摘要
位于珠一坳陷西江凹陷北部的西江主洼具有古地温梯度低、恩平组泥岩厚度大、岩浆作用多等特殊地质特征,导致其主力烃源岩潜力、原油类型和来源、油气聚集规律和成藏主控因素等复杂性.基于烃源岩有机地球化学特征和分布、原油分类、来源及分布规律、原油聚集与岩浆和断裂关系等分析,开展烃源岩分布及潜力、原油成藏规律及主控因素研究.明确了西江主洼发育文昌组下段的文4段和文昌组上段的文3段两种属性差异的中深湖相烃源岩,且改造作用强、供烃能力有差异.成藏原油可分为两种类型,其来源和空间分布存在差异,类型1原油来自于文4段烃源岩,裂陷层和拗陷层均有成藏,横向运移距离远.类型2原油来自于文3段烃源岩,裂陷层成藏,近洼聚集.成藏主控因素为烃源岩和断裂,文昌组烃源岩属性差异、体量控制了原油类型、成藏级别和运移距离.NE向断层因延走向的分段、分时活动速率变化控制烃源岩发育和展布;NWW⁃近EW向断裂控制文3段烃源岩,且为近洼处裂陷层成藏断层,为远洼处西江中低凸起拗陷层成藏断层.成藏模式可总结为:烃源控聚、断裂控层、岩浆控富.
Xijiang main sag located in the north of Xijiang sag in ZhuⅠdepression is characterized by relatively lower paleogeothermal gradient,thick mudstones in Enping Formation and more magmatism,which resulted in complexity of source rock potential,oil types and oil source,hydrocarbon accumulation and main control factors.Based on the analysis of the organic geochemical characteristics and distributions of the source rocks,oil classification,oil source and oil distribution,the relationships between oil accumulation,magmatism and faults,distribution and potential of the source rocks,the rule of oil accumulation and the main controlling factors could be identified.There are two types of middle-deep lacustrine source rocks with different attributes:the Wenchang IV Formation and the Wenchang III Formation in the Xijiang main sag,which have been strongly transformed and have different hydrocarbon supply capabilities.Two different oil groups have been recognized in Xijiang main sag,which origined from different source rocks and their spatial distributions are different.Group I oil origin from the Wenchang IV Formation source rock,distributed in the rift sequence and depression sequence reservoirs,with long lateral migration distance.Group II oil origed in from the Wenchang III Formation,only distributed in the rift sequence and accumulated near the sag.Source rocks and faults are two main controlling factors of hydrocarbon accumulation in Xijiang main sag.The difference in attribute and volume of the two type source rocks control the oils’organic geochemical characteristics,the level of hydrocarbon accumulation and the migration distance.The NE trending faults control the development and distribution of source rocks due to the change of segmentation and time-sharing activity rate.The NWW-EW trending faults control the development of the Wenchang III Formation source rock,and both control the hydrocarbon accumulation in the rift sequence near the sag and in the depression sequence in the Xijiang middle low uplift far from
作者
彭光荣
张丽丽
许新明
邱欣卫
何金海
刘昭茜
Peng Guangrong;Zhang Lili;Xu Xinming;Qiu Xinwei;He Jinhai;Liu Zhaoqian(Shenzhen Branch of CNOOC,Shenzhen 518000,China;Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China University of Geosciences,Wuhan 430074,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2023年第6期2361-2375,共15页
Earth Science
基金
中海油深圳分公司重大生产科研项目(No.SCKY⁃2020⁃SZ⁃21).
关键词
烃源岩
原油分类及来源
成藏主控因素
西江主洼
珠江口盆地
石油地质.
source rock
oil classification and oil origin
hydrocarbon accumulation main control factor
Xijiang main sag
Pearl River Mouth basin
petroleum geology.
