典型含气页岩孔缝结构研究

发布时间：2018-03-05 13:04

本文选题：页岩气　切入点：有机孔　出处：《中国地质大学(北京)》2017年博士论文　论文类型：学位论文

【摘要】：页岩微孔隙、裂缝作为页岩储层中的主要储集、运移空间,一直以来是页岩气勘探开发中的研究重点。本次研究选取渝东南地区下古生界寒武系海相页岩、鄂尔多斯盆地侏罗系陆相页岩以及南华北盆地二叠系海陆过渡相页岩作为主要研究对象,采用了直接观察与物理测试相结合的方法对页岩的孔隙、裂缝发育特点进行了描述与对比,并建立了不同类型页岩的孔缝结构概念模型。在有机质类型和成熟度的控制下,下古生界海相页岩有机质中由于生烃形成的有机孔最为发育。由于侏罗系陆相页岩成熟度低,而二叠系过渡相页岩富含腐殖型有机质,因此有机质生烃孔并不多见。侏罗系陆相页岩中有机质孔隙大多为有机质保存自生物组织的结构孔,而二叠系过渡相页岩中多为有机质与附着在其中的粘土矿物之间的接触孔或收缩缝。三套具有不同成熟度的页岩镜下观察结果对比显示,页岩中与无机矿物相关的原生孔隙的发育程度整体随成熟度的升高而降低。过成熟的海相页岩中基本不含微米孔隙,残留的纳米级粒间孔、粒内孔与溶蚀孔都显示出接受过高压改造的痕迹。与成熟度保持一致的压实作用是决定页岩原生孔隙是否发育的重要因素。受区域构造运动的控制,下古生界海相页岩中高角度构造缝较为发育,水平裂缝多为顺层分布的矿物或有机质边缘的弱剥离面;侏罗系陆相页岩内裂缝主要为页岩与其中的粉砂质薄层之间的层理缝;二叠系过渡相页岩粘土矿物含量高,微观上粘土层间缝、收缩缝较为发育,宏观上多为不同岩性之间的层理缝。沉积环境控制的岩相组合与微结构是页岩沉积缝类型差异的重要原因。研究结果认为,下古生界海相页岩由有机孔-水平层理缝-高角度构造缝组成的孔缝系统易形成网络状运输通道,最有利于页岩气的储集与运移;侏罗系陆相页岩有机孔/粒内孔-粒间孔隙-水平层理缝孔缝系统,可以形成良好的水平运移通道;二叠系过渡相页岩中微小的粒内孔与大尺度岩性层理缝之间缺乏中等规模的连通通道,不利于页岩气的解吸与扩散。
[Abstract]:As the main reservoir and migration space of shale reservoir, shale micropore and fracture has been the focus of shale gas exploration and development. This study selects the Lower Paleozoic Cambrian marine shale in southeastern Chongqing. Jurassic continental shale in Ordos Basin and Permian transcontinental transitional shale in South North China Basin are the main research objects. Direct observation and physical test are used to study the porosity of shale. The characteristics of fracture development are described and compared, and the conceptual model of pore structure of different types of shale is established. The organic pores formed by hydrocarbon generation are the most developed in the organic matter of Lower Paleozoic marine shale. Because of the low maturity of Jurassic continental shale, the transitional shale of Permian is rich in humic organic matter. Therefore, the hydrocarbon generation pore of organic matter is rare. The pores of organic matter in Jurassic continental shale are mostly organic matter preserved from the structure pore of biological tissue. However, most of the transitional shale of Permian are contact pores or shrinkage joints between organic matter and clay minerals attached to them. The comparison of the three sets of shale microscopic observations with different maturity shows that, The degree of development of primary pores related to inorganic minerals in shale decreases with the increase of maturity. Both intragranular and dissolution pores show signs of overpressure transformation. Compaction consistent with maturity is an important factor in determining the development of primary pores in shale, which is controlled by regional tectonic movements. In the lower Paleozoic marine shale, the high-angle structural fractures are relatively developed, and the horizontal fractures are mostly weak exfoliation surfaces along the boundary of minerals or organic matter, while the inner fractures of Jurassic continental shale are mainly composed of stratified fractures between shale and the silty layers therein. The content of clay minerals in the transitional phase of Permian shale is high. The lithofacies combination and microstructure controlled by sedimentary environment are the important reasons for the difference of shale sedimentary fracture types. The porosity system of lower Paleozoic marine shale, which consists of organic pore, horizontal bedding seam and high angle structural joint, is easy to form network transportation channel, which is most favorable to the reservoir and migration of shale gas. A good horizontal migration channel can be formed in Jurassic continental shale organic pore / intergranular pore intergranular porosity horizontal stratified fracture fracture system. There is no medium scale communication channel between the tiny intragranular pore and the large scale lithologic seam in the Permian transitional shale, which is not conducive to the desorption and diffusion of shale gas.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P618.13

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