摘要
西西伯利亚盆地上侏罗统-下白垩统巴热诺夫组硅质-钙质富有机质泥页岩总有机碳(TOC)含量高且有机质成熟度适中,是俄罗斯目前页岩油的勘探首选目的层系。近年研究表明,该套富有机质页岩层段发育数套厘米-毫米级的火山灰夹层,具黄色荧光,岩心薄片见大量沸石等火山灰蚀变矿物,使该区火山灰与富有机质形成的相互关系引起关注。以该盆地的巴热诺夫组为例,介绍了火山灰对该区富有机质页岩形成的影响。巴热诺夫组的地质-地球化学分析表明,在火山灰发育同期沉积的富有机质层段中不仅硅、磷等营养元素含量高,而且钡、锰、钼、铀等藻类繁殖催化元素含量也高,推测火山灰携带物质促进了巴热诺夫页岩沉积时期古生物的大量繁殖甚至爆发,为富有机质的形成奠定了物质基础;同时,在火山灰发育层段之上的富有机质泥页岩中大量发育草莓状黄铁矿,且呈层状分布,Co/Ni比值小于1,S/Fe比值偏高,指示火山灰喷发之后形成缺氧的强还原环境,有利于泥页岩中有机质的保存;火山灰发育井区TOC含量高(多>7%),有机质成熟度与邻近火山灰不发育区相比偏高(R o=0.7%~1.1%),生烃潜力高且已达到生油高峰,推测可能火山灰携带的钼、镍等元素促进了热催化生油阶段干酪根的成烃演化;火山灰发育的富有机质页岩层段常见藻类纹层与碳酸盐岩纹层互层,多见层间孔缝,利于页岩油气的运移。因此,火山灰与巴热诺夫组富有机质页岩的形成具有一定的内在联系,火山灰不仅能够提高沉积时期的古生产力和保存条件,促进有机质的成烃演化,而且利于形成富有机质交互纹层,易于后期压裂开发。
The siliceous and calcareous organic-rich shale in the Upper Jurassic-Lower Cretaceous Bazhenov Formation in West Siberian Basin is characterized by high TOC and organic matters of moderate maturity and therefore has been the preferred shale oil exploration target in Russia.Recent study reveals several sets of centimeter to millimeter thick volcanic ash interlayers with yellow fluorescence in this organic-rich shale interval.A large number of volcanic ash-altered minerals such as zeolite are also detected through thin section observation,thus triggering an interest in the investigation of the relationship between volcanic ash and organic matter in this area.This study takes the Bazhenov Formation in the basin as an example to illustrate the influence of volcanic ash on the formation of the organic-rich shale.The composite geological-geochemical analysis on the volcanic ash in the formation shows that the organic-rich shale deposited synchronously with volcanic ash is rich in both nutrients such as silicon and phosphorus and catalytic elements for algae multiplication such as barium,manganese,molybdenum and uranium.It is therefore speculated that materials carried by volcanic ash promoted the mass reproduction or even facilitated a boom of palaeobios during the deposition of the Bazhenov,laying a material foundation for the formation of organic-rich matters.At the same time,a large number of strawberry-like pyrite layers were also developed in the shale overlying the volcanic ash interval,against a strong reducing enviroment of oxyen deficiency after volcanic ash eruption with Co/Ni ratio less than 1 and high S/Fe ratio.The fact that samples from the area with well-developed volcanic ash layers were measured to have higher TOC(over 7%)and maturity(Ro ranging between 0.7% and 1.1%)as well as higher hydrocarbon-generation potentials(almost reaching the peak)than those from adjacent areas without the layers indicates that the elements such as molybdenum and nickel carried by the volcanic ash served to promote the hydrocarbon generation of kerogens during thermocatalysis.The algal laminae interbedded with carbonate laminae in the shale could create plenty of interlayer pores for the migration of oil and gas.The formation of organic-rich shale in the Bazhenov Formation is,to some extent,inherently related to volcanic ash,which probably served to improve the paleo-productivity and preservation conditions for organic matter during the deposition period,promote the early hydrocarbon generation of organic matters,and facilitate the formation of organic-rich interlayers that respond quickly to stimulation operations.
作者
梁新平
金之钧
刘全有
Shpilman Alexander
李鹏
Morozov Vladimir
Uspensky Boris
Liang Xinping;Jin Zhijun;Liu Quanyou;Shpilman Alexander;Li Peng;Morozov Vladimir;Uspensky Boris(Energy Research Institute,Peking University,Beijing 100871,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 100083,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;V.I.Shpilman Research and Analytical Center for the Rational Use of the Subsoil,Autonomous Institution of Khanty-Mansiysk Autonomous Okrug-Yugra,Tumen 625026,Russia;Institute of Geology and Petroleum Technologies,Kazan Federal University,Kazan 420008,Russia)
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2021年第1期201-211,共11页
Oil & Gas Geology
基金
国家自然科学基金委重大项目(42090025,42090020)
国家重点研发计划项目(2019YFA0708504)
国家自然科学基金项目(41811530094,41625009)。
关键词
藻类勃发
还原环境
成烃演化
富有机质形成
火山灰
页岩
巴热诺夫组
中生界
西西伯利亚盆地
algae boom
reducing environment
hydrocarbon generation
formation of organic-rich matters
volcanic ash
Bazhenov Formation
Mesozoic
West Siberian Basin
