石油与天然气地质 ›› 2005, Vol. 26 ›› Issue (1): 99-103,113.doi: 10.11743/ogg20050113

• 油气地质 • 上一篇    下一篇

双河油田陆架型扇三角洲的沉积机理及向上变粗层序的成因

张昌民, 尹太举, 张尚锋, 李少华, 淡卫东   

  1. 长江大学地球科学系, 湖北荆州, 434023
  • 收稿日期:2004-12-05 出版日期:2005-02-25 发布日期:2012-01-16
  • 基金资助:

    湖北省教育厅重大项目(2000E0105)

Sedimentary mechanism of shelf-type fan delta and genesis of coarsening-upward sequence in Shuanghe oilfield

Zhang Changmin, Yin Taiju, Zhang Shangfeng, Li Shaohua, Dan Weidong   

  1. Department of Geosciences, Yangtze University, Jingzhou, Hubei
  • Received:2004-12-05 Online:2005-02-25 Published:2012-01-16

摘要:

双河油田核桃园组第三段扇三角洲具有陆架型扇三角洲的特点,单层呈正韵律而总体呈现反旋回的地层层序。这种层序既不是典型的河道沉积(正粒序)也不是典型的河口坝沉积(反粒序),它是在湖底坡降较缓的陆架型扇三角洲条件下,由河道进入湖盆的轴向射流所形成的沉积体。轴向射流的水流能量和速度沿着轴向向前方和两侧逐步衰减,所携带的沉积物的粒度随着水流能量的减弱而变细,沉积物的厚度变薄,逐步由水下分流河道演变成为一个坝状堆积物,形成分流河口的河口坝沉积。河口坝前缘沉积物连片,形成席状砂。河口坝实际上是河流入湖后形成的以河口坝为主的一系列微相组成的复合体,主要包括坝核、坝侧缘、坝边缘、坝前缘、席状砂和坝间6个微相类型。河道的主流线或河道的位置发生迁移时,导致砂坝垂向加高并产生横向迁移,从而形成了丰富的地层层序样式。

关键词: 扇三角洲, 地层层序, 沉积模式, 过程响应机制, 双河油田

Abstract:

Fan deltas in the 3rd member of Hetaoyuan Formation in Shuanghe oilfield have the characteristics of shelf-type fan deltas, where the strtigraphic sequences, as a whole, are developed in anticyclic sequences, but the single layer appear to be in positive rhythm. This kind of sequences are neither typical fluvial deposits, nor typical river mouth bar deposits. They are deposited as a result of axial efflux from river channel to lake basin under the condition of shelf-type fan delta with midly sloping lake floor. The energy and speed of axial efflux gradually decrease toward the axial direction and both sides, and the grain sizes of sediments decrease along with lowering of water flow energy, the deposits get thinner and evolve from subaquous distributary channel deposits into distributary mouth bar deposits. The deposits in the leading edge of mouth bar spread out and become sheet sand. In fact, the river mouth bar is a complex composed mainly of river mouth bar,and 6 microfacies, including core, lateral margin, margin,front edge,sheet sand and interbar. The bars get higher vertically and migrate laterally when the main stream line or location of channel migrate, resulting in plenty of sequence patterns.

Key words: fan delta, stratigraphic sequence, mode of deposition, process response mechanism, Shuanghe oilfield

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