四川盆地东缘五峰—龙马溪组页岩岩相特征研究

发布时间：2018-05-19 22:13

本文选题：五峰-龙马溪组 + 页岩岩相　；参考：《成都理工大学》2015年硕士论文

【摘要】：页岩岩相的划分方式有按沉积构造划分,按矿物组成划分以及结合沉积构造和矿物组成划分三种方式。本文选取按沉积构造来划分页岩岩相。页岩沉积构造中又以纹层最为容易识别和分类。所以本文选取从四川盆地东缘巫溪1井,焦石坝地区的X井和Y井,以及秀山溶溪地表剖面3处剖面的五峰-龙马溪组页岩样品进行显微镜观察分析,观察到块状页岩、平行纹层页岩、不平行纹层页岩3类主要的页岩岩相,以及斑状纹层页岩、透镜状纹层页岩和粒序纹层页岩这几种分布不太广泛的页岩岩相。薄片下观察到,块状页岩的纹层最不明显,平行纹层页岩的纹层细长而平直,不平行纹层页岩的纹层则粗壮且相互呈低角度相交。纹层中主要矿物为石英、白云母、长石、方解石、白云石等脆性矿物,周围基质中则以黏土矿物占多数。五峰-龙马溪组页岩3种主要的页岩岩相在矿物组成上有明显的区别。按照块状页岩、平行纹层页岩以及不平行纹层的页岩的顺序,平均石英含量依次降低,分别为61%、50%、32%,平均黏土矿物含量依次升高25.8%、29.1%、53.2%。石英含量与TOC呈正相关,黏土矿物含量与TOC呈负相关。就矿物组分来说,块状页岩和平行纹层页岩的页岩气储集物性要优于不平行纹层页岩。扫描电镜可以观察到纹层的细微特征,矿物的定向排列尤为明显。四川盆地东缘五峰-龙马溪组页岩主要发育粒间格架孔、黏土片间孔、粒缘孔、莓球状黄铁矿粒内晶间孔、黏土粒内孔、成岩溶孔、有机质孔以及微裂缝8类微观孔隙。虽然五峰-龙马溪组页岩不同页岩岩相所经历的成岩后生作用差别不是太大,演化程度也差不多。但其初始沉积条件的不同导致了他们的微孔分布特征有一定的差别。有机质孔和莓球状黄铁矿粒内晶间孔在块状页岩中最为发育,而不平行纹层页岩中粒间格架孔和黏土片间孔更占优势。就有机质类型而言,3类主要页岩岩相的有机质主要属于腐泥型(I)到腐殖-腐泥型(II1)。TOC的含量为块状页岩高于平行纹层页岩高于不平行纹层页岩。三条剖面所有样品统计显示,块状页岩TOC为3.7%,平行纹层页岩TOC为3.4%,不平行纹层TOC则只有1.1%。四川盆地东缘五峰-龙马溪组页岩样品的主微量数据显示,3类主要页岩岩相的脆性程度都与TOC呈正相关。微量数据显示,块状页岩和平行纹层页岩的水体环境主要为缺氧到贫氧,而不平行纹层页岩的水体环境主要为贫氧到氧化。不平行纹层页岩所反映的水动力环境要强于块状页岩和平行纹层页岩。3种主要岩相所反映的海水古盐度均为微咸水,但块状页岩和平行纹层页岩所代表的古水深是明显大于不平行纹层页岩的。块状页岩代表了一种稳定的沉积环境,沉积速率可快可慢,可以形成于水下峡谷或者陆棚上水体较深的区域这些沉积速率高的地方,也可以形成于水体相对安静,沉积速率低,悬浮作用沉积的地区,关键是没有明显的沉积间断。笔者认为页岩中纹层的出现代表了一种与河流周期性洪水有关(间歇性的悬浮沉积)的环境,平行纹层页岩代表了这种季节性(或周期性)洪水不太猛烈的环境,使得洪水期沉积的层和非洪水期沉积沉积层界限明显平直,侵蚀作用较轻。不平行纹层页岩的纹层较平行纹层的粗,可能反映了更加剧烈的周期性洪水。洪水带来的沉积物明显受到了底流、波浪或潮汐的改造。至于横向上三条剖面/井所反映的主要岩相分布的差异,可能与剖面在陆棚中的位置有关。因为较高的TOC,石英含量以及大量发育的有机质孔,块状页岩和平行纹层页岩对于页岩气勘探开发的意义明显大于不平行纹层页岩。
[Abstract]:There are three ways of dividing shale facies according to the sedimentary structure, dividing according to mineral composition and dividing the sedimentary structure and mineral composition. This paper selects the sedimentary structure to divide the shale facies. In the shale sedimentary structure, the striate layer is most easily identified and classified. So this paper selects Wuxi 1 well from the eastern margin of the Sichuan basin and the coke stone. The X and Y wells in the dam area and the five peak of the 3 section of the surface section of the Xiushan dissolve Creek section are observed and analyzed by microscope, and the 3 major shale facies, such as massive shale, parallel laminar shale, and non parallel shales, have been observed, as well as the porphyritic shale, transparent and granular shale and grain sequence shale. Too extensive shale facies. Under thin slices, the lamina of the massive shale is the least obvious, the lamina of the parallel shales is slender and straight, the layers of the non parallel shales are strong and intersected with each other. The main minerals in the striate are quartz, muscovite, feldspar, calcite, dolomite, and other brittle minerals, and clay in the surrounding matrix. The mineral composition of the 3 major shale facies in the five peak - Long Ma Creek formation shale is distinctly different in the mineral composition. The average quartz content, in order of massive shale, parallel layer shale and non parallel shales, decreased in turn, 61%, 50%, 32% respectively, and the average clay mineral content increased by 25.8%, 29.1%, and 53.2%. quartz content in turn. There is a positive correlation with TOC, and the clay mineral content is negatively correlated with the TOC. As for the mineral components, the shale gas reservoir properties of the massive shale and the parallel shales are superior to those of the non parallel shales. The fine characteristics of the layers can be observed by the scanning electron microscope, and the directional arrangement