西北非毛塞几比盆地下白垩统尼欧可木阶海相烃源岩发育特征及控制因素  

Characteristics and controlling factor of the Lower Cretaceous Neocomian marine source rocks in the MSGBC Basin,NW Africa

作　　者：詹鑫 Zhan Xin(CNOOC International Limited,Beijing 100028)

机构地区：[1]中国海洋石油国际有限公司,北京100028

出　　处：《地质科学》2025年第2期497-510,共14页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国海洋石油有限公司“十四五”重大科技项目(编号:KJGG2022-0901)资助。

摘　　要：长期以来前人对毛塞几比盆地下白垩统尼欧可木阶烃源岩的研究极少且关注度不够,对尼欧可木阶烃源岩品质与生烃潜力认识不清,尤其是对尼欧可木阶优质烃源岩发育控制因素缺乏系统的研究。探讨其品质与时空分布特征以及优质烃源岩发育主控因素,可为盆地及其周缘油气勘探提供思路与依据。本文运用大洋钻探井等资料,综合分析研究毛塞几比盆地尼欧可木阶烃源岩岩相、沉积相、有机相、古地理、古生态,详尽阐明了该区域尼欧可木阶烃源岩品质特征与时空分布特征。研究结果表明,尼欧可木阶中-上部所对应的深水陆棚厌氧腐泥—腐殖有机相烃源岩品质最优。DSDP-367井瓦兰今阶TOC、S_(2)、HI指标与δ^(13)C_(carb)明显的同步耦合关系,表明瓦兰今期Weissert大洋缺氧事件是尼欧可木阶优质烃源岩发育的直接控制因素。在毛塞几比盆地及其周缘全面系统地开展尼欧可木阶烃源岩品质与生烃潜力评价,首次阐明了优质烃源岩的时空分布特征并指明了优质烃源岩的关键控制因素,为明确盆地油气勘探方向提供依据,同时也为中大西洋两岸被动大陆边缘盆地少井或无井条件下海相烃源岩的研究提供了新思路。Previous studies on the Lower Cretaceous Neocomian source rocks in the MSGBC Basin have been restricted and largely ignored for a long time.Quality and hydrocarbon generation potential of Neocomian source rocks have not been clearly understood.Especially,controlling factors for the development of high‑quality Neocomian source rocks have not been systematically studied.This paper aims to determine the quality characteristics and spatial and temporal distribution characteristics of Neocomian source rocks,as well as the key controlling factors,guiding for hydrocarbon exploration in the MSGBC Basin.Lithofacies,sedimentary facies,organofacies,paleogeography,and paleoecology of Neocomian source rocks in the MSGBC Basin have been comprehensively analyzed,using data from DSDP wells,to elaborate the quality characteristics and spatial and temporal distribution characteristics of Neocomian source rocks in this area.The result shows that the most excellent source rocks were developed in pelagic anoxic sapropelic‑humic organofacies.Significantly,the concurrent changes of TOC,S_(2),HI,andδ^(13)C_(carb)of Valanginian rocks in DSDP‑367 well indicate that thedevelopment of high‑quality Neocomian source rocks was directly controlled by the Weissert Oceanic AnoxicEvent during Valanginian.A systematical evaluation was conducted on quality and hydrocarbon generationpotential of Neocomian source rocks in the MSGBC Basin in this study.The study elaborates,for the first time,thespatial and temporal distribution characteristics of excellent hydrocarbon source rocks and reveals their keycontrolling factors,providing guidance for oil and gas exploration in the basin,as well as insight into themethodology of marine source rock study in the passive continental margin basins of the mid‑Atlantic Ocean,withlimited data from only a few or no wells.

关 键 词：大洋钻探井 岩相 沉积相 有机相 古生态 古地理 Weissert大洋缺氧事件 

分 类 号：TE122.1[石油与天然气工程—油气勘探]