中国石油勘探 ›› 2020, Vol. 25 ›› Issue (5): 23-31.DOI: 10.3969/j.issn.1672-7703.2020.05.004

• 勘探案例 • 上一篇    下一篇

涠西南凹陷流一段高位体系域湖底扇沉积特征及勘探意义

胡德胜1,范彩伟1,朱红涛2,刘 圣2,宫立园 1   

  1. 1 中海石油(中国)有限公司湛江分公司;2 中国地质大学(武汉)
  • 出版日期:2020-09-14 发布日期:2020-09-12
  • 基金资助:
    国家科技重大专项“南海西部海域低渗油藏勘探开发关键技术”( 2016ZX05024-006)。

Sedimentary characteristics and exploration significance of sub-lacustrine fan of highstand system tract in the first member of Liushagang Formation in the Weixinan sag

Hu Desheng1, Fan Caiwei1, Zhu Hongtao2, Liu Sheng1, Gong Liyuan1   

  1. 1 Zhanjiang Branch of CNOOC Ltd.; 2 China University of Geoscience (Wuhan)
  • Online:2020-09-14 Published:2020-09-12
  • Supported by:
     

摘要: 涠西南凹陷 B洼流一段高位体系域湖底扇是岩性油气藏勘探的重要领域,但是在湖底扇的特征、分类、 展布、成因机制和发育模式等方面认识不清,制约了勘探进程和成效。基于钻井、岩心、测井、分析化验及三维地震 等资料对B洼流一段高位体系域湖底扇进行了系统刻画,研究结果表明:①B洼流一段高位体系域湖底扇可分为2 大类4小类,分别为高位早期的块体流型湖底扇(又可分为下切水道中心型、下切水道侧翼型)和高位晚期碎屑流型 湖底扇(又可分为无水道化富砂型和无水道化富泥型)。②各类湖底扇在岩性、测井和地震上都表现为不同的特征。 ③湖平面变化、物源体系、搬运路径等耦合控制了两种发育模式,分别为西部轴向物源曲流河三角洲—沉积挠曲坡折— 富泥型湖底扇沉积模式和北西物源扇三角洲—断裂转换坡折—富砂型湖底扇沉积模式。④由北西向扇三角洲供源的下 切水道中心型块体流和无水道化富砂型碎屑流湖底扇砂体埋深浅、物性好,与流一段湖相泥岩形成自生、自储、自盖 的成藏组合,具有较大勘探价值。

 

关键词: 涠西南凹陷, 湖底扇, 平面展布, 沉积模式

Abstract: Sub-lacustrine fans in the highstand system tract in the first member of the Liushagang Formation (the Liu-1 member) in B sub sag of the Weixinan sag are an important field for lithologic reservoir exploration. However, the characteristics, classification, distribution, genetic mechanisms, and development patterns of sub-lacustrine fans are not well understood, which constrains the exploration process and achievements. In this study, drilling, core, well logging, laboratory analysis and 3D seismic data are used to systematically describe the sub-lacustrine fans in the highstand system tract in the Liu-1 member in B sub-sag. The results show that: (1) The sub-lacustrine fans in the highstand system tract in the Liu-1 member in B sub-sag can be divided into two major types and four sub-types: mass-flow sub-lacustrine fans in the early highstand stage (which can be further divided into incised-channel center type and incised-channel flank type), and debris-flow sub-lacustrine fans in the late highstand stage (which can also be further divided into non-channelized sand-rich type and non-channelized mud-rich type). (2) Different types of sub-lacustrine fans all present different characteristics in lithology and in well logging and seismic data. (3) There are two development models, which are jointly controlled by lake level changes, sediments source systems, and transport routes. The first depositional model is meandering river delta - sedimentary flexure slope break - mud-rich sub-lacustrine fan with the sediments source co-axial with the sub-sag to the west. The second depositional model is fan delta - fault transition slope break - sand-rich sub-lacustrine fan with the sediments source to the northwest of the sub-sag. (4) Sub-lacustrine fan sand bodies of the incised- channel center mass-flow type and the non-channelized sand-rich debris-flow type, supplied by fan delta sediments from the northwest source, have shallow burial depths and good reservoir properties. The sand bodies form a self-generating, self-storage, and self-sealing hydrocarbon accumulation assemblage with the lacustrine mudstones in the Liu-1 member—an assemblage which has great exploration prospect.

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