川南地区古生界构造特征及其对页岩气保存条件的影响

发布时间：2018-06-28 04:26

本文选题：川南地区 + 构造解释　；参考：《长江大学》2015年硕士论文

【摘要】：川南地区位于在四川盆地的东南部,夹持于华蓥山断裂带与齐岳山断裂带之间。该区东邻川黔断褶带、西邻川中隆起、北面与川东高陡隔档式构造带相连,但构造格局各不相同。作为四川盆地有利的页岩气富集带,发育有上二叠统龙潭组黑色泥页岩、下志留统龙马溪组页岩以及下寒武统筇竹寺组页岩三套海相优质烃源岩,是涪陵焦石坝探区获得重大突破后的重点接替区域。生烃是基础、保存是关键,有了优越的地质条件,保存条件成为了川南地区页岩气勘探开发的决定因素。对保存条件的研究需要以构造变形为先导,通过分析构造变形对储层的改造,从而导致不同构造保存条件的差异。因此开展川南地区构造特征的研究对指导川南页岩气的勘探和目标优选有十分重要的意义。通过收集川南地区丁山、赤水、荣昌-永川工区的钻井、测井、岩心资料及前人研究成果,结合野外地质观察与区域构造背景分析,运用Iandmark解释软件对工区范围内二维地震资料进行闭合解释,完成构造成图及相关图件制作,并进行下一步构造分析。川南地区构造形态主要以隔档式褶皱构造为主,发育逆断层,按照走向可分为北北东向、东西向、近南北向断层,在各自特定发育区域与边界基底断裂走向保持一致,整体表现为东南缘、西北部高,中部低。在川南大区域构造格架背景下,由面及点,对各工区进行构造特征研究：丁山构造是齐岳山大断裂带控制下的逆冲推覆构造,平面上整体形态表现为北西-南东方向鼻状背斜,剖面上表现为近齐岳山的盆缘推覆和盆内褶皱构造格局,发育有多种构造样式；林滩场构造同样受齐岳山断裂推覆控制作用明显,整体为一呈北东-南西向展布的长轴背斜构造,被5组北东-南西向断裂分隔,均为逆断层,多数断距较大,且延伸长度总体较长；赤水区域受两期构造运动影响,两组断层呈“十”字型相互切割限制,构造形态以短轴穹窿状背斜为主,受3套滑脱层影响,区内构造变形以盖层滑脱为主；荣昌-永川区块中部发育北东-南西走向背斜,东陡西缓,轴部断层发育,沿长轴方向展布,延伸长度较大,除盖层滑脱外还表现出双向逆冲的构造样式。结合区域构造构造应力场机制,再由点及面,综合各区断层的走向、规模、展布特征及褶皱的平面形态等组合特征及其分布规律,对川南地区进行构造体系划分为齐岳山冲断段、重庆弧形断褶带、赤水构造叠加带、永川弧形断褶带。选取合适地震剖面,通过构造演化分析,认为川南地区经历影响较大的3次构造运动：加里东—海西期以沉降为主的差异升降构造旋回形成区域上隆坳相间的古构造格局；印支运动时期,四川盆地由被动大陆边缘转入前陆盆地演化阶段,华蓥山形成隆起；晚燕山—喜山期由于东南部的挤压应力,以水平运动为主,产生了强烈褶皱、基底拆离、滑脱推覆等陆内造山运动。综合上述研究,对保存条件的研究应从构造运动对保存条件所产生的影响开始,基于差异构造变形,从断裂作用、上覆层厚度、顶底板有效性、构造样式四方面对川南地区采用综合指标量化加权评分排队的方法,进行页岩气保存条件进行综合评价。结果显示赤水区域宏观保存条件最好,其次为荣昌-永川,再次为林滩场,最后为丁山构造。
[Abstract]:The South Sichuan area is located in the southeast of the Sichuan basin, which is sandwiched between the Huaying Mountain Fault Zone and the Qi Yue mountain fault zone. The area is adjacent to the Sichuan Guizhou fault fold belt, the west is adjacent to the Middle Sichuan uplift, and the north is connected with the high and steep septum structural belt in East Sichuan, but the structure pattern is different. As the favorable shale gas accumulation zone in the Sichuan basin, the upper two series Longtan Formation is developed. The black shale, the lower shales of the Lower Silurian Long Ma Xi formation and the three sets of high quality hydrocarbon source rocks of the lower Cambrian shales are the key replacement areas after the major breakthrough in the exploration area of Fuling Jiao Shi dam. The hydrocarbon generation is the basis, the preservation is the key and the favorable geological conditions, and the preservation conditions have become the decision of the exploration and development of shale gas in the south of Sichuan. The study of the preservation conditions should be guided by structural deformation, and by analyzing the transformation of the tectonic deformation to the reservoir, which leads to the difference of the preservation conditions of different structures. Therefore, it is of great significance to conduct the study of the structural characteristics of the southern Sichuan area to guide the exploration and target optimization of the shale gas in South Sichuan. The drilling, logging, core data and previous research results of mountain, Chishui and Rongchang Yongchuan work area, combined with field geological observation and regional tectonic background analysis, using Iandmark interpretation software for closed interpretation of two-dimensional seismic data within the scope of the work area, complete structural mapping and related drawings, and carry out further structural analysis. The