利用微观水驱油模型实验对储层进行流动单元的划分

采用微观水驱油模型实验测得西峰油田庄19井区长82储层26块样品的渗透率、水驱前含油饱和度以及在不同注入倍数、不同注入压力下的剩余油饱和度和驱油效率,以此参数为基础,应用统计分析软件SPSS将样品划分为E类、G类和M类3类流动单元。结合试验动态观察和数据分析,不同流动单元类型有着不同的渗流通道、驱替方式、驱油效率以及压力对驱油效率的作用。     

Identifying the Representative Elementary Volume for Permeability in Heterolithic Deposits Using Numerical Rock Models

Using a range of realistic 3D numerical lithofacies (dm-scale) models of ripple laminated sandstone intercalated with mudstone we evaluate how single-phase permeability varies as a function of sample support. The models represent a range of mudstone content which is typical for tidal deposits. Furthermore, the spatial distribution of flow barriers (i.e. mudstone) is not random, but governed by sedimentological rules giving a variable anisotropy ratio as a function of mudstone content. Both vertical and horizontal permeability are found to vary at small sample volumes, but these fluctuations reduce as the sample volume increases. The vertical permeability increases while the horizontal permeability is nearly constant as a function of sample support for small mudstone contents. For higher mudstone content, the horizontal permeability decreases while the vertical permeability is nearly constant as a function of sample support. We propose a criterion, based on a normalised standard deviation, to determine the Representative Elementary Volume (REV). The size of the REV is dependent on both the property measured (vertical and horizontal permeability) and the correlation lengths of the lithological elements (i.e. lithofacies). Based on this we identify three flow upscaling regimes that each require a different method for upscaling: (1) layered systems where the arithmetic and harmonic averages are appropriate, (2) systems close to the percolation threshold where a percolation model should be used, and (3) discontinuous systems where an effective medium method provides the best estimate of permeability. The work gives, by using numerical experiments on a range of heterogeneous systems, a new insight in determination of the REV for permeability at the lithofacies scale and its relation to sedimentological parameters.     

渤海湾盆地车镇凹陷古近系构造样式对沉积及储集层的影响*

近年来,构造对沉积的控制作用研究成为当前国际地质和油气勘探研究中的一个热点,但构造对储集层质量影响的研究相对较缺乏。在对车镇凹陷构造、沉积、储集层研究的基础上,讨论了不同构造样式中沉积充填和储集层发育特征。构造样式对沉积充填类型及特征具有重要影响,其中板式构造样式区仅发育近岸水下扇及少量滑塌浊积扇;铲式构造样式区除在边界断裂根部附近发育近岸水下扇外,其前端湖底扇常较发育;断阶式和坡坪式构造样式区受次级断裂控制,陆上与水下沉积常常共生,沉积类型多样,从冲积扇、扇三角洲到近岸水下扇、湖底扇均可发育。构造样式通过影响砂砾岩体的垂向叠置方式、规模和沉积类型及砂体结构,最终影响了其储集层质量。综合研究认为,断阶式和坡坪式构造样式区沉积类型丰富,为有利储集层最发育区;铲式构造样式区湖底扇发育,砂砾岩单层薄,为次级有利区;而板式构造样式区砂砾岩展布窄、单层厚度大,储集层质量最差。该认识为中低勘探程度的含油气断陷盆地中优质储集层发育带的预测提供了思路。     

白庙气田沙三上亚段沉积环境与油气分布关系

白庙气田为一受兰聊断层控制的滚动逆牵引半背斜，是既受构造控制又受岩性影响的复合型圈闭。1980年发现白庙气田，且有沙二^下、沙三^上、沙三^中、沙三^下4套含油气层系，经过二十多年的勘探开发研究，气田的构造特征已基本查清。随着滚动开发工作的深入，由寻找构造圈闭转为寻找岩性地层圈闭将是今后地质研究工作发展的方向。白庙气田的勘探与试采情况表明沙三^上亚段是其主产层系。本文通过对白庙气田沙三^上亚段沉积环境的研究，重点讨论了沉积环境与砂体分布及储层特征的关系，进而指出油气聚集的有利相带。     

