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1.
The kaolinite rocks are very abundant in China coal mea-sures,most of which are very pure,excellent and in goodquality for industrial use.The geological feature,occurrence,origin and processing techniques are largely different fromthose of the traditional kaolins.The kaolinite rocks in Chinacoal measures are marvelous,but a large-scale kaolinite de-posit is rare in the world.The origin of kaolinite rocks in thecoal measures is under debate for a long time(Liu and Zhang,1 997;Liang,1 995;Boho…  相似文献   

2.
目前关于自生粘土矿物对深层孔隙结构及油气运聚的影响方面的研究十分薄弱.综合利用铸体薄片、全岩XRD、扫描电镜、恒速压汞等测试手段,分析自生粘土矿物对孔隙连通性、孔喉直径及其分布的影响,并结合埋藏史和生烃史探讨了低渗透砂岩不同孔隙结构类型的油气差异富集条件.珠海组深部储层压实作用较强,自生粘土矿物含量较高.碎屑颗粒以线接触-凹凸接触为主,识别出"孔隙+粗喉道"和"喉道主控"2种孔隙结构类型,前者孔隙体积和粗喉道占比较高,后者主要以细喉道为主;自生粘土矿物分割占据大量孔喉空间,自生伊利石主要为孔喉充填型,自生绿泥石主要为颗粒包壳型;珠海组储层与下渐新统恩平组烃源岩不整合接触形成纵向"下生上储"、横向连续分布的有利源储组合,烃源岩持续生烃.珠海组是典型的深埋藏碎屑岩低渗储层,仍具备良好的储集条件,储层发育受机械压实作用和自生粘土矿物共同控制;压实作用是原生孔隙损失的初始因素,以绿泥石和伊利石为代表的自生粘土矿物高度发育是制约优质储层发育的关键因素.   相似文献   

3.
This paper reports the results of our recent studies and generalizes previously known data on the geology, mineralogy, geochemistry, and genesis of the Russia’s largest Latnenskoe refractory clay deposit. It is shown that conditions of its localization were defined by regional and local factors. The regional factors controlled the distribution of the clay raw material in the region, while the local factors were responsible for the genesis and composition of refractory clays of the Latnenskoe deposit. Our studies showed that the formation of refractory clays is not only related to terrigenous but also to authigenic processes of sedimentation. The terrigenous component of clays was formed by the erosion of kaolin weathering crusts of the Voronezh anteclise crystalline basement and Paleozoic sedimentary hydromica–kaolinite rocks. Authigenic processes were significantly contributed by organic matter, which determined the environmental pH and Eh parameters. It is established that the mineral matter of clays of the deposit is represented by three morphological modifications (crystalline, amorphous, and biomorphic), which were formed subsequently and (or) simultaneously and could be transformed into each other. Application of a complex of modern precision methods allowed us to reveal a previously unknown biomorphic modification of kaolinite, the major rock-forming mineral, as well as mixed-layer kaolinite-smectite in the clays. It is shown that the distribution of major and trace elements and the sulfur isotope composition in different technological types of clay depend mainly on the facies conditions of their formation. Technological properties of clay raw material are considered.  相似文献   

4.
自生矿物特征和成因机理对深层碎屑岩储层物性具有重要影响。以渤海海域歧南断阶带侏罗系为例,通过岩心、薄片、扫描电镜、电子探针、同位素、包裹体、X衍射分析等技术手段,对研究区侏罗系深层碎屑岩储层自生矿物的类型、特征、成因机理及对优质储层发育的控制作用进行研究。结果表明:研究区侏罗系碎屑岩属于中孔-低渗储层,非均质性强;主要自生矿物类型为硅质矿物、碳酸盐矿物、黏土矿物3类;早期形成的硅质石英衬垫和碳酸盐胶结物控制了孔隙的发育和演化,沿颗粒表面分布的早期硅质石英衬垫有效抑制了后期石英加大生长,并增强了岩石的抗压能力,有利于原生孔隙保存;早期碳酸盐胶结物增强了储层抗压实能力,并为后期储层遭受溶蚀形成溶蚀孔提供了物质基础,有利于高孔隙储层形成;黏土矿物控制了储层渗透率差异,储层渗透率与自生高岭石体积分数呈正相关性,较高渗透率储层分布于侏罗系中段高岭石富集带内。研究区侏罗系碎屑岩发育原生孔隙体积分数高、微晶石英衬垫发育的Ⅰ类有利储层和粒间溶蚀孔隙较发育、具显著表生成岩作用特点的Ⅱ类有利储层,二者孔隙演化存在明显差异。Ⅰ类有利储层主要受早—中成岩期微晶石英衬垫抗压实作用控制,浅层和深层均可发育高孔隙储层;Ⅱ类有利储层主要受表生期风化淋滤作用控制,可在风化壳附近形成优质储层,整体上Ⅰ类储层物性优于Ⅱ类。  相似文献   

