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本文通过系统研究该区低熟油的物理化学特征,总结了低熟油的标志特征。在此基础上进行了精细的油岩对比,确定了济阳坳陷低熟油主要来自咸水—半咸水的沙四段和沙一段烃源岩。通过模拟实验和自然演化剖面对比研究发现,济阳坳陷的沙四段和沙一段烃源岩之所以在埋藏较浅的情况下形成了大规模的低熟油资源,有以下几方面的重要原因:①沙四段、沙一段烃源岩中存在富含藻类的有机质富集层,它是形成低熟油的物质基础;②富含有机酸、钾离子、铝离子的地层流体特征加速了粘土矿物的成岩演化,促进了低熟油的生成;③可溶有机质是形成低熟油的主要贡献者;④咸化环境有利于可溶有机质的保存。通过对其成油体系的剖析发现,低熟油成藏具有早生、早排、成藏期晚、运移距离短等特点,油藏展布受有效烃源岩体的控制,故低熟油的勘探应紧紧围绕低熟烃源岩体进行。
In this paper, we systematically studied the physicochemical characteristics of low-mature oil in this area and summarized the characteristics of low-mature oil. On this basis, a detailed comparison of oil and rock was carried out, and it was confirmed that the low-mature oil in the Jiyang Depression is mainly derived from the source rocks of Sha 4 and Sha 1 in brackish-brackish water. Through the comparison of the simulation experiment and the natural evolution profile, it is found that the reason why the source rocks of Sha 4 Member and Sha 1 Member in Jiyang Depression form large-scale low-mature oil resources under the condition of shallow burial has the following important reasons : ① There is a rich organic-rich layer of algae in the Sha-4 Member and the Sha-1 Member source rocks, which is the material basis for the formation of low-mature oil. ② The formation fluids rich in organic acids, potassium ions and aluminum ions accelerate the clay Diagenetic evolution of minerals promotes the formation of low-mature oil; ③ Soluble organic matter is the main contributor to the formation of low-mature oil; ④ The salinization environment is conducive to the preservation of soluble organic matter. Through the analysis of oil-forming system, it is found that the low-mature oil reservoirs are characterized by early, early drainage, late hydrocarbon accumulation and short migration distance. The reservoir distribution is controlled by effective source rock mass, Exploration should focus on low-maturity source rocks.