秦岭北麓晚二叠世平顶山段辫状河—辫状三角洲沉积体系及其构造涵义

秦岭北麓晚二叠世石千峰组下部的平顶山砂岩段不整合覆于早、中二叠世含煤地层之上,是一套板状交错层理十分发育并以粗碎屑长石砂岩和长石石英砂岩为主的地层,以辫状河道与辫状三角洲充填沉积占优势。平顶山砂岩段呈自南向北并向东、西两侧变薄的朵状体。平顶山砂岩以含大量的新鲜的钾长石和古水流方向自南指向北和北西为特征,明显区别于下伏含煤地层中的砂岩。石千峰组砂岩与下伏煤系砂岩的厚度、古水流方向和岩石矿物成分的截然变化,表明华北石炭、二叠纪克拉通盆地南部的陆表海至晚二叠世已经完全退出华北,盆地南缘出现了新的物源隆起区,古沉积斜坡由原来的向南倾斜转变为向北倾斜。这意味着秦岭—大别构造带与华北板块南缘在此时期已经开始发生了碰撞并隆起成山。平顶山砂岩为硅质胶结,孔渗条件很差,储集油气的希望不大。     

新疆三塘湖盆地盖层特征及层间氧化带砂岩型铀矿成矿远景分析

本文结合盆地的区域地质背景，分析了三塘湖盆地的盖层沉积构造特征、找矿目的层的空间展布、地下水“补－径－排”系统和层间氧化带发育特征，认为该盆地相对稳定，埋藏浅的斜坡带地段具备了层间氧化带砂岩型铀矿成矿环境，应进一步开展工作。     

沉积体系分析与河道砂岩型铀矿成矿条件讨论--以鄂尔多斯中新生代盆地东胜地区为例

本运用沉积体系理论，对东胜地区直罗组的沉积相及沉积体系归属进行系统分析，指出直罗组为河流相沉积，其河流演化经历了早期辫状河、中期低弯度曲流河和晚期高弯度曲流河3个阶段。根据气候演变特点将直罗组分为上、下两个岩性段：下段为温湿条件下的辫状河沉积和低弯度曲流河沉积，形成灰色沉积建造；上段为干旱炎热条件下的曲流河沉积，形成以红色为主的杂色沉积建造。本区铀矿化属河道砂岩型，矿化受辫状河道控制，主要赋存于辫状河沉积砂体中。同时，对河道砂岩型铀矿化的成矿条件进行了初步探讨。     

综合物探方法在巴彦毛都盆地寻找砂岩型铀矿的应用

通过在巴彦毛都盆地开展磁法、电阻率测深、自然电场法、^210Po等综合物探方法，基本查明了该盆地基底形态与埋深、盖层结构与找矿目的层发育特征、深部层间氧化带发育情况及铀矿化信息，为该盆地砂岩型铀矿远景评价提供了依据。     

兰坪中新生代盆地沉积岩源区构造背景和物源属性研究--砂岩地球化学证据

沉积盆地中砂岩的地球化学成分主要受物源区控制。因此，通过分析砂岩的化学成分可以揭示盆地沉积岩的源区构造背景和物源属性。对兰坪盆地中新生界砂岩的常量成分、稀土和微量元素进行的分析，揭示盆地沉积岩的源区构造背景属被动大陆边缘和大陆岛弧，结合岩相古地理资料认为在中生代以前，盆地东侧可能主要处于被动大陆边缘环境。而西侧则可能以大陆岛弧环境为主，这与区域地质资料相吻合。沉积物源岩的原始物质应来自上地壳，以长英质岩石为主，并有少量安山质岩石和古老沉积物的混入，故兰坪中新生代盆地属典型的大陆型盆地。从而为正确认识古特提斯洋的演化和盆山转换过程提供了强有力的地球化学证据。     

Kaolinitic meniscus bridges as an indicator of early diagenesis in Nubian sandstones, Sinai, Egypt

Characteristic meniscus geometries formed by kaolinitic infiltration are observed in Nubian sandstones collected on the western coast of the Sinai Peninsula (Egypt). Based on petrographic and scanning electron microscope (SEM) observations, the kaolinite forming the menisci consists of mixed-size discrete platelets that gather into the corners around the framework grain-to-grain contacts. Specifically, the internal fabric of menisci indicates a general organizing trend from (1) the centre, where the platelets coat the framework grains; (2) to the peripheral zone, where they are oriented tangentially to grain surfaces; (3) to the pore linings with curvatures that are consistent with theoretical considerations of air–water interfaces. This typical arrangement suggests a detrital origin of kaolinite platelets by mechanical infiltration into sediments lying above the tablewater, in vadose conditions. This type of clay cementation occurring during early diagenesis can prevent (delay) deep burial diagenetic processes and therefore preserve excellent reservoir properties.