【作者】 张翔；

【导师】 田景春；

【作者基本信息】 成都理工大学 ， 沉积学， 2009， 博士

【摘要】 本论文以沉积学、层序地层学、石油地质学的理论为指导,以中国典型的海相碎屑岩储层层系-塔里木盆地志留系为研究对象系统开展沉积体系、层序地层学及其意义研究,为塔里木盆地志留系的进一步油气勘探提供重要的基础地质资料。充分利用盆地周缘野外剖面、钻井岩心资料、测井资料和室内测试分析资料,在沉积相标志研究的基础上,依据岩石组合、沉积组构、剖面结构和演化序列特征,在塔里木盆地志留系中识别出有障壁海岸、无障壁海岸、陆棚和辫状河三角洲沉积体系。其中有障壁海岸进一步划分为潮上、潮间和潮下微相,无障壁海岸识别出前滨和临滨微相,辫状河三角洲识别出辫状河三角洲平原、辫状河三角洲前缘和前三角洲微相。在对各沉积微相特征研究基础上,结合地震相平面分布规律,分别对塔里木盆地柯坪塔格组、塔塔埃尔塔格组、依木干他乌组沉积体系的平面分布及垂向演化特征进行了系统研究。并建立了塔里木盆地志留纪沉积演化过程中滨岸-陆棚的无障壁海岸沉积模式和潮坪-陆棚的有障壁海岸沉积模式。在精细沉积体系划分及沉积微相特征研究基础上,在塔里木盆地志留系野外剖面和钻井岩心中共识别出古风化壳、渣状层、超覆面、侵蚀冲刷面和岩性岩相转换面等多种类型的层序界面。依据沉积学、古生物学、地球物理及地球化学等标志,在上述关键界面识别基础上,将塔里木盆地志留系划分为12个三级层序。综合地震剖面之间的精确标定和对比,进行了区域层序地层对比及其格架建立。以上述沉积体系、层序地层学研究成果为基础,首次系统阐述了层序中层序界面与盆地构造演化特征、层序界面与油气运移和层序界面与有利圈闭形成的意义。鉴于上述层序界面所具有的重大意义,根据区域和局部地震资料解释成果,结合野外剖面及钻井标定,系统研究了塔里木盆地志留系各组之间的4个主要不整合面的接触关系和平面展布规律。首次对盆地层序格架中体系域的分布样式及差异性进行了系统研究,总结了塔里木盆地志留纪层序结构样式及其与沉积体系的响应关系,主要发育有:(1)TST>HST型层序充填样式,主要发育于滨海地区有障壁海岸和无障壁海岸中;(2)TST<HST型层序充填样式,主要发育在滨外陆棚区;(3)TST>HST—TST<HST之间的过渡型,主要位于滨海带与浅海带之间。根据体系域差异性分析了盆地构造演化及其充填历史。在对盆地志留系沉积体系、层序地层和岩相古地理研究基础上,依据二维、三维地震相研究成果,对层序格架中沉积体系充填特征及时空分配规律进行了详细研究。进而研究了塔里木盆地志留系烃源岩、储集岩和盖层的发育特征及时空分配规律。根据层序格架中的古地理展布特征、不同沉积相带发育的层序样式,建立了塔里木盆地志留系沉积-层序模式,并阐述了其油气地质意义。研究认为主要发育潮坪-陆棚和滨岸-陆棚沉积模式,由盆缘—盆地沉降中心具有TST>HST→TST=HST→TST<HST的层序发育样式。在盆地边缘TST发育潮下砂坪、潮道砂岩和前滨、临滨砂岩储集岩;HST发育潮上泥岩盖层。浅海陆棚区TST和最大海泛期发育深色陆棚相泥岩烃源岩,区域上亦为良好的盖层;HST发育砂坝及临滨砂体,为有利的储集岩。更多还原

【Abstract】 Based on the theory of sedimentology, sequence stratigraphy and petroleum geology, this dissertation take typical marine clastic reservoir- the Silurian strata in the Tarim Basin, northwest China, as its study object and sophisticated researches have been done for the depositional system, sequence stratigraphy and its study significance.These achievements would provide important basic information for further petroleum exploration in the basin.Based on the data collected from field outcrops, cores, logs and indoor tests, the depositional systems, including barrier shore system, open shore system and braided channel dominated deltaic system, are recognized in the Silurian strata of the basin. The barrier shore depositional system is further divided into supratidal, intertidal and subtidal facies, the open shore system into foreshore and shoreface facies, and the deltaic system into delta plane, delta front and prodelta facies. Thereby, with the aid of seismic data, we systematically studied the lateral and vertical transitional characteristics of the depositional systems of the Kepingtage Formation, the Tataaiertage Formation and the Yimugantawu Formation. Consequently, the depositional models of the Silurian in the Tarim basin have been established, which comprises the shore-shelf open marine model and the tidal flat-shelf barrier coast model.According to the facies characteristics, key surfaces that bound the systems tracts, such as weathering crusts, condensed sections, onlap-offlap surfaces, erosional surfaces and transitional surfaces of different lithologies are recognized. Then, the Silurian in the Tarim basin is divided into 12 third-order sequences. By comparison with seismic profiles, the regional sequence stratigraphic framework has been established.With respect to the established depositional systems and sequence stratigraphic framework, It was the first time to carry out the systematical study on the relationships between stratigraphic key surfaces and tectonics, conduits of oil and gas movement, and favorable traps.Then, the contacting relationships between the Silurian formations in the Tarim basin are presented.On the basis of the distributing pattern of systems tracts for the forst time, we sum up the corresponding relationships between the sequence stratigraphic framework and the depositional systems of Silurian in the Tarim basin as follow: (1) TST>HST sediment infilling pattern mainly develops in littoral zones with or without barrier; (2) TST<HST sediment infilling pattern mainly occurs in offshore zone; (3) transitional TST>HST–TST<HST infilling pattern that develops in-between the peritidal zone and offshore zone. The tectonics and infilling histories of the Tarim basin has been analyzed in terms of the characteristics of different systems tracts.Moreover, according our 2-D and 3-D seismic facies data, we have studies the spatio-temporal characteristics of the infilling of depositional system. The developmental features and spatio-temporal distribution of the source rocks, reservoir rocks and cap rocks are further presented for the Silurian in the Tarim basin.In the end, by synthesizing above outcomes, we come up with the deposition - sequence model for of Silurian strata in the basin as follow and expound its oil and gas exploration significance: the tidal flat -shelf and shore-shelf models are the best developed facies combinations, and from the margin to the depocenter, the sequences have the pattern of TST>HST-TST= HST-TST<HST. In the margin, subtidal sand-flat, tidal channel sandstone, foreshore and shoreface sandstone develop in TST, and supratidal mudstone, as cap rocks, occurs in HST. The source rock of shelf mudstone, develop in TST and the maximum flooding time ,both at shelf of offshore zone, is excellent blanket. the sandstone and shoreface sandstone, as good reservoir rock, develops in HST, which lies in shelf of offshore zone too.更多还原