石油学报 ›› 2026, Vol. 47 ›› Issue (2): 375-393.DOI: 10.7623/syxb202602006

• 地质勘探 • 上一篇    

西湖凹陷平湖斜坡带平北区原油地球化学特征及母质溯源

张铜磊1, 蒋一鸣1, 李宁1, 覃军1, 史恭乐2, 蔡坤1, 徐东浩1, 徐波3, 张亚男3   

  1. 1. 中海石油(中国)有限公司上海分公司 上海 200335;
    2. 中国科学院南京地质古生物研究所 江苏南京 210008;
    3. 中海油能源发展股份有限公司工程技术分公司中海油实验中心上海实验中心 上海 200941
  • 收稿日期:2025-06-26 修回日期:2025-10-09 发布日期:2026-03-13
  • 通讯作者: 张铜磊,男,1983年3月生,2012年获中国石油大学(北京)博士学位,现为中海石油(中国)有限公司上海分公司高级工程师,主要从事烃源岩及油气地球化学方向研究。
  • 作者简介:张铜磊,男,1983年3月生,2012年获中国石油大学(北京)博士学位,现为中海石油(中国)有限公司上海分公司高级工程师,主要从事烃源岩及油气地球化学方向研究。
  • 基金资助:
    中海石油(中国)有限公司科技重大专项课题1“东海西湖凹陷大中型气田勘探方向及关键技术研究”(KJZX-2023-0101)资助。

Geochemical characteristics and origin of crude oil in Pingbei area of Pinghu slope belt,Xihu sag

Zhang Tonglei1, Jiang Yiming1, Li Ning1, Qin Jun1, Shi Gongle2, Cai Kun1, Xu Donghao1, Xu Bo3, Zhang Ya'nan3   

  1. 1. Shanghai Branch, CNOOC China Limited, Shanghai 200335, China;
    2. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Jiangsu Nanjing 210008, China;
    3. Shanghai Branch of CNOOC Central Laboratory, Oilfield Technology Engineering Company, CNOOC Energy Technology & Services Limited, Shanghai 200941, China
  • Received:2025-06-26 Revised:2025-10-09 Published:2026-03-13

摘要: 西湖凹陷平湖斜坡带平北区具有较为丰富的原油资源。已有研究证实该原油主要来自于高等植物,但原油中典型生物标志化合物的生源意义目前仍存在明显分歧且原油的成因分类研究较为薄弱,从而限制了平北区原油分布规律的研究以及进一步勘探。基于西湖凹陷平湖斜坡带平北区原油的地球化学特征,结合原油中典型生物标志化合物前体在生物群落中的分布情况以及研究区的古植物化石信息,明确了关键生物标志化合物的生源意义,完成了参数优选并开展了原油成因类型划分。基于精细油-源对比,结合平湖组烃源岩沉积期的古地貌和沉积环境特征,指明了原油的有利勘探方向。研究结果表明:二萜化合物与nC27比值可以有效表征裸子植物的输入强度,而1,2,7-三甲基萘与1,3,7-三甲基萘比值则可以有效表征被子植物的输入强度,利用这2个参数可将研究区的原油划分为Ⅰ型(中强度裸子植物输入、弱强度被子植物输入)、Ⅱ型(中强度裸子植物输入、高强度被子植物输入)以及Ⅲ型(高强度裸子植物输入)3种类型;原油的二萜化合物中丰富的异海松烷、4β(H)-19-降异海松烷和16β(H)-扁枝烷主要来源于裸子植物柏科杉亚科,1,2,7-三甲基萘和奥利烷主要来源于被子植物中的木本双子叶植物;研究区原油主要来自于平湖组中—下段烃源岩,且近源成藏特征显著;受潮流影响弱的潮上带、潮间带和障壁岛等地貌高势区以及大型潟湖周边有利于高大植物生长,是形成优质煤系烃源岩以及原油勘探的有利区。研究成果对分析西湖凹陷平湖斜坡带平北区原油母质来源与开展成因分类精细研究,综合应用分子地球化学与植物化石信息以及提出原油有利勘探方向等具有一定的指导意义。

关键词: 地球化学特征, 原油成因类型, 生物标志化合物, 裸子植物, 被子植物, 勘探方向, 平湖斜坡带, 西湖凹陷

Abstract: The Pingbei area of the Pinghu slope belt in Xihu sag is rich in crude oil resources, and the existing studies have confirmed that the oil primarily originates from higher plants. However, there is still significant debate regarding the source implications of the typical biomarker compounds in crude oil, and also less research on the genetic classification of the crude oil. These issues have impeded the study of crude oil distribution patterns and further exploration in the region. Based on the geochemical characteristics of crude oil in the Pingbei area, combined with the distribution of precursors of typical biomarkers in biological communities and the paleofloral fossil records of the study area, the paper has clarified the source implications of key biomarker compounds, optimized the classification parameters, and developed a genetic classification of the crude oil. Furthermore, through integrating the detailed oil-source correlation with the paleogeomorphic and sedimentary environmental characteristics of the Pinghu Formation source rocks, favorable exploration targets for crude oil have been identified. The findings indicate as follows. (1) The ratio of diterpenoids to nC27 effectively quantifies the gymnosperm input intensity, while the ratio of 1, 2, 7-trimethylnaphthalene to 1, 3, 7-trimethylnaphthalene serves as a reliable indicator of angiosperms input intensity. Using these two parameters, the crude oil in the study area is classified into three genetic types, i.e., Type Ⅰ (medium gymnosperm input, weak angiosperm input), Type Ⅱ (medium gymnosperm input, strong angiosperm input), and Type Ⅲ (strong gymnosperm input). (2) The abundant diterpenoids in the crude oil, including isopimarane, 4β(H)-19-norisopimarane, and 16β(H)-phyllocladane, are mainly sourced from the Cupressoideae, a subfamily of gymnosperms. Additionally, 1, 2, 7-trimethylnaphthalene and oleanane are predominantly derived from woody dicotyledons of Angiosperms. (3) The crude oil in the study area is mainly sourced from source rocks in the middle to lower members of Pinghu Formation, dominantly featuring near-source accumulation. (4) Paleogeomorphologically elevated areas with minimal tidal influence, such as supratidal zones, intertidal zones, barrier islands, and the periphery of large lagoons, are conducive to the growth of tall plants. These regions are favorable for the formation of high-quality coal-bearing source rocks and represent promising areas for oil exploration. The research provide valuable guidance for analyzing the parent material sources of crude oil in the Pingbei area, conducting in-depth studies of oil genetic classification methodologies, comprehensively applying molecular geochemistry and paleofloral fossil data, and proposing favorable exploration areas for crude oil in Xihu sag.

Key words: geochemical characteristics, genetic types of crude oil, biomarker compounds, gymnosperms, angiosperms, exploration direction, Pinghu slope belt, Xihu sag

中图分类号: