石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (5): 1203-1217.doi: 10.11743/ogg20230510

• 油气地质 • 上一篇    下一篇

渤海湾盆地东营凹陷民丰洼陷陡坡带深层-超深层碎屑岩优质储层控制因素

刘佳庚1,2(), 王艳忠1,2(), 操应长1,2, 王淑萍3, 李雪哲1,2, 王铸坤1,2   

  1. 1.深层油气全国重点实验室,中国石油大学(华东),山东 青岛 266580
    2.中国石油大学(华东) 地球科学与技术学院,山东 青岛 266580
    3.中国石油大学(华东) 石油工业训练中心,山东 青岛 266580
  • 收稿日期:2023-06-09 修回日期:2023-08-07 出版日期:2023-10-19 发布日期:2023-10-19
  • 通讯作者: 王艳忠 E-mail:1160898730@qq.com;wyzh@upc.edu.cn
  • 第一作者简介:刘佳庚(1995—),男,博士研究生,沉积学、储层地质学。E?mail: 1160898730@qq.com
  • 基金项目:
    国家自然科学基金项目(42272165)

Factors controlling the development of deep and ultra-deep coarse-grained siliciclastic reservoirs with high quality in the steep slope zone of the Minfeng sub-sag, Dongying Sag, Bohai Bay Basin

Jiageng LIU1,2(), Yanzhong WANG1,2(), Yingchang CAO1,2, Shuping WANG3, Xuezhe LI1,2, Zhukun WANG1,2   

  1. 1.Key Laboratory of Deep Oil and Gas,China University of Petroleum (East China),Qingdao,Shandong 266580,China
    2.School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266580,China
    3.Petroleum Industry Training Center,China University of Petroleum (East China),Qingdao,Shandong 266580,China
  • Received:2023-06-09 Revised:2023-08-07 Online:2023-10-19 Published:2023-10-19
  • Contact: Yanzhong WANG E-mail:1160898730@qq.com;wyzh@upc.edu.cn

摘要:

含油气盆地深层-超深层是全球油气勘探的新领域之一,而对深层-超深层优质储层发育主控因素认识不清制约了其油气勘探。以渤海湾盆地民丰洼陷陡坡带古近系沙河街组四段下亚段(沙四下亚段)近岸水下扇砂砾岩储层为研究对象,综合利用铸体薄片观察、扫描电镜观察、阴极发光薄片鉴定、流体包裹体测温及古压力恢复等方法,结合埋藏史-热史分析,对储层基本特征、油气充注史、压力演化史和优质储层控制因素进行综合研究。结果表明:民丰洼陷陡坡带沙四下亚段砂砾岩储层岩石类型多样,以岩屑质长石砂岩和长石质岩屑砂岩为主;压实作用中等-强,胶结作用以铁白云石胶结为主,其次为石英自生加大;溶解作用整体较弱,主要为长石溶蚀;储集空间以原生孔隙为主,发育少量的长石溶孔。储层中发生过2期石油充注和1期天然气充注:早期石油充注为成熟油充注,发生时间为37.2~25.8 Ma;晚期石油充注为高熟油充注,发生时间为12.0 Ma至今;天然气充注时间为3.6 Ma至今。储层中发育2个增压旋回,第一个增压旋回为45.0~24.6 Ma,第二个增压旋回为24.6 Ma至今,分别对应于2期油气充注期。有利的岩相是民丰洼陷陡坡带沙四下亚段原生孔隙主导型优质储层发育的基础,超压油气充注抑制压实和胶结作用是优质储层发育的关键,深层封闭体系中长石和碳酸盐矿物溶解作用弱、增孔量少;3 750 m以深的储层孔隙度随埋深加大而减少的速率明显下降,深层原生孔隙主导型优质储层的发育大大拓展了勘探的深度下限。

关键词: 沉积作用, 成岩作用, 超压油气充注, 储层特征, 沙四下亚段, 民丰洼陷, 渤海湾盆地

Abstract:

Deep and ultra-deep layers within petroliferous basins have emerged as new targets in global oil and gas exploration. However, the major factors influencing the development of high-quality reservoirs within these layers remain poorly understood, posing challenges for effective exploration. This study focuses on the coarse-grained siliciclastic reservoirs in the nearshore subaqueous fan in the lower submember of the 4th member of the Shahejie Formation in the steep slope zone of the Minfeng sub-sag, Dongying Sag. By combining methodologies including casting thin section observation, scanning electron microscopy (SEM), cathodoluminescence microscopy-based identification of minerals in thin sections, fluid inclusion thermometry, and paleopressure reconstruction, as well as the analytical results of the burial and thermal history, we comprehensively examine the reservoirs’essential characteristics, hydrocarbon charging history, pressure evolution, and factors controlling the development of high-quality reservoirs. The findings include: (1) The coarse-grained siliciclastic reservoirs in the study area are predominantly lithic arkoses and feldspathic litharenites. They exhibit medium to strong compaction and are dominated by ferrodolomite cementation, followed by quartz overgrowth. They show overall weak dissolution dominated by feldspar dissolution. The reservoir spaces comprise mostly primary pores, along with some others developed from feldspar dissolution. (2) Two oil charging stages and one natural gas charging stage were identified: an early mature-oil charging between 37.2~25.8 Ma and a later highly-mature-oil charging from 12 Ma onwards. The natural gas charging has lasted till now since 3.6 Ma. (3) The reservoirs have experienced two distinct pore pressure-increasing cycles: 45~24.6 Ma and from 24.6 Ma to present, corresponding to the two hydrocarbon charging stages. (4) Favorable lithofacies lay the foundation for the development of high-quality reservoirs dominated by primary pores in the study area. The inhibitive effects of overpressure hydrocarbon charging on compaction and cementation are crucial to the development of high-quality reservoirs. The weak dissolution of feldspar and carbonate minerals in the deep closed system leads to a low increment in porosity. However, the reduction rate of the reservoir porosity with depth declines significantly at burial depths beyond 3 750 m, and the development of deep high-quality reservoirs dominated by primary pores expands the lower limit of depth for exploration.

Key words: sedimentation, diagenesis, overpressure hydrocarbon charging, reservoir characteristics, lower submember of the 4th member of the Shahejie Formation, Minfeng subsag, Bohai Bay Basin

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