石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (4): 917-928.doi: 10.11743/ogg20220414

• 油气地质 • 上一篇    下一篇

深水重力流水道-朵叶体系形成演化及储层分布

李华(), 何幼斌, 谈梦婷, 冯斌, 葛稳稳, 孙玉玺, 于星   

  1. 长江大学 地球科学学院,湖北 武汉 430100
  • 收稿日期:2021-09-23 修回日期:2022-04-27 出版日期:2022-07-14 发布日期:2022-07-14
  • 作者简介:李华(1984—),男,博士、副教授,深水沉积。E?mail: 501026@yangtzeu.edu.cn
  • 基金资助:
    国家自然科学基金项目(41472096);国家科技重大专项(2017ZX05032-002-003);湖北省自然科学基金项目(2020CFB745);地质资源与地质工程一流学科开放基金项目(2019KFJJ0818010)

Evolution of and reservoir distribution within deep-water gravity flow channel-lobe system: A case study of the Ordovician Lashenzhong Formation outcrop at western margin of Ordos Basin

Hua Li(), Youbin He, Mengting Tan, Bin Feng, Wenwen Ge, Yuxi Sun, Xing Yu   

  1. School of Geosciences,Yangtze University,Wuhan,Hubei 430100,China
  • Received:2021-09-23 Revised:2022-04-27 Online:2022-07-14 Published:2022-07-14

摘要:

通过对鄂尔多斯盆地西缘奥陶系拉什仲组深水重力流沉积露头精细解剖,揭示深水重力流水道-朵叶体系演化规律,建立沉积模式,分析储层分布规律。研究表明:鄂尔多斯盆地西缘奥陶系拉什仲组重力流沉积单元包括复合水道、迁移水道、层状充填垂向加积水道、分支水道、近端及远端朵叶。沉积单元演化与重力流类型和能量密切相关。重力流爆发初期,碎屑流和浊流活跃,复合水道发育;当重力流能量降低,浊流占主导,伴随多期侵蚀-沉积作用,先后发育迁移水道和垂向加积水道;随着浊流的持续作用及能量逐渐衰减,分支水道、近端及远端朵叶依次发育。其中,复合水道可进一步分为青年期、壮年期和衰亡期,形成过程与短期重力流的演化过程相关。壮年期的复合水道、迁移水道和垂向加积水道为理想储层,储集性能依次减弱,水道中部储层质量一般高于两侧,近端朵叶储层质量优于分支水道。

关键词: 浊流, 碎屑流, 重力流, 水道-朵叶体系, 沉积模式, 拉什仲组, 奥陶系, 鄂尔多斯盆地

Abstract:

The fine analysis of deep-water gravity flow deposits in the Ordovician Lashenzhong Formation outcropping at the western margin of Ordos Basin, serves for revealing the evolutionary pattern and sedimentary model of deep-water gravity flow channel-lobe system, and then the reservoir distribution therein. The results show that the gravity flow depositional units in the study area include complex channels, migration channels, vertical aggradation channels with layered fill, distributary channels, as well as proximal and distal lobes, the evolution of which is closely related to the type and energy of gravity flow. At the initial stage, gravity flow is dominated by debris flows and turbidites, commonly leading to the development of complex channels. As the gravity flow gets waning in energy, turbidites become predominant, resulting in the formation of migration channels and vertical aggradation channels in succession through multi-stage erosion and sedimentation. Subsequently, distributary channels, proximal and distal lobes are generated in turn when the turbidites fade. In addition, the process of complex channel development could be divided into youthful, prime, and decline stages which are corresponding to the short-term gravity flow evolution processes. Complex channels in the prime stage, migration channels, and vertical aggradation channels are favorable reservoirs, with the storage capability declining in turn. The middle parts of channels are generally better compared with those at the flanks in terms of reservoir potential, and reservoirs of proximal lobes are superior to those of distributary channels.

Key words: turbidite, debris flow, gravity flow, channel-lobe system, depositional model, Lashenzhong Formation, Ordovician, Ordos Basin

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