【作者】 何卫军；

【导师】 李文厚；

【作者基本信息】 西北大学 ， 矿物学、岩石学、矿床学， 2007， 硕士

【摘要】 本文在前人研究成果基础上，综合应用层序地层学、沉积学、储层地质学等理论和方法，通过野外剖面观察、钻井岩心观察、测井资料解释、储层岩性物性分析等手段，对鄂尔多斯盆地南部侏罗系直罗组—安定组的沉积体系进行了较深入的研究，系统地分析了储集砂体及沉积微相的分布规律，最后总结归纳了盆地南部侏罗系直罗组—安定组的铀矿富集规律。运用层序地层学理论，结合前人研究成果，把侏罗系划分为7个三级层序，研究区内分别对应富县组、延安组延10～延7、延6～延4、延3～延1、直罗组、安定组和芬芳河组。对层序形成机制分析认为，气候、构造、海(湖)平面升降等因素不同程度地控制着侏罗纪沉积体系或体系域的进积和退积过程。根据古水流方向及砂岩成分分析认为，富县—延安组沉积时，盆地东部地区的物源主要来自盆地北部与西北部的侵蚀区；直罗-安定组具有多物源的特点。运用沉积学和沉积相分析的理论，通过分析相标志，完成了单井微相划分和沉积相纵横向剖面对比，认为盆地南部目的层主要发育冲积扇、河流、湖泊、三角洲4种沉积体系，论述了各层位的主要沉积相特征。其中直罗组辫状河及辫状河三角洲是主要铀矿储层，延安组河流相也有部分铀矿化。探讨了盆地南部侏罗系沉积相展布及古地理演化。延安组沉积之后盆地经历短暂抬升，呈现东高西低的分布格局。直罗组沉积厚度大，整体表现出低位体系域的特点，主要以河流体系为主，发育湖泊沉积。安定组古地理面貌与直罗组沉积具有一定的继承性。但由于地壳下沉，在盆地东南部再次发生大规模湖侵，特别是晚期湖水加深，沉积了厚度较大的泥灰岩。从前人的工作来看，研究区具备形成砂岩型铀矿的配置条件，对于形成层间氧化带砂岩型铀矿是非常有利的，当前任务主要是寻找有利相带和优质储层分布区。根据沉积相发育、砂体展布、已有的钻孔资料、野外露头，结合底面埋深，并考虑到工业生产的情况，提出下一步应该重视的有利地区。对于直罗组应继续重视惠安堡及店头地区，并加大西南部的彬县-旬邑地区的勘探力度。更多还原

【Abstract】 Based on the present research results, Applied with outcrop observation, core description, geophysical logging interpretation, reservoir lithology and physical property analysis and other analytic machinery, and general applied with sequence stratigraphy, sedimentology, reservoir geology theory and methods, the sedimentary system of Zhiluo-Anding Formation in the southern of the Ordos basin are studied deeply, the distribution rule of reservoir sand bodies and sedimentary microfacies are analyzed totally, and generalized the concentration regularity of uranium mine in Zhiluo-Anding Formation in the southern Ordos basin by the end.Applied the theory of sequence stratigraphy and connected with the predecessors research results, seven tertiary sequences were classified in Jurassic, differently correspond to Fuxian Formation, yan10～yan7, yan6～yan4, yan3～yan1,Zhiluo and Anding Formation. According to formation mechanism of sequence analysis, it was seen that the sedimentary system of Jurassic or the process of progradation and retrogradation of system tract were differently controlled by climate, structure, lake level fluctuation (eustasy) etc.Analyzing the paleocurrent direction and the component of the sandstone considered that the material source in the eastern Ordos basin in Fuxian-Yan’an Formation mainly came form the corrosive areas in the northern and northwestern of the basin, and it was a characteristic of multisource in Zhiluo-Anding Formation.Applied the theory of sedimentology and sedimentary facies and analyzed the facies marker, the classification of single well microfacies and the profile correlation of longitudinal section and cross section had been done. Four types of sedimentary systems were developed in this area, that was, fan delta system, stream system, lake system and delta system in the target, and discussed the characteristics of major sedimentary facies in each horizon. Braided-river and braided-river delta system in Zhiluo Formation was the main reservoir of uranium mine, and uranium mineralization was also discovered in the fluvial facies in Yan’an Formation.The distribution of sedimentary facies and palaeogeographic evolution were discussed in this paper. The basin came through a temporary uplift and the geomorphology was higher in the eastern part and lower in the western part. The thick sedimentary thickness displayed the characteristic of lowstand system, the stream system was the main system and lake sediment was familiar too. The paleogeomorphy of Anding Formation is of a certain inherited character with Zhiluo Formation. But because the crust sinking, lake-transgressive system happened again in the southeast basin, especially lake deepening at late stage, thick chalky clay was deposited.Based on the present research results, research area belonged to the situation of coming into being sandstone type uranium deposits, it was very advantaged for coming into being oxidized zone sandstone type uranium deposits in interlamination, finding the favorable phase and the area of high-quality reservoirs were the current main mission. According to the characteristics of sedimentary facies, the distribution of sandbodies, the drill data, the field outcrop, coalesced buried depth of back surface and considered the situation of industrial production, the favourable place should be paid great attention next was presented. For Zhiluo Formation, Hui’anbao and Diantou area should be paid great attention continue, and increment of deep exploration for Binxian-Xunyi area in the southwest was also important.更多还原