天文旋回在页岩油勘探及富有机质页岩地层等时对比中的应用  

Application of astronomical cycles in shale oil exploration and in high-precision stratigraphic isochronous comparison of organic-rich fine-grain sedimentary rocks

作　　者：石巨业 金之钧 刘全有 樊太亮[1] 高志前[1] 王宏语[1] SHI Juye;JIN Zhijun;LIU Quanyou;FAN Tailiang;GAO Zhiqian;WANG Hongyu(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China;Institute of Energy,Peking University,Beijing 100871,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]页岩油气富集机理与有效开发国家重点实验室,北京102206 [3]北京大学能源研究院,北京100871

出　　处：《地学前缘》2023年第4期142-151,共10页Earth Science Frontiers

基　　金：国家自然科学基金项目(42102150,U19B6003-01-02);中央高校基础研究经费支持项目“天文周期驱动下湖相烃源岩多尺度旋回与古气候响应(2-9-2020-032)”。

摘　　要：地球演化过程中存在着不同尺度旋回性,其时间跨度可以由一天至数亿年。地球轨道周期驱动的轨道尺度的沉积旋回,是目前定量化地层划分对比研究最好的时间尺度选择。富有机质页岩的连续性使得轨道尺度的天文旋回更容易保存,而米氏旋回的“时间内涵”是进行地层等时对比的有效手段,可以对富有机质页岩进行高精度的地层划分和对比。本文以中国东部渤海湾盆地东营凹陷页岩油勘探的主力烃源岩层段为例,利用地球轨道周期实现陆相富有机质页岩多尺度地层等时对比,相关研究具有重要的科学和页岩油勘探指导意义。以斜率作为地层划分与对比的基本单元,实现东营凹陷富有机质页岩六级层序等时对比,误差小于4万年。通过天文年代标尺的区域对比,明确东营凹陷页岩油高产层段时间为42.85~41.85 Ma,在E2-E4这3个长偏心率周期范围内,与斜率周期的高振幅段恰巧吻合,推测其与斜率周期驱动的纹层状页岩发育所导致的页岩油高产有关。地球轨道周期具有较高的时间分辨率且较容易识别,万年级的年代框架为陆相页岩高精度等时对比提供了可能,可为页岩油勘探中优质烃源岩层段预测提供精细年代框架。There are different scales of cyclicity in the Earth’s evolution,from one day to several hundred million years.Presently,the scale of the astronomical cycles controlled by the Earth’s orbit is one of the most suitable timescales for high-precision stratigraphic comparison.Astronomical signals are more likely present in the continuous succession of organic-rich shale,where the“precise periodicity”of Milankovitch cycles makes it feasible to achieve stratigraphic isochronal correlation therefore to allow high-precision comparison of organic-rich shale.In this paper,the main source rocks of the Shahejie Formation in Dongying sag,Bohai Bay Basin,eastern China are studied,and the multi-scale isochronal correlation of continental organic-rich shale is achieved by using the astronomical cycles,which demonstrates that the sixth-order sequence division and organic-rich shale comparison can be performed with an error of less than 40000 years by using the obliquity cycle as the basic unit.According to the results,the high-production shale formation in the Dongying sag is located at 42.8541.85 Ma near the E2 E4 long eccentricity cycles and coinciding with a high-amplitude obliquity cycle.It was hypothesized that the high-production shale is likely related to the obliquity-driven laminated shale that has high mobility and oil-bearing property.This result further demonstrates that the high-precision isochronal comparison of continental organic-rich shale using astronomical cycles can provide a high-precision chronological framework for the prediction of high-quality hydrocarbon source rocks.

关 键 词：旋回地层学 页岩油 细粒沉积岩 高频层序 米兰科维奇理论 天文年代表 

分 类 号：P539.2[天文地球—古生物学与地层学] P534.61[天文地球—地质学] P618.13