低钻揭洼陷有利烃源岩空间展布地质与地球物理综合识别方法——以珠江口盆地珠一坳陷恩平17洼为例

Discussion on integrated geological and geophysical identification method for spatial distribution of favorable source rocks in depression with lack of drilling data: a case study of Enping 17 Sag, Zhu Ⅰ Depression, Pearl River Mouth Basin

彭光荣 龙祖烈 史玉玲 石创 杨兴业 刘灵 马晓楠

PENG Guangrong LONG Zulie SHI Yuling SHI Chuang YANG Xingye LIU Ling MA Xiaonan

中海石油(中国)有限公司 深圳分公司，广东 深圳 518054 中海石油 深海开发有限公司，广东 深圳 518054

Shenzhen Branch of CNOOC (China) Co., Ltd., Shenzhen, Guangdong 518054, China CNOOC Deepwater Development Limited, Shenzhen, Guangdong 518054, China

为解决珠江口盆地珠一坳陷低钻揭洼陷有利烃源岩展布的综合识别问题，以珠江口盆地珠一坳陷恩平17洼为例，在对烃源岩发育地质背景、沉积特征及岩石物理特征分析的基础上，以不同沉积环境烃源岩的岩石物理特征约束指导地震反演；根据钻揭烃源岩岩相与反演阻抗体关系统计，通过地质建模进行有利烃源岩空间展布的半定量预测；结合原油的地化成因类型及来源认识分析预测方法及结果的合理性，探讨低钻揭洼陷有利烃源岩空间展布的地质与地球物理综合识别方法。古近系文昌组烃源岩沉积环境越好，有利烃源岩段的阻抗值越低，与差烃源岩或非烃源岩段之间的阻抗差异越大。从预测结果看，文三段、文四段及文五段是恩平17洼的主力烃源岩段，这一认识得到了原油生物标志化合物研究的支持。在石油地质背景条件基本明确的珠江口盆地各小洼陷，建立烃源岩岩相与反演阻抗值之间的定量、半定量关系，有助于快速明确主力烃源岩发育层段及规模，这一方法具有较好的推广应用前景。

Due to the lack of drilling data in the Zhu 1 Depression of the Pear River Mouth Basin, the Enping 17 Sag is taken as an example in this paper to solve the problem of comprehensive identification of underground distribution of high-quality source rocks. Based on the analysis of the geological background, sedimentary characteristics and petrophysical characteristics of source rocks, seismic inversion is guided by the constraints of the petrophysical characteristics of the source rocks in different sedimentary environments. According to the statistics of the relationship between the lithofacies of drilled source rocks and the inversion resistance, a semi-quantitative prediction of the spatial distribution of favorable source rocks is made by geological modeling, and the rationality of prediction method and results is analyzed in combination with the recognition of the geochemical origin type and source of crude oil, to discuss the geological and geophysical identification method of the underground distribution of high-quality source rocks with lack of drilling data. The more reductive the depositional environment of source rocks in the Paleogene Wenchang Formation, the lower the impedance value of high-quality source rocks, and the greater the impedance difference between poor source rocks or non-source rocks. The third, fourth and fifth members of Wenchang Formation are the main source rocks of the Enping 17 Sag, which can be supported by the study of crude oil biomarkers. In the small sags of the Pearl River Mouth Basin with basically clear petroleum geological background conditions, establishing the quantitative and semi-quantitative relationship between the lithofacies of source rocks and the inversion impedance value is helpful to quickly clarify the development interval and scale of main source rocks. This method has a good prospect of popularization and application.

中海石油深海开发有限公司项目 KJZH-2021-0003-00;中国海洋石油集团有限公司重大科技项目 KJGG2022-0403

https://doi.org/10.11781/sysydz2022061116