5.
Petrographic studies undertaken on samples from outcrops of the Jurassic Pilliga Sandstone intake beds in the extreme southeastern portion of the Great Australian Basin reveal an abundance of low birefringent clay material filling pore spaces and detrital grain fractures. Thin-section petrography and scanning electron microscopy indicate that much of this material is authigenic and X-ray diffraction studies show it to be essentially monomineralic, consisting of well-ordered kaolinite. Although the Pilliga Sandstone is quartz-rich, micrometric analysis indicates that potassium feldspar is present in quantities up to 20% of the total detrital material. Sporadic biotite mica is also present, constituting up to 3% of the detrital volume.Mechanisms for the formation of authigenic kaolinite are discussed in terms of chemical equilibrium and detrital mineral stability in aqueous systems. Chemical data from bore water and surface waters from this stratigraphic unit indicate that kaolinite is the major stable mineral phase in contact with these natural waters and that minerals such as potassium feldspar or mica would chemically alter to kaolinite. Such alteration of detrital mineral grains is supported by thin-section petrography and this mechanism is considered to be the source for the majority of the authigenic kaolinite observed.The hydrogeological characteristics of the Pilliga Sandstone intake beds are related to the extent of development of authigenic kaolinite.  相似文献   

6.
成岩作用对砂岩储层孔隙结构的影响   总被引:8,自引:3,他引:8  
砂岩储油物性的优劣不仅和沉积作用有关,而且和成岩作用有密切关系二本区延,砂层组中一些特珠孔隙结构和流体运动特征,及储油物性的变化,并不是沉积期形成的,而是成岩改造的产物。研究工作表明:成岩作用不仅改造了砂岩储层的孔隙结构和储油物性,而且在构成油藏圈团条件和油藏边界区的低渗透带等方面起了重要作用。  相似文献   

7.
Illite, illite-montmorillonite (I-M) mixed layer, kaolinite and chlorite are the principal clay minerals identified in the carbonate and terrigenous carboniferous rocks in the South Wales coalfield. Mineralogic changes and illite crystallinity are the main modifications in the studied rocks. Progressive illitization of I-M mixed layers (decrease in their expandabilities) towards the western part of the coalfield (i.e. in the direction of increase in coal-rank and grade of metamorphism), and the development of vermicular kaolinite, dickite, allevardite and pyrophyllite in the anthracite area are the main mineralogic changes. Illite crystallinity was determined by Weaver's sharpness ratio (S.R.) and isosharpness ratio maps of illite in the carbonate and terrigenous rocks are produced showing a gradual increase in illite crystallinity towards the west. Illites in the terrigenous rocks tend to be aluminous (evidenced by the increase in their intensity ratios, ‘I.R.’) with increase in coal-rank and grade of metamorphism towards the west. These changes are controlled to some extent by lithology. Correlation of illite S.R. with either its I.R. or expandability of I-M mixed layer, has outlined two diagenetic zones in the coalfield: zone I, the Diagenetic zone, in the eastern and southern regions; and zone II, the Metadi-agenetic zone, covering the central and northern parts of the central region. The Anchimetamorphic zone (zone III), which corresponds to the anthracite area in the northwestern region, was differentiated by correlating the illite S.R. with coal-rank. The occurrence of the above mentioned diagenetic zones and modifications of the clay minerals in the carboniferous rocks of the South Wales coalfield are mainly lateral without variation with increase in depth.  相似文献   

8.
台地泥质组分沉积记录了源—汇过程和环境演化等沉积学领域信息,可作为古气候和古环境重建的重要载体。然而,利用沉积物中的泥质组分进行古气候和古环境恢复时仍存在相当大的复杂性和局限性。鉴于此,笔者以上寺剖面中二叠统茅口组为例,通过研究该层位富泥质组分灰岩—泥灰岩韵律的宏微观形貌学和矿物学特征,发现其泥质组分主要由成岩黏土矿物海泡石构成,其次为少量滑石和蒙脱石。基于前人认识,进一步运用电子探针和激光原位元素地球化学分析手段,综合认为海泡石中镁元素来源于继承海水的孔隙水以及亚稳定矿物的转化释放,硅元素可能来源于上扬子台地的同沉积期断裂热液。此外,滑石主要形成于海泡石埋藏过程中的成岩转化,蒙脱石可能也具有类似成因,但不排除有少量蒙脱石来源于火山物质的海底改造。结合区域资料,华南中二叠统浅水碳酸盐台地上广泛发育自生成因(早期成岩作用和埋藏成岩作用)泥质组分。因此,在利用泥质组分来恢复古环境的时候,需要谨慎识别其成因,这将有利于提高沉积旋回识别和环境解释的准确性;另一方面,对自生成因泥质组分进行专门研究,在成岩过程以及成岩地球化学信号识别上也具有参考价值。  相似文献   

9.
Low Sr and Ca contents in fine-grained terrigenous rocks of the Vendian sedimentary cover in the East European Platform may be related to the following reasons: (1) the absence of authigenic carbonates in Vendian mudstones owing to desalination of epiplatformal sedimentary basins; (2) significant contribution of the chemically weathered rocks in the formation of the Vendian cover of the East European Platform.  相似文献   

10.
鄂尔多斯盆地姬塬地区延长组长4+5低渗透储层成因   总被引:3,自引:0,他引:3       下载免费PDF全文
碎屑岩储层成岩作用复杂而强烈,对储层物性有着重要影响。应用岩相学研究方法,在对鄂尔多斯盆地姬塬地区延长组长4+5低渗砂岩储层成岩作用及其对物性影响定量研究基础上,探讨了低渗储层成因机理。成岩作用和孔隙演化研究表明,压实作用虽然造成12%~20%的孔隙度损失,但是压实后剩余孔隙度仍高达15%~23%,早期胶结作用使孔隙度损失很小,压实作用和早期胶结作用并没有使储层致密,不影响油气渗流。溶蚀作用进一步改善了储层,晚成岩阶段A期-B期形成的钠长石、亮晶方解石、白云石、自生高龄石和铁绿泥石等大量胶结物的晚期胶结作用使储层孔隙度仅有4%~6%,储层因此而致密,由此影响油气渗流。晚期裂隙作用对储层孔隙度贡献为6%~8%,改善了储层物性而使其成为有效储层。盆地演化及与之对应的成岩事件研究认为,印支运动前,姬塬地区长4+5储层处于浅埋藏阶段,经历压实作用和早期胶结作用,早-中侏罗世长 7烃源岩进入未成熟-低熟阶段,形成富含有机酸流体进入储层而发生溶蚀作用,早白垩世中-晚期进入深埋藏成岩阶段,晚期胶结物大量形成而使储层致密。生烃增压作用导致的裂隙以及晚白垩世以来的构造运动形成的裂缝对研究区长4+5有效储层形成具有非常重要意义,同时对低渗油气藏勘探也具有指导意义。  相似文献   

11.
In the geochemical study of sedimentation, hydrogen and oxygen isotope data are useful for a discussionon formation conditions and material sources of sediments. Hydrogen and oxygen isotope analyses were madeon clays separated from the sea-floor surface sediments at 9 stations in the western sea region of the AntarcticPeninsula. On the basis of these isotopic data and the clay mineral components and by use of statistical dia-grams, it may be concluded that the clay fraction in this sea region is composed mainly of terrigenous detritus:i.e. it was formed by surface weathering or supergene alteration of the rocks from the terrigenous region in thepeninsular in the presence of meteoric water. However, at least a part of montmorillonite is a marine authigenicmineral formed by alteration of submarine eruptive materials or terrigenous pyroclasts in the presence of seawater. The above result is consistent with the idea derived from the study of clay mineralogy.  相似文献   

12.
对酒东盆地红山地区下白垩统含铀目的层中黏土矿物进行扫描电镜(SEM)、X射线衍射(XRD)、X射线能谱(EDX)等的系统研究,结果表明:含铀目的层碎屑岩的源岩主要是碱交代的酸性岩浆岩,其黏土矿物类型主要为高岭石,其次为绿泥石。高岭石既有陆源高岭石,也有自生(蚀变)高岭石;高岭石化带(浅色带)可以作为该区铀矿找矿的主要标志层,其厚度和蚀变强度等可以作为判断该区铀矿富集程度的依据之一。绿泥石主要为自生绿泥石,与高岭石形成于不同时期,可能是由高岭石转化而成。黏土矿物研究显示,该区自白垩纪以来经历了由温暖潮湿气候逐渐向干旱气候转变的过程。  相似文献   

13.
山东胜利油田第三系碎屑岩的埋藏成岩作用与储层评价   总被引:2,自引:0,他引:2  
研究区在新生代为一持续下沉的断陷盆地,碎屑岩十分发育.有些埋藏成岩矿物,其出现深度的温度,等于或接近于其他学者对这些矿物的实测温度.这类成岩矿物包括石英(次生加大)、自生高岭石、自生石榴石、腐蚀状绿帘石及粘土矿物等.根据与温度有关的各种成岩作用,可划分出浅成、中成、深成和超深成四个岩带.业已查明,埋藏成岩带可用以划分和评价碎屑岩储油层.  相似文献   

14.
Ip  Sabrina C. Y.  Choo  Jinhyun  Borja  Ronaldo I. 《Acta Geotechnica》2021,16(11):3381-3400

Geomaterials such as soils and rocks can exhibit inherent anisotropy due to the preferred orientation of mineral grains and/or cracks. They can also be partially saturated with multiple types of fluids occupying the pore space. The anisotropic and unsaturated behaviors of geomaterials can be highly interdependent. Experimental studies have shown that the elastic parameters of rocks evolve with saturation. The effect of saturation has also been shown to differ between directions in transversely isotropic clay rock. This gives rise to saturation-dependent stiffness anisotropy. Similarly, permeability anisotropy can also be saturation-dependent. In this study, constitutive equations accommodating saturation-dependent stiffness and hydraulic anisotropy are presented. A linear function is used to describe the relationship between the elastic parameters and saturation, while the relative permeability–saturation relationship is characterized with a log-linear function. These equations are implemented into a hydromechanical framework to investigate the effects of saturation-dependent properties on the shrinkage behavior of clay rocks. Numerical simulations are presented to demonstrate the role of saturation-dependent stiffness and hydraulic anisotropy in shrinkage behavior. The results highlight that strain anisotropy and time evolution of pore pressures are substantially influenced by saturation-dependent stiffness and hydraulic anisotropy.

  相似文献   

15.
Ridge sandstone of Jurassic Jumara dome of Kachchh was studied in an attempt to quantify the effects of diagenetic process such as compaction, cementation and dissolution on reservoir properties. The average framework composition of Ridge sandstone is Q80F17L3, medium-to coarse grained and subarkose to arkose. Syndepositional silty to clayey matrix (3% average) is also observed that occurs as pore filling. The diagenetic processes include compaction, cementation and precipitation of authigenic cements, dissolution of unstable grains and grain replacement and development of secondary porosity. The major cause of intense reduction in primary porosity of Ridge sandstone is early cementation which include silica, carbonate, iron, kaolinite, illite, smectite, mixed layer illite-smectite and chlorite, which prevents mechanical compaction. The plots of COPL versus CEPL and IGV versus total cement suggest the loss of primary porosity in Ridge sandstone is due to cementation. Cements mainly iron and carbonate occurs in intergranular pores of detrital grains and destroys porosity. The clay mineral occurs as pore filling and pore lining and deteriorates the porosity and permeability of the Ridge sandstone. The reservoir quality of the studied sandstone is reduced by clay minerals (kaolinite, illite, smectite, mixed layer illitesmectite, chlorite), carbonate, iron and silica cementation but on the other hand, it is increased by alteration and dissolution of the unstable grain, in addition to partial dissolution of carbonate cements. The potential of the studied sandstone to serve as a reservoir is strongly related to sandstone diagenesis.  相似文献   

16.
Postsedimentation alteration and structural assemblies of the Triassic sedimentary complexes of West Chukotka are discussed. Zoning of the alteration is based on examination of newly formed structural and mineral assemblages, the chemical composition, and the polytypes of clay minerals. Three zones of postsedimentation transformation of sandstones are distinguished: (1) the zone of chlorite, illite, and mixed-layer disordered chlorite-smectite; (2) the zone of illite and chlorite; and (3) the zone of phengite and ferroan chlorite. The grade of postsedimentation transformation and the composition of the newly formed micas are correlated with the cleavage type. The development of two-three types of cleavage leads to the highest degree of rock transformation. The assemblages of clay minerals and the crystal chemistry of the authigenic phengite show that the grade of postsedimentation transformation of the Triassic rocks attains the stage of greenschistfacies metamorphism in the zone of development of two cleavage types. Where the second cleavage is not documented or poorly developed, the rocks remain unmetamorphosed. Evidence is given that postsedimentation transformation of terrigenous rocks in the foldbelt is controlled largely by deformation.  相似文献   

17.
以松辽盆地南部团山子采石场辉绿岩侵入露头为例,采用连续密集取样、常规分析和碳氧稳定同位素测试等方法,对围岩储层的成岩及其变质特征进行分析,进而探讨岩浆侵入对围岩的影响及其储层意义。岩浆侵入对角岩围岩的影响包括:1)自生绢云母距离侵入体越远,其含量越少;2)粘土矿物主要为成岩晚期的伊利石和绿泥石;3)角岩中发育特殊“气孔-杏仁”构造。岩浆侵入对上覆砂岩的影响表现为:1)造成自生石英的特征分布;2)造成粘土矿物的不均匀分布;3)形成反映应力挤压特征的颗粒结构。角岩中浊沸石发育和高岭石不发育对应碱性环境,不利于热液微裂缝中碳酸盐矿物的溶蚀。因此,尽管角岩发育微孔、微缝等少量储集空间(平均孔隙度为1.70%),但其渗透能力很低(平均渗透率小于0.1 mD)。侵入活动对研究露头砂岩储层物性造成的不利影响,主要是由于挤压作用和热液流动作用使自生矿物不均匀分布,从而导致或加剧了砂岩储层的非均质性。  相似文献   

18.
Effective stress is one of the most important parameters which strongly affects pore volume compressibility curve, which is used in assessing the reservoir rock properties. It causes change in porosity as well as permeability of the reservoir rocks. In the present study, pore volume compressibility characteristics of the reservoir rocks at different effective stresses were used to derive the relationship of porosity and permeability with the effective stress. To this end, analytical processes for deriving the porosity–stress and permeability–stress relationships are discussed in relation to the reservoir rocks. As a result, a porosity–stress formulation is proposed which is in good agreement with the experimental data. Also, two formulas are proposed for permeability–stress relationship; one on the base of Kozeny–Carman permeability–porosity model and the other one is based on a differential form of permeability–porosity relationship. After calibrating the required coefficients for one sandstone and three limestones, it was concluded that the first permeability–stress model is the upper bound correlation while the latter is the lower bound. Furthermore, it is shown that the latter has better agreement to the real experimental data of the sansdstone samples, while the first one is close to the experimental observations from limestone samples. Also, it is concluded that structure of pores is a key factor on permeability–stress relationship, so that there is a significant difference between the experimental data and the proposed relationship for a limestone sample with vuggy pore spaces.  相似文献   

19.
彭晓蕾  刘立  计桂霞 《世界地质》2003,22(4):326-330,403
砂宝斯矿区的成矿围岩为长石石英砂岩,砂岩被多期次的石英脉、方解石脉和高岭石脉所穿切,这些多矿物脉是热液流体运移的结果。矿物脉形成过程中对围岩进行了热改造,使砂岩发生了压溶作用、胶结作用和溶蚀作用,形成了蚀变砂岩。由于流体酸碱性和温压的变化,孔隙水介质的性质由酸性向碱性转变,在酸性成岩环境下形成的蚀变高岭石、伊利石将转变成绿泥石、绢云母等。绢云母的大量出现,石英次生加大和自生粘土矿物的形成均是热液流体活动的产物。  相似文献   

20.
南翼山构造地表狮子沟组发育混积岩,作为一种特殊类型的沉积岩,其研究具有一定的实际意义和科学价值。本文在野外观察和镜下鉴定的基础上,对南翼山混积岩样品进行了X衍射、主微量元素及碳氧同位素测试,分析了混积岩的岩石学特征,考虑到其成分和成因的复杂性,通过数据分析排除了多种干扰因素,最后利用有效指标综合判断了其沉积环境。结果显示:南翼山构造地表混积岩中陆源碎屑平均含量为58.7%,碳酸盐矿物含量为31.0%,属于碳酸盐质陆源碎屑岩,主要为钙质泥岩,其中碎屑矿物以细粉砂级石英为主,碳酸盐矿物主要为泥晶方解石,黏土矿物组合为伊利石和有序伊蒙混层,且三者呈均匀混合的特征。数据分析表明Ca、Na、Mn、Sr、Ba等元素主要来源于自生矿物,稀土元素及碳氧同位素组成未受成岩作用影响,可以作为判断沉积时水体盐度和氧化还原条件的指标。根据Sr/Cu比值和K2 O/Al 2O3比值,结合黏土矿物组合及伊利石结晶度和化学指数,判断地表混积岩沉积时为寒冷干旱的气候条件;Sr/Ba比值和Z值表明古水体介质为咸水环境;U/Th比值、自生U含量和Ce轻微负异常等指标综合判定其形成于弱氧化环境。以上研究表明,南翼山构造地表混积岩主要为陆源碎屑和碳酸盐矿物均匀混合的钙质泥岩,形成于寒冷干旱气候条件下的弱氧化咸水湖泊环境中。  相似文献   

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