城口下古生界页岩层系构造特征与页岩气成藏条件研究

发布时间：2018-05-13 07:08

本文选题：城口 + 页岩层系　；参考：《成都理工大学》2017年硕士论文

【摘要】：论文研究区位于重庆市城口县,重庆地区经历的构造沉积演化有三个阶段,扬子准地台基底生成阶段(晋宁期)、地台演化阶段(南华纪-三叠纪)、陆内改造阶段(侏罗纪-第四纪),城口地区的沉积岩从新元古界明月组到第四系地层都有出露(除泥盆系、石炭系和古、新近系缺失外)。以城口地区寒武系下统水井沱组/鲁家坪组页岩为对象,分析页岩层系构造特征与成藏条件,这对城口地区页岩气的后期勘探工作具有参考价值。大巴山弧形构造带以城口断裂作为界线进行构造单元划分:北大巴逆冲推覆构造带、南大巴复合前陆褶皱-冲断带,本文根据不同构造单元、构造样式、褶皱特征、断裂及裂缝特征进行研究分析。研究区经历了多期构造运动,形成近东西向,北西-南东向密集分布、大体平行、不对称的褶断构造系。构造线总体呈北西-南东向展布,受多期构造作用的叠加,断层相互交切,褶皱多被断层破坏,褶皱形态复杂,样式主要表现为复式褶皱;断层十分发育,以逆冲断层为主,城口断裂北的构造特征是褶皱和断层发育形成的反冲构造系统,形成许多纵断裂,往北西向延伸在两端被城口断裂截切,城口断裂以南的主要构造特征是逆冲褶皱组合,总体构造特征为明显的破裂、变形强度自北东-南西递变减弱的有序性、分带性。页岩气具有吸附性特征,具有一定抗破坏能力,城口地区处于盆地边缘,构造破坏强烈,抬升剥蚀作用、地层产状、褶皱构造、断裂及裂缝的发育程度对页岩气的成藏有较大影响。研究区在地质历史时期,经历了多期次的构造改造,与褶皱伴生的断裂十分发育,以北西-南东向的逆冲断层为主,且具多期断层作用的叠加,相互切割、错位,造成大量的地层缺失,并派生出一系列的次级断层构造,造成含气层与顶、底板多为断层接触,对页岩气的储存产生了较大的破坏作用。通过野外采集样品进行了高分辨率电镜扫描图像分析、薄片微观结构和矿物成分鉴定等实验得出数据,分析富有机质页岩有机碳含量、有机质成熟度、有机质类型特征,进一步对城口地区下古生界页岩层系构造特征和页岩气成藏条件的探讨分析。
[Abstract]:The research area of this paper is located in Chengkou County, Chongqing, which has experienced three stages of tectonic and sedimentary evolution. Yangzi quasi platform basement generation stage (Jinning period), platform evolution stage (Nanhua-Triassic), intra-continental reconstruction stage (Jurassic-Quaternary), Chengkou sedimentary rocks from the Neoproterozoic Minyue formation to the Quaternary strata Exsertion (except for Devonian, Carboniferous and Paleozoic, Neogene are missing. Taking the Lower Cambrian Shale of Shuituo formation / Lujiaping formation in Chengkou area as an example, the structural characteristics and reservoir forming conditions of shale strata are analyzed, which is of reference value for the later exploration of shale gas in Chengkou area. The arc-shaped tectonic belt of Dabashan is divided into structural units with Chengkou fault as the boundary: the North Daba thrust nappe belt, the South Daba complex Foreland fold thrust belt, according to different tectonic units, structural styles, fold characteristics, etc. Fracture and fracture characteristics are studied and analyzed. The study area has undergone multiple tectonic movements, forming a nearly east-west, NW-SE dense distribution, roughly parallel, asymmetric fold tectonic system. The tectonic lines are generally NW-SE, superimposed by multiple tectonic processes, faults intersecting, folds are destroyed by faults, fold forms are complex, their patterns are mainly complex folds, faults are well developed, and thrust faults are the main faults. The structural characteristics of the north Chengkou fault are the recoil structural system formed by fold and fault development, forming many longitudinal faults, and extending northwestward by the Chengkou fault at both ends. The main structural feature of the south of Chengkou fault is the thrusting fold assemblage. The overall structural characteristics are obvious rupture, the deformation intensity is gradually weakened from the north east to the south west, and it is orderly and zonation. Shale gas has the characteristics of adsorption and anti-failure. Chengkou area is on the edge of the basin, with strong structural damage, uplift and denudation, stratigraphic occurrence and fold structure. The fault and the development degree of fracture have great influence on the formation of shale gas reservoir. In the period of geological history, the study area experienced many periods of structural transformation, and developed well with the faults associated with the fold. The thrust faults in the north west to south east direction were the main ones, and they were superimposed by the action of multiple phases of faults, cutting and displacing each other. A large number of strata are missing, and a series of secondary fault structures are derived, resulting in the contact between gas bearing strata and top and bottom plates, which has a great destructive effect on shale gas storage. High resolution electron microscope scanning image analysis, slice microstructure and mineral composition identification were used to analyze the organic carbon content, maturity and type of organic matter in organic shale. The structural characteristics of the Lower Paleozoic shale strata and the reservoir forming conditions of shale gas in Chengkou area are discussed and analyzed.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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