structural form is mainly composed of septum type fold structure and reverse fault. According to the trend, it can be divided into North and East, east-west, near North and South faults, consistent with the fault direction of the boundary basement, the southeast margin, the north-west high and the middle low. The structural characteristics of each area are studied. The Dingshan structure is a thrust nappe under the control of the large fault zone of the Qi Yue mountain. The whole form in the plane shows the nose shaped anticline in the North West to the South East. The section shows the tectonic pattern of the basin margin and the inner fold structure in the near Qi Yue mountain. There are many structural styles, and the forest beach field structure is also subject to Qi Yue. The thrust and overlay control of the mountain fault is obvious, and the whole is a long axis anticline structure with a north-east NW direction, divided by 5 groups of NSW faults, all of which are reverse faults, most of which are large, and the length of the extension is long. The Chishui region is influenced by two stages of tectonic movement, and the two groups of fault layers are restricted by the "ten" type, and the structure form is in structural form with the restriction of each other. The short axis dome like anticline is dominated by 3 sets of slipping layers, and the tectonic deformation in the area is mainly covered with caprock; the middle of the Rongchang Yongchuan block develops north east NW trending anticline, the East is slow and the axis faults are developed, the extension along the long axis, the extension length is larger, and the structural style of bi-directional thrust is displayed in addition to the slippage of the caprock. The tectonic stress field mechanism, then from the point and the surface, integrated the trend of fault, the scale, the distribution feature and the plane shape of the folds, and its distribution rules. The structural system of the southern Sichuan area is divided into the Qi Yue Mountain Thrust section, the Chongqing arc fault fold belt, the Chishui structural superposition zone and the Yongchuan arc fault fold belt. Over the tectonic evolution analysis, it is believed that the southern Sichuan area has experienced 3 tectonic movements: the Caledonian Hercynian differential tectonic cycle dominated by sedimentation and the formation of the paleotectonic pattern between the upland depressions, and the Sichuan basin from the passive continental margin to the foreland basin evolution period, and the Huaying Mountain Uplift. The late Yanshan - Himalayan period, due to the compressional stress in the southeastern part of the southeast, produced a strong fold, base detachment, and detachment and other intracontinental orogeny. The study of the preservation conditions should begin with the effects of tectonic movement on the preservation conditions, based on the differential tectonic deformation, from fracture action and overburden thickness. The results show that the best preservation conditions in Chishui region are the macro preservation conditions, followed by Rongchang Yongchuan, the second is the forest beach field, and the last is the Dingshan structure.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13;P548

【参考文献】