【作者】 朱志军；

【导师】 陈洪德；

【作者基本信息】 成都理工大学 ， 沉积学， 2010， 博士

【摘要】 川东南地区志留系小河坝组(或石牛栏组)主要分布在四川盆地东南部有利天然气富集带上。建深1井小河坝组发现油气显示,及在川南-黔北的贵州习水地区的石牛栏组发现古油藏。并且小河坝组砂岩之下为早志留纪龙马溪组黑色笔石泥、页岩作为优质烃源岩,之上有巨厚的韩家店组泥、页岩作为良好的盖层,小河坝组具有优越的油气地质条件,因此,下古生界志留系具有良好的生储盖组合条件,且大面积被保存下来,埋藏适中,是四川盆地外围地区有利勘探区的目的层系。在如此较好的勘探前景下,研究区是否具有较好的油气储集体便成为了目前亟待解决的问题。为此,本文以沉积学、层序地层学为理论指导,以野外露头、钻/测井和测试分析资料为基础,充分结合前人研究成果,首先对川东南地区志留系小河坝组进行了物源、沉积体系、层序地层、层序岩相古地理研究,进而揭示该时期层序地层格架下的物质聚集分布规律及主控因素,为更有效地预测储层分布、储盖组合等提供理论依据。主要研究内容及成果有以下几个方面:(1)通过野外测量古流向、砂岩组分、重矿物、地球化学(稀土元素、微量元素)及砂体宏观展布特征研究,揭示了研究区的小河坝组的物源方向主要为265°～356°,即江南-雪峰山隆起是主要沉积物物源供给区。研究区小河坝砂岩源区的构造背景具有活动大陆边缘、大陆岛弧及被动大陆边缘的构造背景,母岩主要为抬升基底型更老的沉积岩再旋回沉积物。重矿物和地球化学分析结果表明川东南地区志留系小河坝组砂岩的物源为雪峰山隆起西侧的古丈、芷江、沅陵、怀化及通道一带的上元古界板板溪群及其侵入板溪群中的基性、超基性岩体、中基性喷出岩。(2)通过野外剖面、钻/测井相等相标志的详细研究,确定研究区共发育了2个沉积体系组、3个沉积体系,5个沉积相及众多亚相、微相类型。其中海陆过渡沉积体系组主要由三角洲构成,发育于靠近雪峰山隆起的川东南-湘西地区;海洋沉积体系组主要发育陆棚、碳酸盐台地沉积,主要分布于川南-黔北地区。(3)在层序界面识别的基础上,系统划分了川东南地区志留系小河坝组(石牛栏组)各级层序界面和层序,将志留系小河坝组(石牛栏组)划分为2个三级层序,4个四级层序,通过对重点剖面和井的层序地层划分对比,建立了相应的层序地层格架。(4)通过对等时层序地层格架内沉积体系演化的研究,明确了沉积体系在层序格架内的纵向上分布规律,研究表明小河坝期沉积物质主要发育于层序的高位体系域和海侵体系域;通过编制层序岩相古理图展示了沉积相的横向展布特征,进一步揭示了小河坝期物质聚集分布规律主要受控于构造活动、古地貌、物源供给、气候及海平面升降等因素。通过以上研究为指出四川盆地外围地区有利勘探层系提供理论依据。更多还原

【Abstract】 The lower Silurian Xiaoheba formation(Shiniulan formation)mainly distributed over the gas accumulation zone in southeastern Sichuan Basin. we found indication of oil and gas in well Jianshen 1, Paleooil reservoir of Shiniulan formation in Xishui ,south Sichuan-north Guizhou.Longmaxi formation consist of black mudstone,shale as the source rocks,which was covered by sandstone of Xiaoheba formation,and thick mudstone,shale of Hanjiadian formation as the seal rock. Xiaoheba formation prepared wide-area reservation,moderate burial,advantageous geology setting for becoming a good reservoir.In short Silurian of lower Palaeozoic had good conditions on the source-reservoir-seal associations.Under this advantageous exploration survey,the question about whether had effective reservoir or not must be solved immediately.This article based on sedimentology, sequence stratigraphy as theoretical direction, outcrop,data of well drilling and well logging, test analysis,combined with the result of research of predecessors.Using the provenance analysis and research of depositional system, sequence stratigraphy and Sequence-based lithofacies and paleography,in order to discover the rule accumulation and distribution of materials,and main controlling factors, provide theoretical basis for research of distribution of effective reservoirs and source-reservoir-seal associations,etc.This research contains content and results as follow:(1)By the field measurement of palaeocurrent direction,the research of sandstone components, heavy mineral, geochemistry(rare earth elements, trace elements),and the characteristics of macro distribution,in order to reveal that the provenance direction of sandstone of Xiaoheba formation mainly came from 265°～356°,(Jiangnan-Xuefengshan uplift was main provenance). Provenance consist of multi-cycle sedimentary rock,which came from older uplifted active continental margin and passive continental margin. We draw conclusion from the analysis of heavy mineral and geochemistry that the provenance came from the west wing of Xuefengshan uplift(Guzhang,Zhijiang,Yuanling,Huaihua),also involved basic rocks,ultrabasic rocks, basic-intermediate effusive rocks of upper Proterozoic Banxi group. (2)By the research of outcrop,drilling facies,logging facies,etc.There were two depositional system sets,three depositional systems,five sedimentary facies and types of parfacies,microfacies. Paralic sedimentary system sets mainly consisted of delta,which located near Xuefengshan uplift in southeast Sichuan-west Hunan. Marine depositional system sets mainly consisted of shelf, carbonate platforms,which mainly located in south Sichuan-north Guizhou.(3)Based on identified sequence boundaries, systematically divided two third-order sequences,four fourth-order sequences.Then we make comparison of the sequence of key sections and wells,in order to construct relative sequence stratigraphic framework of the Xiaoheba formation(Shiniulan formation)of lower Silurian in southeast Sichuan.(4)By the research of evolution of depositional system in the sequence stratigraphic framework,we make clear the rule of vertical distribution of depositional system,research shows that the deposition sequence of material of Xiaoheba formation, mainly developed in high system tract and transgressive systems tract. By mapping the map of lithofacies palaeogeography,in order to reveal the characteristics of spread of horizontal sedimentary facies. Further revealed the material of Xiaoheba formati on accumulation distribution is mainly controlled by tectonic activity, the ancient landscape, source supply, climate and sea level change and other factors.Based on above research,we can get the theoretical basis of favorable reservoirs of Silurian in southeast Sichuan.更多还原