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现代地质 ›› 2024, Vol. 38 ›› Issue (05): 1235-1247.DOI: 10.19657/j.geoscience.1000-8527.2024.099

• 沉积盆地油气勘探与关键技术 • 上一篇    下一篇

琼东南盆地二号断裂带断层封闭性评价

田澜希1,2(), 张冠杰1,2, 雷新3   

  1. 1.中国地质大学(武汉)资源学院,湖北 武汉 430074
    2.中国地质大学(武汉)构造与油气资源教育部重点实验室,湖北 武汉 430074
    3.中海石油(中国)有限公司湛江分公司,广东 湛江 524057
  • 出版日期:2024-10-10 发布日期:2024-11-13
  • 作者简介:田澜希,女,硕士研究生,2000年出生,主要从事构造地质学和含油气盆地分析方向研究。Email: LXTIAN@cug.edu.cn
  • 基金资助:
    中海油南海西部油田上产2000万方关键技术研究项目(CNOOC-KJ135ZDXM38ZJ);中国海洋石油有限公司“十四五”重大科技专项“中国近海新区新领域勘探技术”(KJGG2022-0301)

Evaluation of Fault Sealing in the No.2 Fault Zone of the Qiongdongnan Basin

TIAN Lanxi1,2(), ZHANG Guanjie1,2, LEI Xin3   

  1. 1. China University of Geosciences, Wuhan, Hubei 430074, China
    2. Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan, Hubei 430074, China
    3. Zhanjiang Branch, China National Offshore Oil Corporation Zhanjiang, Guangdong 524057, China
  • Published:2024-10-10 Online:2024-11-13

摘要:

二号断裂是琼东南盆地重要的“穿层沟源”基底断裂,沟通了油源和圈闭,起到输导和分配油气的作用。为明确二号断裂不同区段断层封闭差异性,对该区后续的勘探开发提供可靠的理论依据、完善断层封闭性评价方法,本文在地震资料精细解释的基础上,结合断层活动性计算,将琼东南盆地二号断裂带在平面上分为东、中、西三段,通过计算断面正应力(F)、泥岩涂抹比率(SGR)以及泥质充填指数(Rm),利用模糊数学评价方法对二号断裂带不同区段开展了断层封闭性定量评价,并利用流体包裹体测试数据、薄片观察以及扫描电镜分析实验,通过成岩胶结作用和原油稠化作用定性评价不同区段断层相关裂缝带封闭性的差异。结果表明,二号断裂带断层封闭性具有区域性特征,西段封闭性较好,可作为油气运移的有效遮挡,东段次之,断层封闭性中段要求最高;西段裂缝带为矿物胶结封闭,而中段和东段为原油稠化充填,形成封闭时间相对较晚;总体而言二号断裂带的封闭是在压实、充填作用的基础上,多期热液矿物结晶胶结和原油稠化的结果。

关键词: 模糊数学评价, 定性评价, 断层封闭性, 二号断裂带, 琼东南盆地

Abstract:

The No.2 Fault is a key basement fault in the Qiongdongnan Basin, connecting the oil source and trap, and playing a crucial role in transport and distribution of oil and gas. This study aims to clarify the difference in fault sealing across various sections of the No.2 Fault, providing a reliable theoretical basis for subsequent exploration in this area and improving fault sealing evaluation methods through detailed seismic data interpretation. Based on fault activity calculations, the No.2 Fault Zone in the Qiongdongnan Basin can be divided into three sections: eastern, central, and western. Based on this, we quantitatively evaluated the fault sealing ability of different sections of the No.2 Fault Zone using the fuzzy mathematical evaluation method, by calcula-ting normal stress for section (F), mudstone cutting ratio (SGR), and mud filling index (Rm). Additionally, we qualitatively evaluated the sealing properties of fracture-related zones in different sections using fluid inclusions, thin section observation, and scanning electron microscopy, focusing on diagenetic cementation and oil thickening. The results indicate that the fault sealing characteristics of the No.2 Fault Zone exhibit regional variability, with the western section demonstrating superior fracture sealing and serving as an effective barrier for oil and gas migration, followed by the eastern section. The central section has the greatest need for enhanced fracture sealing. The western fracture zone is sealed by mineral cement, whereas the central and eastern sections are filled with thickened crude oil, with sealing occurring relatively later. Overall, the sealing of the No.2 Fault Zone is the result of multi-stage hydrothermal mineral crystallization and oil thickening, occurring on top of compaction and filling processes.

Key words: fuzzy mathematic evaluation, qualitative evaluation, fault closure, No.2 Fault Zone, Qiongdongnan Basin

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