of the minerals is particularly obvious. The five peaks of the eastern margin of the Sichuan basin and the shale of the long Ma Xi formation are mainly in the shale. There are 8 kinds of micropores in the granular pore, clay interslice hole, grain margin hole, intergranular pore of raspberry globular pyrite, inner pore of clay particle, karst hole, organic pore and micro fissure. Although the difference of the diagenesis of different shale facies in the five peaks of the long Ma Creek shale is not too big and the evolution degree is similar. There are some differences in the distribution characteristics of their micropores. The intergranular pores in the granular shale are the most developed in the organic pore and the raspberry spheroidal pyrite in the bulk shale, while the grain intergrate holes and the clay interlamellar pores in the non parallel laminar shale are dominant. As for the organic matter, the organic matter of the 3 main types of main shale facies belongs mainly to the humic type. (I) the content of humic and humic mud type (II1).TOC is higher than that of parallel shales higher than that of non parallel shales. All samples of three sections show that massive shale TOC is 3.7%, parallel layer shale is TOC 3.4%, and the non parallel layer TOC is only the main trace data of the five peak of the eastern margin of the Sichuan basin, the east margin of the long Ma Creek formation shale. The brittleness of the 3 main types of shale facies is positively correlated with the TOC. The trace data shows that the water environment of the massive shale and the parallel shales is mainly from oxygen to oxygen poor, while the water environment in the non parallel shales is mainly poor oxygen to oxidation. The hydrodynamic environment reflected by the non parallel shales is stronger than the massive shale and parallel. The paleo salinity of the.3 major lithofacies reflected in the shales is micro brackish water, but the ancient water depth represented by the massive shale and the parallel shales is obviously larger than that of the non parallel shales. The massive shale represents a stable sedimentary environment, and the deposition rate can be quickly slow and can be formed in underwater canyons or on the shelf of the continental shelf. The region with high deposition rate can also be formed in areas with relatively quiet water body, low deposition rate, and sedimentation in the area of suspension. The key is that there is no obvious depositional discontinuity. The occurrence of the striate in the shale represents a environment associated with the periodic flood of rivers (intermittent suspended sediments), and the parallel shale is represented. This seasonal (or periodic) flood is not very violent, which makes the boundary between the sedimentary layers and the non deluge sedimentary layers clear and the erosion is lighter. The roughness of the grain layers of the non parallel laminar shale may reflect a more intense periodic flood. The sediment brought by the flood is obviously underflow. The difference in the main facies distribution reflected by three cross sections / wells in the transverse direction may be related to the position of the section in the shelf. Because of the high TOC, quartz content and a large number of developed organic pores, the significance of the massive shale and parallel shales is obviously greater than that of the non parallel lines. Layer shale.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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