石油与天然气地质 ›› 2017, Vol. 38 ›› Issue (3): 457-466.doi: 10.11743/ogg20170305

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地镇原地区长81砂层组双坡折带的发现及其研究意义

王昌勇1, 张懿1, 林世国2, 郑荣才1, 魏亚琼1, 王海红3, 侯长冰3, 苟幸福3   

  1. 1. 成都理工大学 油气藏地质及开发工程国家重点实验室, 四川 成都 610059;
    2. 中国石油 勘探开发研究院 廊坊分院, 河北 廊坊 065007;
    3. 中国石油 长庆油田分公司 超低渗透第四项目部, 甘肃 西峰 745000
  • 收稿日期:2015-11-04 修回日期:2017-06-02 出版日期:2017-06-28 发布日期:2017-07-10
  • 第一作者简介:王昌勇(1981-),男,博士、副教授,沉积学及石油地质。E-mail:wangchangyong09@cdut.cn。
  • 基金项目:
    国家科技重大专项（2016ZX05007）。

Discovery of double slope breaks and its significance in Chang 81 sand group in Zhenyuan area,Ordos Basin

Wang Changyong1, Zhang Yi1, Lin Shiguo2, Zheng Rongcai1, Wei Yaqiong1, Wang Haihong3, Hou Changbing3, Gou Xingfu3   

  1. 1. State Key Laboratory for Oil and Gas Reservoir Geology and exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China;
    2. Langfang Branch, Research Institute of Petroleum Exploration and Development, PetroChina, Langfang, Hebei 065007, China;
    3. The Fourth Section of Ultra-low Permeability Reservoirs, Changqing Oilfield Company, PetroChina, Xifeng, Gansu 745000, China
  • Received:2015-11-04 Revised:2017-06-02 Online:2017-06-28 Published:2017-07-10

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摘要： 通过岩心观察和测井岩性解释，对镇原地区长8油层组岩石组合特征、沉积构造、沉积相及层序地层特征进行了详细研究，确定镇原地区长81砂层组主要发育一套具双坡折带的浅水辫状河三角洲沉积，湖岸线在坡折带之上数十千米范围内频繁迁移。坡折带主要根据测井资料和沉积构造特征进行识别。镇原地区长81砂层组坡折带主要受基底断裂控制，其成因与盆地西、南缘强烈的火山喷发和构造活动有关。长81沉积期研究区可划分为第一坡折带之上的台型平原（前缘）、双坡折带之间的中部斜坡和第二坡折带之下的下部斜坡3个地貌单元，这一古地貌特征控制了湖侵期和湖退期砂体在不同相带的分配模式。靠近物源一侧的台型平原（前缘），湖侵期砂体较为发育，而在湖退期则以泥、粉砂岩为主；离物源较远的中部斜坡相带，湖侵期砂体较薄，而湖退期发育较厚并且优先堆积于第一坡折带附近；远离物源的下部斜坡相带，任何时期内砂体都很少发育；枯水期，湖岸线迁移至第一坡折带附近，坡折带附近的砂体，可能因波浪和沿岸流的搬运和改造而具有“沿岸砂坝”的特征。

关键词: 浅水三角洲, 坡折带, 湖岸线, 长8油层组, 镇原地区, 鄂尔多斯盆地

Abstract: Through the detailed core observation and lithologic interpretation of logging data,rock association characteristics,sedimentary architectures,sedimentary facies and sequence stratigraphy of Chang 8 reservoir in Zhenyuan area were studied.The results show that a shallow braided-river delta sediments with two slope breaks was developed during the deposition Chang 81,and the paleo-shoreline moved frequently within tens of kilometers above the slope breaks.These slope breaks were mainly identified by logging and sedimentary architecture features.Slope breaks of Chang 81 sand group in Zhenyuan area were mainly controlled by basement faults affected by violent volcanic and tectonic activity in the southern and western Ordos Basin.During deposition of Chang 81,the study area can be divided into three geomorphology units,including platform-like plain (front) above the upper slope break,central-slope between the two slope breaks and lower-slope below the lower slope break.The distribution of sand body in transgression and regression stages was controlled by the ancient geomorphological features.The platform-like plain which was close to the provenance received more sandstone during transgression stage,and mudstone and siltstone deposited during regression stage.The central-slope that was farther from the provenance developed thicker sand bodies during lake transgression stage,while sands preferentially accumulated around the first slope during the lake regression stage.The lower-slope that was far away from the provenance developed small amount of sand bodies in anytime.The shoreline moved to the first slope in low water stand,and sand bodies around the slope break may feature "coastal sand bar" because of the transportation and transformation of waves and coastal current.

Key words: shallow-water delta, slope break, lake shoreline, Chang 8 reservoir, Zhenyuan area, Ordos Basin

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