西湖凹陷始新统宝石组优质烃源岩初探  

Preliminary study on high-quality source rocks in the Baoshi Formation of the Eocene in Xihu Sag

作　　者：张年念 万延周 何新建 ZHANG Niannian;WAN Yanzhou;HE Xinjian(Shanghai Branch of CNOOC(China)Limited,Shanghai 200030,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200030

出　　处：《复杂油气藏》2024年第2期152-156,161,共6页Complex Hydrocarbon Reservoirs

基　　金：中海石油(中国)有限公司“七年行动计划”重大科技专项(CNOOC-KJ 135 ZDXM 39)。

摘　　要：东海盆地西湖凹陷的勘探开发层系主要集中在始新统平湖组和渐新统花港组,随着油气勘探形势的日趋严峻,勘探方向急需加深并向下始新统宝石组拓展。从宝石组沉积环境和古生物特征入手,利用现有资料,对宝石组烃源岩有机质丰度、类型和成熟度、有机质碳同位素等开展综合评价,探索研究区宝石组优质烃源岩的分布和勘探潜力。研究指示YZ-1井区宝石组为局限海沉积环境;宝石组烃源岩有机质丰度可达中等;有机质显微组分以镜质组+惰质组为主,主要为腐殖型(Ⅲ型)。族组分的碳同位素分析显示宝石组烃源岩在母质类型方面呈现混源特征;现有宝石组上段烃源岩样品有机质成熟较低,普遍低于0.8%,推测其下段成熟度较高。综合分析认为,西湖凹陷中北部的三个深洼区可能存在宝石组优质烃源岩,可作为下一步油气勘探的思路。The exploration and development of the Xihu Sag in the East China Sea Basin are mainly concentrated in the Eocene Pinghu Formation and the Oligocene Huagang Formation.With the increasingly severe situation of hydrocarbon exploration,it is urgent to deepen and expand the exploration direction to the Lower Eocene Baoshi Formation.Based on the sedimentary environment and paleontological characteristics of the Baoshi Formation and utilizing the existing data,a comprehensive evaluation of the abundance,type,maturity,and carbon isotopes of the organic matter in the hydrocarbon source rocks of the Baoshi Formation is carried out to explore the distribution and exploration potentials of the high-quality hydrocarbon source rocks of the Baoshi Formation in the study area.The study indicates that the Baoshi Formation in the YZ-1 well area is a restricted marine sedimentary environment.The organic matter abundance of the hydrocarbon source rocks in the Baoshi Formation is medium.The maceral of organic matter is mainly vitrinite and inertinite,which is mainly humic type(type III).Carbon isotope analysis of the group components shows that mixed sources in terms of parent material type characterize the hydrocarbon source rocks of the Baoshi Formation.The organic matter maturity of the existing source rock samples in the upper part of the Baoshi Formation is relatively low,generally lower than 0.8%,and it is presumed that the maturity of the lower part is higher.Comprehensive analysis shows that there may be high-quality hydrocarbon source rocks of the Baoshi Formation in the three deep depression areas in the north-central part of the Xihu Sag,which can be used as an idea for the next step of oil and gas exploration.

关 键 词：沉积环境 有机质丰度 混源 烃源岩特征 宝石组 

分 类 号：TE121.3[石油与天然气工程—油气勘探]