酒西盆地红柳峡地区下白垩统烃源岩孢粉相与沉积古环境特征  

Palynofacies and sedimentary paleoenvironment of Lower Cretaceous source rocks in Hongliuxia area,Jiuxi Basin

作　　者：马博 吉利明 张明震 金培红 苑伯超 龙礼文[5] MABo;JI Liming;ZHANG Mingzhen;JIN Peihong;YUAN Bochao;LONG Liwen(Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;State Key Laboratory of Paleobiology and Stratigraphy(Nanjing Institute of Geology and Paleontology,Chinese Academy of Sciences),Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute of Exploration and Development,PetroChina Yumen Oilfield Company,Jiuquan 735019,Gansu,China;PetroChina Research Institute of Petroleum Exploration and Development-Northwest,Lanzhou 730020,China)

机构地区：[1]中国科学院西北生态环境资源研究院,兰州730000 [2]现代古生物学和地层学国家重点实验室(中国科学院南京地质古生物研究所),南京210008 [3]中国科学院大学,北京100049 [4]中国石油玉门油田分公司勘探开发研究院,甘肃酒泉735019 [5]中国石油勘探开发研究院西北分院,兰州730020

出　　处：《岩性油气藏》2021年第5期22-33,共12页Lithologic Reservoirs

基　　金：国家自然科学基金“酒西盆地早白垩世湖生浮游藻类及其与烃源岩发育和热流体活动的关系”(编号:41672137);现代古生物学和地层学国家重点实验室基金“酒西盆地下白垩统热水烃源岩分子生物标志物特征”(编号:183111)联合资助。

摘　　要：对酒西盆地下白垩统烃源岩的生烃潜力缺乏系统认识,并对其沉积古环境的认识也存在争议。通过对红柳峡地区下沟组烃源岩的孢粉相和元素地球化学的系统分析,研究烃源岩有机质母质来源、生烃潜力及其沉积古环境特征。结果表明红柳峡地区下沟组发育孢粉相A(植物碎屑—无定形组合),B(无定形组合)和C(植物碎屑组合)3类孢粉相,并且以孢粉相C为主;孢粉有机质整体以陆源高等植物来源的植物碎屑为优势成分,有机质类型主要为Ⅲ型,显示较差的生油潜力,其中下段和上段中的部分层位无定形含量较高,有机质为Ⅱ_(2)型,具有一定的生油潜力;下沟组沉积期为半潮湿—潮湿的气候,且具有晚期逐渐变潮湿的趋势,主要为氧化且生产力较低的微咸水—咸水环境,仅下段和上段中的部分层段表现为较深水的贫氧—缺氧沉积环境;红柳峡地区下沟组以近源冲积扇—三角洲和滨浅湖亚相沉积为主,其中早期和晚期沉积期水体稳定,发育部分较好的烃源岩,中期则发育近源氧化的三角洲—滨浅湖亚相沉积和较差的烃源岩。It is lacking on understanding of the hydrocarbon generation potential of the Lower Cretaceous source rocks in Jiuxi Basin,and it is also controversial on understanding of their sedimentary paleoenvironment.Based on the systematic analysis of palynofacies and element geochemistry of Xiagou Formation in Hongliuxia area,the source of organic matter,hydrocarbon generation potential and sedimentary paleoenvironment characteristics of source rocks were studied.The results show that three types of palynofacies,A(phytoclasts-amorphous assemblages),B(amorphous assemblages)and C(phytoclasts assemblages),are developed in Xiagou Formation in Hongliuxia area,and the palynofacies C is dominant.Phytoclasts from terrestrial higher plants dominate the palynological organic matter and the organic matter is mainly type Ⅲ,which shows poor oil-generating potential.The amorphous organic matter contents in some intervals of the lower and upper members are relatively high and the organic matter is type Ⅱ_(2),with some oil-generating potential.The element geochemical parameters indicate a semi humid-humid climate with a tendency of gradually humid in the late stage,and a mainly brackish-saline and oxic water environment with low productivity during the deposition of Xiagou Formation,and only some intervals in the lower and upper members were deposited in a suboxic-anoxic deep-water environment.The Xiagou Formation in Hongliuxia area is mainly composed of proximal alluvial fan-delta and shore shallow lake subfacies.In the early and late sedimentary period,the water body is stable,and some good source rocks were developed,otherwise,in the middle sedimentary period,proximal oxidation delta shore shallow lake subfacies and poor source rocks were developed.

关 键 词：元素地球化学 古环境 孢粉相 烃源岩 下沟组 红柳峡地区 酒西盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]