川中地区上三叠统须家河组绿泥石胶结相储层研究

发布时间：2018-03-03 15:34

本文选题：川中地区　切入点：须家河组　出处：《东华理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：绿泥石在各种岩石和地质环境中广泛存在,它既属于低级变质岩和热液蚀变岩中主要矿物,又常见于沉积岩中,在我国中新生代陆相含油气盆地的砂岩储层中分布广泛。一直以来,绿泥石的特征、组成、成因、对储层影响等方面逐渐受到地学界学者的关注。本文以四川盆地川中地区上三叠统须家河组储层砂岩中的自生绿泥石为研究对象,对自生绿泥石的总体赋存状态、形成演化机制、空间分布规律以及与孔隙度—渗透率之间的关系等进行详细探究,进一步探讨砂岩储层中的自生绿泥石在整体上对孔隙的保存和其他物理性质上的关系和影响。研究区储层属低孔—低渗级储层,类型上以孔隙型或裂缝孔隙型为主。川中地区上三叠统须家河组砂岩主要类型以岩屑石英砂岩为主,比例在半数以上。碎屑特征上以中等粒度砂级为主,分选性和磨圆度均为中等以上,杂基含量低,仅为5.4%左右。压实作用和胶结作用是影响研究区砂岩储集能力的重要因素,然而胶结物平均值仅为4.09%,且以粘土矿物胶结为主,对储层的影响较大,胶结作用和压实作用是本区储层物理性质变差的主要因素。自生绿泥石是研究区主要粘土矿物之一,其平均含量约为3.2%,在形态上多体现为孔隙衬里或颗粒的等厚环边,自生绿泥石的存在会使颗粒接触强度普遍较低,通常为点接触-线接触,在颗粒接触的缝隙绿泥石并不多见。绿泥石具有世代结构,沉淀后依然会继续生长,可见自生绿泥石对自生石英生长的限制甚至侵蚀。在骨架颗粒发生溶解时,绿泥石会在其边界形成包围形态,对该种次生孔隙起到保护作用。总之,绿泥石在砂岩孔隙中的环边衬里胶结作用是川中地区须家河组砂岩孔隙得以保存的重要机制,主要从以下两方面保存了深埋地层中的孔隙:物理性质上,绿泥石在孔隙中的胶结增加了岩石的机械强度和抗压实能力,使原生粒间孔隙和次生溶蚀孔隙等在地质过程中得以保存;化学性质上,由于晚期阶段由于绿泥石环边的存在,在一定程度上抑制了石英的次生加大作用,保护了孔隙空间。
[Abstract]:Chlorite is widely found in various rock and geological environments. It is not only a major mineral in low grade metamorphic rocks and hydrothermal alteration rocks, but also a common one in sedimentary rocks. It is widely distributed in sandstone reservoirs in Mesozoic and Cenozoic continental petroliferous basins in China. The influence on reservoir has gradually attracted the attention of geoscientists. In this paper, the authigenic chlorite in the reservoir sandstone of the Upper Triassic Xujiahe formation in Sichuan Basin is taken as the research object, and the overall occurrence state of the authigenic chlorite is studied. The mechanism of formation and evolution, the law of spatial distribution and the relationship between porosity and permeability are discussed in detail. Further discussing the relationship and influence of authigenic chlorite in sandstone reservoir on pore preservation and other physical properties as a whole. The reservoir in the study area belongs to low porosity and low permeability reservoir, The sandstones of the Upper Triassic Xujiahe formation in the central Sichuan area are dominated by lithic quartz sandstone with a proportion of more than half. The sorting and grinding roundness are both medium, and the heterogeneity content is only about 5.4%. Compaction and cementation are the important factors affecting the sandstone reservoir capacity in the study area. However, the average value of cementation is only 4.09, and the clay mineral cementation is the main factor. The cementation and compaction are the main factors for the deterioration of reservoir physical properties in this area, and authigenic chlorite is one of the main clay minerals in the study area. The average content of chlorite is about 3.2, which is usually reflected in the pore lining or the equal thick ring edge of particles in shape. The presence of authigenic chlorite will make the contact strength of particles generally lower, usually point contact line contact. There are few crevice chlorite in contact with particles. Chlorite has a generation structure, and it will continue to grow after precipitation. It can be seen that the growth of authigenic quartz is restricted or even eroded by authigenic chlorite. When the skeleton particle dissolves, The formation of surrounding morphology of chlorite at its boundary protects the secondary pores. In short, the cementation of chlorite in sandstone pores is an important mechanism for the preservation of sandstone pores in Xujiahe formation in central Sichuan. The pores in the deep buried strata are preserved mainly in the following two aspects: in terms of physical properties, the cementation of chlorite in the pores increases the mechanical strength and compaction resistance of the rocks. The primary intergranular pores and secondary dissolution pores are preserved in the geological process, and the chemical properties, due to the existence of chlorite ring edge in the late stage, to some extent inhibit the secondary enlargement of quartz and protect the pore space.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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