鄂尔多斯盆地中南部长7段泥页岩系的埋藏成岩—孔隙演化过程

发布时间：2018-05-26 00:13

  本文选题：成岩作用 + 孔隙结构　； 参考：《西北大学》2017年硕士论文

【摘要】：页岩气储层成岩作用过程、孔隙特征和孔隙演化规律的研究,能够为分析页岩气储层储集性能、探讨页岩气赋存成藏过程和机理、预测页岩气“甜点区”提供指导。因此,如何准确全面地剖析泥页岩成岩作用过程、表征泥页岩储集层孔隙结构特征和判断泥页岩孔隙空间在埋藏成岩过程中的演化规律成为储集层研究的重要基础问题。然而,目前对泥页岩成岩作用的研究十分薄弱,页岩气储层孔隙体系尚未形成统一的分类方案,泥页岩纳米级孔隙的表征方法也在探索之中,不同类型的孔隙在不同埋藏成岩阶段的演化规律尚不明确。鄂尔多斯盆地上三叠统延长组长7段泥页岩既是盆内优质烃源岩,又是有利的页岩气储层。本文在充分调研和总结国内外学者研究成果的基础上,针对鄂尔多斯盆地中南部延长组长7泥页岩,采用氩离子抛光-场发射扫描电镜观察、气体吸附、电子探针、X-射线衍射、镜质体反射率(Ro)测定和岩石热解等多种分析测试手段,系统研究了长7泥页岩岩石组合类型、矿物学和有机地球化学等特征,分析泥页岩成岩作用类型及演化过程,明确长7泥页岩孔隙类型及孔隙结构特征,探讨影响泥页岩孔隙发育和演化的主要因素,总结并建立泥页岩在埋藏成岩过程中孔隙的演化规律和模式。研究成果表明:长7泥页岩以黏土质泥岩和硅质泥岩为主,其中广泛发育粉砂质纹层;矿物组成复杂多变,富含黏土矿物、石英和长石,碳酸盐含量较低;有机质含量集中分布在3%～6%之间,有机质类型以Ⅱ型干酪根为主,有机质的镜质体反射率Ro集中分布在0.8%～1.0%之间。长7泥页岩经历了压实作用、胶结作用、溶蚀作用、矿物转化成岩作用和有机质热演化生烃作用共同改造,普遍进入中成岩A期;成岩序列为黄铁矿、菱铁矿→方解石Ⅰ →绿泥石Ⅰ →溶蚀作用Ⅰ →自生石英Ⅰ、高岭石→伊蒙混层→溶蚀作用Ⅱ→绿泥石Ⅱ→伊利石、自生石英Ⅱ→铁白云石、方解石Ⅱ。长7泥页岩孔隙类型多样,包括粒间孔、粒内孔、晶间孔、有机质孔隙和裂缝孔隙,其中粒间孔隙和裂缝孔隙是最重要的孔隙类型,其它类型的孔隙相对不发育。孔隙形态复杂,整体上以平板狭缝形和楔形为主;孔径分布范围宽泛(0.1nm～1OOOOnm),孔隙度为0.5%～6.6%,中孔(2～50nm)和宏孔(50nm)是孔隙度的主要贡献者。岩相类型、成岩作用、有机质热演化生烃作用和构造作用是影响研究区长7泥页岩孔隙发育及演化的四个主控因素,岩相是控制孔隙发育和演化的先决条件,并影响着埋深过程中热演化生烃作用、成岩作用的演化过程。成岩作用、热演化生烃作用、构造作用相互影响、共同控制着埋藏过程中泥页岩孔隙的发育和演化。长7段泥页岩基质孔隙的演化具有一定的规律性:埋深1000m的浅埋藏条件下,为孔隙度急剧降低阶段;埋深在1000～2000m条件下,为孔隙度降低速率相对缓慢阶段;持续下降的最大埋深至后期抬升至现今埋深,孔隙度缓慢降低-基本保持稳定。
[Abstract]:The study on the diagenesis, pore characteristics and pore evolution of shale gas reservoirs can be used to analyze the reservoir performance of shale gas reservoirs, to explore the accumulation process and mechanism of shale gas accumulation, and to predict the "dessert zone" of shale gas. Therefore, how to accurately and comprehensively analyze the process of shale formation and characterization of shale reservoir pores. The structural characteristics and the evolution of shale pore space in the process of buried diagenesis have become an important basic problem in the study of the reservoir. However, at present, the study of shale formation is very weak. The pore system of shale gas reservoirs has not yet formed a unified classification scheme, and the characterization method of the shale nanoscale pores is also being explored. The evolution law of different types of pores in different buried diagenesis is not clear. The 7 section of Yanchang group Chang Group Chang of the upper three series of Ordos Basin is not only the high quality hydrocarbon source rock in the basin, but also a favorable shale gas reservoir. Lengthening the group 7 shale, using argon ion polishing and field emission scanning electron microscopy, gas adsorption, electron probe, X- ray diffraction, vitrinite reflectance (Ro) and rock pyrolysis, and other analysis and testing methods, the characteristics of rock assemblage, mineralogical and organic geochemistry of long 7 shale are systematically studied, and the diagenesis of shale is analyzed. The type and evolution process, clear the pore type and pore structure characteristics of long 7 shale, discuss the main factors that affect the pore development and evolution of shale, summarize and establish the evolution law and model of pore in the process of shale in the process of buried diagenesis. The research results show that the long 7 shale is mainly clay mudstone and siliceous mudstone. The mineral texture is complex and changeable, the content of clay minerals, quartz and feldspar is low, the content of organic matter is concentrated between 3% and 6%, the type of organic matter is dominated by type II kerogen, and the vitrinite reflectance Ro of organic matter is concentrated between 0.8% and 1%. 7 shale has undergone compaction and cementation. Dissolution, transformation of minerals into rock and organic matter thermal evolution and hydrocarbon generation, generally entered the A stage of the middle diagenesis; the diagenetic sequence is pyrite, siderite, calcite I to chlorite I to corrosion I to self authigenic quartz I, kaolinite to immont, corrosion II, chlorite II to illite, and authigenic Shi Ying The pore types of the long 7 shale are varied, including intergranular pores, intragranular pores, intergranular pores, organic pores and fissure pores, among which intergranular pores and fissure pores are the most important pore types, and other types of pores are relatively undeveloped. The wide range (0.1nm to 1OOOOnm), porosity of 0.5% to 6.6%, mesopore (2 ~ 50nm) and macropore (50nm) are the main contributors to porosity. The lithofacies type, diagenesis, hydrocarbon generation and tectonic action of organic matter are four main controlling factors affecting the pore development and evolution of the study area 7 shale, and the lithofacies are the control of pore development and evolution. The precondition of chemical evolution has a certain regularity in the evolution of shale pores in the long 7 segments of the shale. The evolution of the pore space in the long 7 segments of shale has a certain regularity: shallow depth of the buried depth of the shale. Under the conditions of burial, the porosity is sharply reduced, and the depth of the buried depth is relatively slow under the condition of 1000 to 2000m, and the maximum depth of continuous descent is raised to the present depth, and the porosity slows down slowly - basically stable.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13
，

本文编号：1935202