合川地区须二段储层致密化机理研究

发布时间：2018-02-27 02:37

本文关键词： 致密储层成岩作用成岩环境致密化机理合川地区须二段　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：四川盆地中部合川地区须二段发育典型的低孔渗致密砂岩储层,论文依据沉积岩石学、石油地质学、储层地质学、油气地化等理论,结合岩心实物观察、镜下岩石薄片鉴定、压汞、扫描电镜、电子探针、流体包裹体、X衍射、阴极发光等实验技术,对合川须二段储集层基本的岩石学特征、成岩作用特征、储层成岩演化等进行了深入的研究,并初步探讨了该区储层的致密化机理。通过研究后认为合川地区须二段主要为滨浅湖亚相滩坝砂体,砂岩成分成熟度与结构成熟度均较高,杂基含量较低(一般小于5%),颗粒分选好、次圆-圆状为主。岩屑类型多样,包括变质岩屑、沉积岩屑和岩浆岩屑,但主要以变质岩屑为主,反映了研究区须二段受多物源体系影响,主要岩石类型为细-中粒岩屑长石砂岩和细-中长石岩屑砂岩。储层孔隙度分布在0%～14%,平均5.98%,主要集中在4%～6%区间内,渗透率主要集中在O.O1mD～0.1mD,为典型的低孔、超低渗—致密储层。孔隙类型以残余原生粒间孔为主,伴随着发育长石、岩屑等粒内溶孔。储层砂岩经历了复杂的成岩作用,现处于中成岩B亚期。据薄片观察、微量元素测定以及研究区孔隙演化史等研究表明,储层孔隙度在晚侏罗世末降低至10%以下,已基本致密化,后期溶蚀作用对储层孔隙性有一定的改善,但受第二期硅质胶结作用及晚期铁方解石胶结作用等影响,储层孔隙性再次变差,自生伊利石等胶结物更是严重阻塞孔隙喉道,大量降低储层渗透率,使得研究区须二段最终演化为现今的低孔、超低渗—致密储层。分析认为沉积作用从宏观上控制着研究区碎屑颗粒的成分、粒度、含量以及储层的空间展布等,是影响储层物性的基础因素,而成岩作用是储层致密的最终原因:压实、硅质胶结及局部的钙质胶结作用大量减孔,自生伊利石等黏土矿物严重阻塞孔隙喉道,最终导致储层致密化。
[Abstract]:Typical tight sandstone reservoirs with low porosity and permeability are developed in the second member of Xujie area in the central part of Sichuan Basin. According to the theories of sedimentary petrology, petroleum geology, reservoir geology, oil and gas geochemistry, and combined with the observation of rock core, the thin sections of rock are identified under microscope. Mercury injection, scanning electron microscope, electron probe, fluid inclusion X-ray diffraction, cathodoluminescence and other experimental techniques have been used to study the basic petrological characteristics, diagenesis characteristics and diagenetic evolution of the reservoir in the second member of Hechuan formation. The mechanism of reservoir densification in this area is preliminarily discussed. It is considered that the second member of Xuzhou formation in Hechuan area is mainly a shore-shallow lacustrine subfacies beach bar sand body, and the composition maturity and structure maturity of sandstone are both relatively high. The content of complex base is relatively low (generally less than 5%), the particles are sorted well, the subround and round shape is dominant. There are various types of cuttings, including metamorphic, sedimentary and magmatic, but mainly metamorphic. The results show that the Xuer member in the study area is affected by multi-source system, and the main rock types are fine to medium grain lithic feldspar sandstone and fine to medium feldspathic sandstone. The porosity of reservoir is distributed in 0 ~ 14 and average 5.98, mainly in the range of 4% or 6%. The permeability is mainly concentrated in O.O1mD0. 1mD, which is a typical low porosity, ultra-low permeability tight reservoir. The pore type is mainly residual primary intergranular pore, accompanied by the development of feldspar, lithic and other intragranular dissolved pores. The sandstone has experienced complex diagenesis. According to thin slice observation, trace element determination and pore evolution history of the study area, the porosity of the reservoir decreased to below 10% at the end of the late Jurassic, and the reservoir has been basically densified. The late dissolution improved the reservoir porosity to some extent, but affected by the second stage siliceous cementation and the late iron calcite cementation, the reservoir porosity became worse again, and the authigenic Illite cemented material seriously blocked the pore throat. The reservoir permeability is greatly reduced, which makes the second stage of the study area finally evolve into the present low-porosity, ultra-low-permeability and dense reservoir. It is considered that the sedimentary process controls the composition and particle size of the clastic particles in the study area macroscopically. Content and spatial distribution of reservoir are the basic factors affecting reservoir physical properties, and diagenesis is the ultimate cause of reservoir density: compaction, siliceous cementation and local calcareous cementation reduce pore mass, Authigenic Illite and other clay minerals seriously block pore throat, resulting in reservoir densification.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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