石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (6): 1255-1264.doi: 10.11743/ogg20210602

• 油气地质 • 上一篇    下一篇

渤海湾盆地油气成藏期差异性及其主控因素

蒋有录(), 苏圣民, 刘华, 赵鸿皓   

  1. 中国石油大学(华东) 地球科学与技术学院, 山东 青岛 266580
  • 收稿日期:2021-08-13 出版日期:2021-12-28 发布日期:2021-12-16
  • 作者简介:蒋有录(1959-), 男, 博士、教授、博士生导师, 油气藏形成与分布规律。E-mail: jiangyl@upc.edu.cn
  • 基金资助:
    国家科技重大专项(2016ZX05006-003)

Differences in hydrocarbon accumulation stages and main controlling factors in the Bohai Bay Basin

Youlu Jiang(), Shengmin Su, Hua Liu, Honghao Zhao   

  1. School of Geoscience, China University of Petroleum(East China), Qingdao, Shandong 266580, China
  • Received:2021-08-13 Online:2021-12-28 Published:2021-12-16

摘要:

渤海湾盆地发育数十个油气生成和运聚相对独立的凹陷,各凹陷油气大规模运聚成藏时期及期次不尽相同。以大量统计资料和烃源岩生烃演化史分析为基础,综合前人研究成果,对渤海湾盆地不同地区主力层系的油气成藏时期及期次进行了系统研究,探讨了油气成藏期差异的主控因素。研究表明:渤海湾盆地源于古近系的油气主要存在两期成藏,即古近纪末期(早期)和新近纪中期-第四纪(晚期),以晚期成藏为主;从盆地边缘凹陷向渤中凹陷,主成藏期逐渐变晚,由早期成藏为主演变为晚期成藏为主,成藏期具有早期成藏-两期成藏早期为主-两期成藏晚期为主-晚期成藏的演变特征;纵向上,从下部至中部再至浅部含油气层系,油气主成藏期总体具有早期-两期-晚期的变化特征。新生代凹陷沉降史控制了主力烃源岩生烃演化史,进而控制了不同地区油气成藏期的差异,凹陷沉降类型与凹陷主成藏期类型相对应,古近纪末剥蚀厚度与新近纪-第四纪补偿厚度控制了成藏期的主次,补偿厚度越大,晚期成藏特征越明显;主生烃期决定油气主成藏期,来自孔店组、沙河街组一段-东营组三段烃源岩的油气分别以早期、晚期成藏为主,而来自沙四上亚段、沙三段烃源岩的油气多具有两期成藏的特征。

关键词: 早期成藏, 晚期成藏, 烃源岩演化, 成藏期次, 新近系, 渤海湾盆地

Abstract:

The Bohai Bay Basin hosts dozens of sags with relatively independent petroleum systems, in which large-scale hydrocarbon migration and accumulation occurred at various geologic times and stages. A systematic investigation is conducted on the timing of hydrocarbon accumulation as well as the main controlling factors on the differences in geologic times and stages of hydrocarbon accumulation in the major reservoirs of these sags in the basin through combining a large number of statistical data and the analyses of hydrocarbon generation history of source rocks with previous studies. Results show that hydrocarbons generated by the Paleogene source rocks probably accumulated in two stages, namely the end of Paleogene (early stage) and middle Neogene-Quaternary (late stage but more important), respectively. During the whole process, the predominance of early accumulation has been gradually taken over by the late accumulation from the basin edge sag inward to the Bozhong sag, and the accumulation stages feature in changing from single stage of early accumulation to two stages with early accumulation predominance, to two stages with late accumulation predominance, and to single stage of late accumulation. Vertically from deep to middle and further to shallow reservoirs, hydrocarbon accumulation stages change from single stage of early accumulation to two stages and further to single stage of late accumulation. The subsidence patterns of the sags during the Cenozoic are suggested to be the major control over the thermal evolution of source rocks, which in turn controls the differences of hydrocarbon accumulation stages, resulting in a good correspondence between the subsidence patterns and the dominant accumulation stages. The denuded thickness at the end of Paleogene and the sedimentary thickness of Neogene-Quaternary are believed to be the determining factor on which accumulation stage being predominant. Observation shows that the greater the compensation thickness, the more obvious the characteristics of late accumulation stage. The main hydrocarbon generation periods determine the main hydrocarbon accumulation stages. Hydrocarbons sourced from the Kongdian Formation source rocks is likely to accumulate mainly in the early stage, while that from the source rocks in the first member of Shahejie Formation to the third member of the Dongying Formation is more likely to be related to the late accumulation. Hydrocarbons from source rocks in the upper fourth and third members of Shahejie Formation shows characteristics of two stage accumulation.

Key words: early stage accumulation, late stage accumulation, evolution of source rock, hydrocarbon accumulation stage, Neogene, Bohai Bay Basin

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