渝东南地区下古生界页岩层系构造特征与页岩气保存条件研究

发布时间：2018-03-10 06:20

本文选题：构造特征　切入点：保存条件　出处：《西南石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,页岩气的勘探开发饱受关注,川渝黔地区成为页岩气开发主战场。本文重点研究渝东南地区下古生界五峰组-龙马溪组页岩构造特征和页岩气保存条件,并初步预测保存有利区块,为五峰组-龙马溪组下一步勘探提供依据。在6条野外剖面观测和4口井岩心观察描述的基础上,结合区域构造背景分析,系统论述渝东南地区五峰组-龙马溪组页岩层系构造特征,五峰组-龙马溪组页岩气藏的保存条件。研究表明渝东南地区受到加里东运动、印支运动、燕山运动及喜山运动等多期构造作用。该区构造变形特征以挤压变形为主,兼有走滑的性质,褶皱和断裂构造非常发育,褶皱整体上以北东向、北北东向展布为主,且褶皱的轴面倾向南东居多。由北西向南东,褶皱依次为隔挡式褶皱、城垛状褶皱、隔槽式褶皱。渝东南地区有北东向、北北东向、北西向、南北向四组断裂体系,断裂以北东向和北西向为主,且倾角较大。渝东南地区构造裂缝主要为剪性裂缝、张剪性裂缝,滑脱缝等。优势方位为北东向,倾角较小。通过岩心裂缝观察描述,总体上裂缝长度越大,宽度较小,倾角较大。构造作用影响裂缝发育程度,构造裂缝经常与褶皱和断裂伴生,并且裂缝发育与地层厚度和岩性等有关,地层厚度越小,裂缝间距相对也较小。页岩气的保存条件受到自身厚度、盖层、顶底板条件、构造运动、构造样式等因素的影响。渝东南地区五峰-龙马溪组页岩北部较厚,东西部和南部较薄。研究区上覆区域盖层发育较完整,志留系-中下二叠统泥岩、中下三叠统泥岩和膏岩都可作为研究区有效的区域盖层。作为直接覆盖在龙马溪组之上的罗惹坪组为一套粉砂岩、粉砂质页岩,裂缝不发育,是龙马溪组较好的顶板,而下伏的宝塔组或临湘组是一套瘤状泥质灰岩,质地坚硬,是良好的底板。燕山期以来渝东南构造运动强烈,导致整个地区变形严重,地层较陡,裂缝发育。页岩气保存较好的地区为构造运动相对较弱的地方。根究上述研究区构造特征及保存条件评价指标,划分出武隆县北西等6个I类和黔江以西等10个II类保存条件有利区块。
[Abstract]:In recent years, the exploration and development of shale gas have received much attention, and the Sichuan, Chongqing and Guizhou regions have become the main battlefields of shale gas development. This paper focuses on the shale structural characteristics and shale gas preservation conditions of the lower Paleozoic Wufeng formation and Longmaxi formation in southeastern Chongqing. The favorable blocks are preliminarily predicted to provide basis for further exploration of Wufeng formation-Longmaxi formation. On the basis of 6 field profile observations and 4 core observations, combined with regional tectonic background analysis, this paper systematically discusses the structural characteristics of shale series of Wufeng formation and Longmaxi formation in southeastern Chongqing. Preservation conditions of shale gas reservoirs in Wufeng-Longmaxi formation. The study shows that the southeast of Chongqing is subjected to the Caledonian, Indosinian, Yanshanian and Himalayan movements. The tectonic deformation in this area is characterized by compressional deformation and strike-slip, and the fold and fault structures are well developed. On the whole, the fold is mainly distributed north to east and north to east, and the axial plane of the fold tends to be mostly south to east. From north to west to south to east, the fold in turn is a blocking fold, a battlements fold, and a trough fold. There is a north east direction, a north east direction in the southeast of Chongqing, and a north east direction, a north east direction, a north east direction. There are four fault systems in NW, NNE, NW and NW, and the inclination is larger. The structural fractures in southeastern Chongqing are mainly shear fractures, tensional shear fractures, slippage fractures, etc. The dominant azimuth is northeastward and the dip angle is small. By observing and describing the core fractures, the larger the length and the smaller the width, the larger the fracture length, the smaller the width. The tectonic action affects the degree of fracture development. Structural fractures are often associated with folds and faults, and the development of fractures is related to formation thickness and lithology. The smaller the formation thickness, the smaller the fracture spacing. The preservation conditions of shale gas are affected by its thickness, caprock, roof and bottom plate, tectonic movement, structural style, etc. The north of Wufeng-Longmaxi formation is thicker in southeast Chongqing. The overlying area of the study area is relatively intact, and Silurian-middle and lower Permian mudstone, The middle and lower Triassic mudstone and gypsum can be used as effective regional caprocks in the study area. As a set of siltstone, silty shale and undeveloped fractures, Luojaping formation, which directly covers the Longmaxi formation, is the better roof of the Longmaxi formation. The underlying Baota formation or Linxiang formation is a set of nodular muddy limestone with a hard texture and a good bottom plate. Since the Yanshanian period, the tectonic movement in southeast Chongqing has been strong, resulting in serious deformation and steeper strata in the whole area. The area where shale gas is well preserved is where the tectonic movement is relatively weak. On the basis of the structural characteristics and the evaluation index of preservation conditions in the study area mentioned above, there are 6 classes I and 10 favorable blocks of type II preservation conditions in the north west of Wulong County and the west of Qianjiang River.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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