| 鄂尔多斯盆地南部延长组层序地层格架中烃源岩特征及控制因素 |
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| 引用本文： | 周翔,何生,陈召佑,刘萍,王芙蓉.鄂尔多斯盆地南部延长组层序地层格架中烃源岩特征及控制因素[J].地球科学,2016,41(6):1055-1066. |
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| 作者姓名： | 周翔 何生 陈召佑 刘萍 王芙蓉 |
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| 作者单位： | 1.中国地质大学构造与油气资源教育部重点实验室，湖北武汉 430074 |
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| 基金项目： | 国家科技重大专项项目2016ZX05005-001高等学校学科创新引智计划资助项目B14031 |
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| 摘 要： | 三叠系延长组是鄂尔多斯盆地中生界重要的含油气层位，属典型的岩性油藏，具有含油层位多、成藏关系复杂的特点，其中烃源岩发育特征对岩性油藏分布具有重要的控制作用.基于露头和测井资料，将鄂尔多斯盆地南部延长组自下而上划分为SQ1、SQ2和SQ3三个三级层序，研究了层序地层格架控制下烃源岩的发育特征及其控制因素.研究结果表明:主力烃源岩赋存于湖侵体系域，以长7段为代表，属湖泊扩张至最大湖泛期物源补给欠补偿时半深湖-深湖相沉积，缺乏大量陆源碎屑注入而发育腐泥组占绝对优势的高有机质丰度烃源岩.高位体系域亦发育有烃源岩，如长9段和长6-4+5段，属最大湖泛期后物源补给超过基准面上升而向湖盆推进的滨湖相、浅湖相沉积，陆源碎屑输入致其表现为腐植型占优势且具较高有机质丰度的烃源岩.油源对比显示延长组油源主要来自晚三叠世延长组最大湖泛期形成的长7段湖侵体系域，说明不同体系域烃源岩对延长组油藏的贡献存在差异.层序地层沉积动力背景下体系域可容纳空间垂向与侧向变化，不仅决定体系域内部沉积相类型展布，更直接控制体系域内烃源岩有机质丰度和类型.研究层序地层格架中不同体系域内烃源岩赋存的差异性，有助于在层序沉积背景下预测和评价盆地内烃源岩分布规律.
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| 关 键 词： | 鄂尔多斯盆地南部 三叠系延长组 层序地层学 烃源岩 石油地质 |
| 收稿时间： | 2015-12-12 |
Characteristics and Controlling Factors of Source Rocks in Yanchang Formation Sequence Framework,Ordos Basin |
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| Abstract: | The Triassic Yanchang Formation, the most important oil and gas horizon in Ordos Basin, is a typical lithologic reservoir characterized by mass oil-bearing and complex hydrocarbon accumulation, and characteristics of its source rocks are the main controlling factors of lithologic reservoir distribution. Based on outcrops and well log data, this paper divides the Yangchang Formation into three sequences including SQ1, SQ2 and SQ3 upwards to research the characteristics and controlling factors of source rocks within sequence framework. The results show that the primary source rock occurred in expansive system tract, and is characterized by Chang7 source rock belonging to semi-deep lake and deep lake underfilled type deposits during the lake maximum flood period; meanwhile, the sapropel-type kerogen source rocks with a higher organic matter abundance are dominant due to the lack of terrigenous clastic supply. There are also source rocks in highstand system tract such as Chang9 and Chang6 to Chang 4+5 belonging to the deposition of lake-shore, shallow lake facies, in which terrigenous clastic supply makes humic type source rock dominant also with a relative high organic matter abundance. The crude oil of Yanchang Formation in the study area is primarily from Chang7 within expansive systems tract during maximum flooding period of Late Triassic according to crude oil correlation, which implies that contributions of source rocks in different system tracts to Yanchang reservoir vary. The vertical and lateral change of accommodation under sequence stratigraphic sedimentary dynamics setting not only decides the distribution of sedimentary facies types, but also directly controls the abundance and type of organic materials within system tracts. The difference of source rock occurrences between system tracts in sequence framework facilitates prediction and evaluation of distribution laws of source rocks in the sedimentary setting of basin. |
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