松辽盆地古龙凹陷青山口组页岩沉积环境特征及其有机质富集机理  

Geochemical Study of the Sedimentary Environment and Its Organic Matter Enrichment Mechanism in Qingshankou Formation Shale,Gulong Sag,Songliao Basin

作　　者：何文渊 蒙启安[2,3] 付秀丽 郑强[2,3] 苏杨鑫 崔坤宁[2,3] HE WenYuan;MENG QiAn;FU XiuLi;ZHENG Qiang;SU YangXin;CUI KunNing(Daqing Oilfield Co.Ltd.,PetroChina,Daqing,Heilongjiang 163002,China;Exploration and Development Research Institute of Daqing Oilfield Co.Ltd.,Daqing,Heilongjiang 163712,China;Heilongjiang Provincial Key Laboratory of Continental Shale Oil,Daqing,Heilongjiang 163712,China)

机构地区：[1]中国石油大庆油田有限责任公司,黑龙江大庆163002 [2]大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712 [3]黑龙江省陆相页岩油重点实验室,黑龙江大庆163712

出　　处：《沉积学报》2024年第5期1799-1816,共18页Acta Sedimentologica Sinica

基　　金：中国石油天然气股份有限公司重大科技专项(2021ZZ10)。

摘　　要：【目的】古龙页岩形成的古沉积环境是页岩油甜点预测的基础。【方法】通过松辽盆地现代湖盆水体盐度、古龙页岩的常微量元素、稀土元素及生物标志化合物等方法,深入研究了古龙页岩沉积环境的地球化学特征与有机质富集机理。【结果】古龙页岩形成时期气候整体温暖潮湿,发育淡水—微咸水还原环境,具有较高的古湖泊生产力,沉积速率低,水体较深,为有机质形成、保存与富集提供了地质基础。页岩沉积时期古气候指数CIA介于63~74,以温湿气候为主,页岩沉积时期古盐度w(Sr)/w(Ba)介于0.23~1.00,为淡水—微咸水环境,w(V)/w(V+Ni)介于0.6~0.9,以还原—强还原水体为主,古水深25~117 m,属于半深湖—深湖沉积,(La/Yb)N值在0.90和1.41之间浮动变化,代表较低的沉积速率。【结论】古龙页岩有机质富集主要受古气候、古盐度、古水深、沉积速率和古湖泊生产力等因素的有利耦合。研究成果可有效指导松辽盆地古龙页岩油甜点预测和勘探开发工作。[Objective]The paleosedimentary environment of the Gulong shale is the basis for the prediction of shale oil desserts.[Methods]Based on the salinity of modern lakes in Songliao Basin,the common and trace elements,rare earth elements,and biomarkers of the Gulong shale,the geochemical characteristics of the sedimentary environment and the enrichment mechanism of the organic matter were studied.[Results]The results show that during the formation of the Gulong shale,the climate was warm and humid,a freshwater brackish water reduction environment was developed,paleoproductivity was high,the sedimentational rate was low,and the water body was deep,which provided a geological basis for the formation,preservation,and enrichment of organic matter.The paleoclimate index,chemical index of alteration(CIA)during the shale deposition period was 63-74 and was dominated by a warm and humid climate.During the shale deposition period,the paleosalinity w(Sr)/w(Ba)was between 0.23-1.00,which was a fresh-brackish water environment,and w(V)/w(V+Ni)was between 0.6-0.9,a dysoxic-anoxic environment.The paleowater depth was 25-117 m,indicating a semi deep-to-deep lake deposition.The(La/Yb)N value fluctuated between 0.90-1.41,representing a low sedimentational rate.[Conclusions]The enrichment of organic matter in the Gulong shale was caused by the favorable coupling of paleoclimate,paleosalinity,paleowater depth,sedimentation rate,and paleoproductivity.The research results can effectively guide the prediction,exploration,and development of Gulong shale oil desserts in Songliao Basin.

关 键 词：古龙凹陷 页岩油 古气候 古盐度 古生产力 沉积速率 

分 类 号：P618.13[天文地球—矿床学]