渤海湾盆地饶阳凹陷沙一下亚段古湖泊环境与烃源岩发育模式

发布时间：2018-06-28 00:02

本文选题：饶阳凹陷 + 沙一下亚段　；参考：《地球科学》2017年07期

【摘要】：学者们对饶阳凹陷烃源岩的研究已经取得了一些成果,但针对沙一下亚段烃源岩发育时期的古湖泊环境却缺乏系统的研究,忽略了湖泊环境这个控制烃源岩地球化学特征和时空展布的重要因素.通过对沙一下亚段烃源岩样品的古生物资料、有机地球化学、微量元素和同位素分析,恢复其古气候、湖泊古水深、古盐度、氧化还原条件和古生产力,综合这些影响因素建立了沙一下亚段优质烃源岩的发育模式.结果表明,沙一段下亚段(Es1下)的优质烃源岩多发育于湖侵体系域沉积期,气候正从干旱炎热向温暖潮湿转变,湖水深度约为2~14m,浪基面深度为7.5m;古盐度参数如Sr/Ba和B/Ga等都指示了沙一下亚段湖侵体系域沉积期属于咸水环境,形成了稳定的盐度分层,从而造成底层水处于稳定的缺氧条件,有利于有机质的保存;而稳定碳同位素和营养元素的分布特征都表明此阶段湖泊表层水体有较高的初始生产力.这样的古湖泊环境造成强还原咸水半深湖沉积的有机相分布较广,有利于优质烃源岩的发育.
[Abstract]:Some achievements have been made in the study of source rocks in Raoyang Sag, but there is no systematic study on the paleo-lake environment during the development of source rocks in the submember of Shahejie. The lacustrine environment is an important factor controlling the geochemical characteristics and temporal and spatial distribution of source rocks. The paleoclimate, paleo-water depth, paleosalinity, redox conditions and paleoproductivity of the source rock samples of the submember of the Lower Shahejie formation were restored through the analysis of paleoclimate, organic geochemistry, trace elements and isotopes. Based on these factors, the development model of high quality source rocks in the Shashi submember is established. The results show that the high quality source rocks of the lower submember of the first member of Shahejie (es 1) are developed during the deposition period of the transgressive system tract, and the climate is changing from drought and heat to warmth and humidity. The depth of lake water is about 2 ~ 14m and the depth of wave base surface is 7.5 m. The paleosalinity parameters such as Sr- / Ba and B / Ga indicate that the deposition period of the transgressive system tract in the submember of Sand belongs to the saltwater environment and forms a stable salinity stratification, resulting in a stable anoxic condition of the bottom water. The stable carbon isotopes and the distribution of nutrient elements indicate that the surface water of the lake has high initial productivity at this stage. This paleo-lacustrine environment resulted in a wide distribution of organic facies in strongly reduced brackish half-deep lake sediments, which is conducive to the development of high-quality hydrocarbon source rocks.
【作者单位】：中国石油大学地球科学学院;中国石油华北油田勘探开发研究院;中国地质大学构造与油气资源教育部重点实验室;中国石油大学;
【基金】：国家自然科学基金重大项目(No.41690134);国家自然科学基金项目(No.U1663210) 中国石油华北油田科技项目(No.HBYT-YJY-2014-JS)
【分类号】：P618.13

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