明显的生排烃过程,沙一段排烃门限浅于沙三段,其中沧东次凹沙河街组烃源岩具有较强的排烃能力。

In Shahejie formation,Cangdong subsag,immature-low mature hydrocarbon source rocks is mainly developed.By studying the difference of hydrocarbon generating and generation-exhausting mechanism between immature and mature source rock,hydrocarbon-forming environment and generation-expulsion characteristic,it could be confirmed the difference of hydrocarbon precursor under the hydrocarbon-forming environment in different subsag; Based on the study of oil saturation,it is obvious that the immature-low mature hydrocarbon source rocks in shahejie formation has hydrocarbon generation-exhausting process,and the hydrocarbon-generating threshold of sha 1 formation is lower than that of sha 3 formation.The result has guiding significance for immature oil exploration and selection in this area.