莺歌海盆地中央底辟带乐东区莺歌海组超压成因及相对贡献定量化评价  

Overpressure Mechanisms and Quantitative Evaluation of Relative Contribution for Yinggehai Formation in Ledong Area of Central Diapir Zone,Yinggehai Basin

作　　者：张旭友 范彩伟 郭小文[1] 吴云鹏 刘爱群 高英博 黄亚浩 Zhang Xuyou;Fan Caiwei;Guo Xiaowen;Wu Yunpeng;Liu Aiqun;Gao Yingbo;Huang Yahao(Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China University of Geosciences,Wuhan 430074,China;Zhanjiang Branch of CNOOC China Limited,Zhanjiang 524057,China;Hainan Branch of CNOOC China Limited,Haikou 570312,China;College of Resources and Environment,Yangtze University,Wuhan 430100,China)

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [2]中海石油(中国)有限公司湛江分公司,广东湛江524057 [3]中海石油(中国)有限公司海南分公司,海南海口570312 [4]长江大学资源与环境学院,湖北武汉430100

出　　处：《地球科学》2024年第10期3547-3558,共12页Earth Science

基　　金：国家自然科学基金(Nos.U20B6001,41872139)。

摘　　要：莺歌海盆地中央底辟带莺歌海组广泛发育超压,超压泥岩表现为异常高声波时差、低电阻率和低密度特征.在对莺歌海盆地中央底辟带莺歌海组超压成因机制综合分析基础之上,定量化评价不同成因类型超压贡献率.结果表明:莺歌海盆地中央底辟带莺歌海组泥岩超压成因机制包括欠压实、有机质生烃和超压传递作用,粘土矿物转化对超压贡献不明显.超压贡献率定量化评价结果揭示了底辟区流体压力传递和生烃作用对泥岩超压发育具有重要贡献.莺歌盆地中央底辟带乐东区莺歌海组泥岩欠压实超压贡献率为38%~100%,随着埋藏深度的增加,欠压实超压贡献率逐渐减小.莺一段地层埋深浅,生烃能力弱,以欠压实成因机制超压为主;莺二段泥岩生烃能力显著增强,生烃增压贡献率最大可达51.53%.底辟区微裂隙和断裂发育,使深部流体运移至浅层而发生压力传递,压力传递作用对莺歌海组超压贡献率最大超过50%.Overpressure is widely developed of Yinggehai Formation in Ledong area of the central diapir zone.The overpressure mudstone is characterized by abnormally higher acoustic travel time,lower resistivity and density than that of the normal pressured mudstones.In this paper,the contribution rate of overpressure caused by different mechanisms is quantitatively evaluated based on the comprehensive analysis of the overpressure mechanisms of Yinggehai Formation in the central diapir zone of Yinggehai basin.The results indicate that the main causes of overpressure in Yinggehai Formation in Ledong area of the central diapir zone include undercompaction,hydrocarbon generation of organic matter and overpressure transfer.The contribution of clay mineral transformation to the overpressure is not obvious.The quantitative study of overpressure contribution rate reveals the contribution of fluid pressure transfer and hydrocarbon generation to mudstone overpressure in the diapir area of Yinggehai Basin.The contribution rate of overpressure caused by undercompaction in the Ledong Area of the Central Diapir Zone of Yinggehai Basin ranges from 38%to 100%.As the burial depth increases,the contribution rate of undercompaction-induced overpressure gradually decreases.The main overpressure mechanisms in the first member of Yinggehai Formation is undercompaction with the shallow buried depth and weak hydrocarbon generation capacity.While the hydrocarbon generation capacity of mudstone in the second member of Yinggehai Formation is significantly enhanced,the contribution caused by hydrocarbon generation is up to 51.53%.Microfractures and faults are developed in the diapir area,which make the deep fluid migrate to the shallow layer and produces pressure transfer.The maximum contribution rate of pressure transfer is more than 50%in Yinggehai Formation.

关 键 词：欠压实 底辟区 超压成因 超压贡献率 莺歌海盆地 石油地质学 

分 类 号：P624[天文地球—地质矿产勘探]