石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (6): 1440-1450.doi: 10.11743/ogg20210618

• 油气地质 • 上一篇    下一篇

深水局部限制型水道复合体沉积特征及其对储层性质的影响——以东非鲁武马盆地始新统为例

孙辉(), 范国章, 邵大力, 左国平, 刘少治, 王红平, 马宏霞, 许小勇, 鲁银涛, 闫春   

  1. 中国石油 杭州地质研究院, 浙江 杭州 310023
  • 收稿日期:2021-04-16 出版日期:2021-12-28 发布日期:2021-12-16
  • 作者简介:孙辉(1969-), 女, 高级工程师, 地震深水沉积及储层。E-mail: sunh_hz@petrochina.com.cn
  • 基金资助:
    中国石油天然气集团公司科学研究与技术开发项目(2019D-4309)

Depositional characteristics of locally restricted channel complex in deep water and its influence on reservoir properties: A case study of the Eocene series, Rovuma Basin

Hui Sun(), Guozhang Fan, Dali Shao, Guoping Zuo, Shaozhi Liu, Hongping Wang, Hongxia Ma, Xiaoyong Xu, Yintao Lu, Chun Yan   

  1. Hangzhou Research Institute of Geology, PetroChina, Hangzhou, Zhejiang 310023, China
  • Received:2021-04-16 Online:2021-12-28 Published:2021-12-16

摘要:

东非鲁武马盆地始新统水道砂岩储层为深水沉积环境下的重力流沉积,水道复合体具有单侧迁移、多级别侵蚀充填的特征。应用岩心观察、测井分析和三维地震属性分析等方法和技术研究水道复合体,厘清了水道复合体的沉积相与级别之间的关系,将始新统局部限制型水道复合体细分为3个亚相、3个级别和4个沉积期次,描述了4期复合水道的演化过程,分析了水道复合体的沉积单元类型、沉积期次以及距水道口距离对储集层性质的影响。鲁武马盆地始新统水道复合体由复合底层、主要限制水道充填和溢岸楔3种沉积亚相组成。水道充填沉积可以细分为水道复合体、复合水道以及水道3个级别。受底流作用影响,复合水道内部以及由早向晚演化的不同期次的复合水道间均呈现由北向南侧向迁移的特征,储集层类型以连片发育的叠置水道为主。始新统局限型水道复合体的储层性质与沉积期次、沉积单元类型和距水道口距离密切相关。砂岩储层主要发育于叠置水道和弯曲水道沉积内,叠置水道是最有利的储层类型。水道沉积越早、单砂层越厚,沉积越晚、物性越好,距水道口越近、储层厚度越大、孔隙度越低。泥质含量及渗透率随延伸距离变化关系比较复杂。研究成果不仅可以深化深水水道复合体沉积储层研究,而且适用于开发前期地质模型构建。

关键词: 复合水道, 水道复合体, 深水沉积, 储层特征, 始新统, 鲁武马盆地

Abstract:

The Eocene channel sandstone reservoirs in the Rovuma Basin, East Africa, are of deep sea gravity flow deposits. The Eocene channel complex is characterized by unilateral migration and multi-level erosion and filling. Research methods and technologies including core observation, well logging analysis, and 3D seismic attribute analysis, etc., are applied to study the channel complex. The relationship between the sedimentary facies of channel complex and its grade is clarified. The Eocene channel complex of locally restricted type can be divided into 3 subfacies, 3 grades and 4 sedimentary periods; moreover, the evolutionary process of the 4 periods is described, and the impact of sedimentary unit type, sedimentary period of the channel complex and the distance from the channel mouth on the reservoir properties is analyzed. The Eocene channel complex in the Rovuma Basin is composed of 3 sedimentary subfacies, i.e. complex substrate, main deposits of confined filling and overflow wedge. Channel filling deposition includes 3 grades of channel complex, composite channel and channel. Under the influence of bottom current, a north-to-south migration occurs within a single composite channel and between composite channels of different stages from old to young; and thereby the reservoir is mainly of the superimposing channel facies in laterally continuous distribution. On the other hand, the reservoir properties of the Eocene channel complex of local restriction type are closely associated with the sedimentary period, the type of sedimentary units and the distance from the channel mouth. Sandstone reservoirs are mainly developed in superimposing and meandering channels, and the superimposing channel facies is the most favorable to reservoir development. The earlier the channel deposition occurs, the thicker a single sandstone layer will be; however, the later the channel deposition begins, the better the physical properties of a reservoir will be, and the closer to the channel mouth, the greater the reservoir thickness and the lower the porosity will be. The variation of shale content and permeability with extension distance is complicated. In a nutshell, the research results serve for deepening the study of sedimentary reservoir of deep-water channel complex facies, as well as are of practical value to establishing geological models in the early stage of oil/gas field development.

Key words: composite channel, channel complex, deep-water deposits, reservoir characteristics, Eocene, Rovuma Basin

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