地学前缘 ›› 2012, Vol. 19 ›› Issue (1): 40-50.

• 论文 • 上一篇    下一篇

鄂尔多斯盆地西南缘晚三叠世前陆冲断活动控制的沉积层序特征

 张天舒, 吴因业, 郭彬程, 冯有良   

  1. 中国石油勘探开发研究院， 北京 100083
  • 收稿日期:2011-11-15 修回日期:2011-12-01 出版日期:2012-01-10 发布日期:2012-01-10
  • 作者简介:张天舒(1982—)，女，博士研究生,矿产普查与勘探专业。E-mail：zhangtianshu@petrochina.com.cn
  • 基金资助:

    中国石油天然气集团科学研究项目（0601011）

The characteristics of  Late Triassic depositional sequence controlled by foreland thrustfaulting in southwestern Ordos Basin.

  1. Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
  • Received:2011-11-15 Revised:2011-12-01 Online:2012-01-10 Published:2012-01-10

PDF (PC)

1259

摘要：

从鄂尔多斯盆地西部前陆盆地的构造演化特征入手，通过对鄂尔多斯西南缘前陆冲断带汭河—陇县—麟游露头剖面和前陆斜坡带延河剖面上三叠统延长组典型露头剖面的观测与对比，以及显微镜薄片分析，讨论了鄂尔多斯盆地西南缘前陆不同构造带在沉积层序演化、砂体展布及储层微观特征等方面的差异及主控因素。认为鄂尔多斯盆地西南缘延长组长10—长2下部油层组可划分为3个湖侵体系域和3个湖退体系域。沉积砂体集中发育在湖侵早期和湖退阶段。前陆冲断带近秦祁造山带物源区，坡度陡，砂体沉积受构造作用控制，发育近物源辫状河三角洲。三角洲快速入湖，砂体厚度大，砂岩粒度较大，岩屑、杂基含量较高，储层物性相对较差。前陆斜坡带距离北部阴山褶皱带物源较远，坡度缓，砂体沉积受湖岸线迁移控制，发育远物源曲流河三角洲。砂体展布范围大，沉积相变化频繁，砂岩粒度较小，杂基含量较低，后期成岩作用产生次生孔隙，可成为较好储层。

关键词: 鄂尔多斯, 前陆盆地, 延长组, 三角洲, 体系域

Abstract:

This study demonstrated the differences in depositional sequence evolution, sandbodies distribution and reservoir microstructure and their controlling factors in different structures of foreland in the southwestern Ordos basin. Detailed information has been acquired through the analyses of tectonic evolution of foreland basin in the southwestern Ordos basin, the observation and correlation between the outcrops from RuiheLongxianLinyou profile of Yanchang Formation in foreland thrust belt and the outcrops from Yanhe profile of Yanchang Formation in the foreland slope belt, and the analyses of thin sections of rocks. The main conclusions are as follows. Firstly, three transgressive system tracts and three regressive system tracts are divided from Chang 10 to the lower part of Chang 2 oil layers of Yanchang Formation in the southwestern Ordos Basin. Moreover, sands mainly distribute in the early transgression and the whole regression. Secondly, the foreland thrust belt is near the Qinqi fold orogenic belt provenance, and develops a steep slope. Consequently, the sedimentation of sandbodies is controlled by tectonization. Therefore, the characteristics of proximal provenance braided river delta front can be observed as follows. The braided river delta enters the lake swiftly, so the particle size of thick sandbodies is large. However, the content of detritus and matrix is high, for this reason, the physical property of reservoirs can be comparatively poor. Thirdly, foreland slope belt is far away from Yinshan fold belt provenance in the north, and develops a gentle slope. As a result, the sedimentation of sandbodies is controlled by the shoreline shift. Accordingly, the characteristics of distal provenance meandering river delta can be observed as follows. The sands spread wide, and the facies change frequently. Further, the particle size is small, and the content of matrix is low. Besides, diagenesis produces secondary interstices. As the above data show, good reservoirs can be formed.

Key words:  Ordos Basin, foreland basin, Yanchang Formation, delta, systems tract

中图分类号: