温西三块水淹层孔隙度、渗透率精细建模测井分析方法

温西三块注水开发20多年来,油层物理性质、参数大小及测井响应发生明显而复杂的变化,水淹层中注入水强烈冲刷,岩石孔隙度、渗透率均有不同程度变化,利用岩石物理相分类精细研究了其水淹层孔隙度、渗透率建模。通过油区测井、岩心和试油试采资料,分类建立的水淹层孔隙度、渗透率模型,其数据点均匀程度及其线性关系有明显集中分布趋势。特别是分类模型利用分类声波时差、中子孔隙度参数综合拟合值求取孔隙度;渗透率采用分类的多种测井响应综合评估确定,提高了水淹层孔隙度、渗透率参数计算精度,为准确计算水淹层孔隙度、渗透率提供了有效分析方法。     

注水开发中濮城油田储集层性质变化的研究

濮城油田主要产层已进入高含水及特高含水阶段。储集层在注入水的长期冲洗下,孔隙度大、渗透率高的地层,注水后孔隙度、渗透率都将增大;而岩性致密的储层,注水后孔隙度、渗透率基本保持不变或略有下降。随着水洗程度的增加,砂岩颗粒表面的粘土被水冲掉或冲散,颗粒表面光滑,岩石表面润湿性由亲油向亲水方向转化。长期受注入水的冲刷,相渗透率曲线表现出两相流跨度较小,水相渗透率急剧上升的特点。储集层在注水开发过程中,水     

唐家河油田三断块储集层参数四维模型的建立

根据不同开发阶段的钻井、测井、室内驱替实验及各项生产动态资料,建立了唐家河三断块储集层物性参数随注水开发过程而变化的四维动态演化模型。1971—1982 年孔隙度、渗透率年相对减小率分别是1.63％和2.58％;1982 年后孔隙度、渗透率年相对增大率分别是1.00％和5.57％. 分析引起储集层参数在开发不同时期变化的原因主要包括：油藏温度、压力的降低、流体性质的改变及注入水动力作用所引起的岩石性质和微观结构的变化。用所建立的四维储集层参数动态仿真模型预测了不同开发阶段流动单元内部油水运动特点及剩余油分布状况,结果表明,与同期相应油水井的生产状况基本吻合。     

靖安油田盘古梁长6油层组储层流动单元研究

储层流动单元划分对认识油藏的非均质性、注水开发效果和剩余油分布规律研究提供了有效手段。以靖安油田盘古梁长6油层组为例,选取了渗透率、孔隙度、储层质量指数、标准化孔隙度指数及流动带指数作为研究区流动单元划分的参数,将靖安油田盘古梁长6储层流动单元划分为A、B、C3类,划分结果与沉积微相、砂体展布、物性具有很好的对应关系,能够真实客观地反映低渗砂岩储层物性差、非均质性强的地质特征。     

基于流动单元的致密砂岩气储层渗透率测井评价——以川中广安地区须家河组为例

四川盆地广安地区须家河组致密砂岩气储层非均质性极强,使得孔隙度与渗透率相关性差,难以通过单一的孔隙度与渗透率回归模型准确计算渗透率。因此,利用859块标准柱塞样物性分析数据,根据流动单元指数(FZI)由小到大,划分出了5类流动单元,并建立了相应的孔隙度与渗透率统计回归模型,每种类型流动单元的孔隙度与渗透率相关性良好。为了使用这组分类统计模型,需要连续的FZI来划分整个目的层段的流动单元类型。为此,选择了20块典型样品开展高压压汞与核磁共振联测实验。基于联测实验数据,得到了利用核磁共振测井计算Swanson参数、利用Swanson参数计算储层品质因子(RQI)、利用RQI计算FZI的转换模型,实现了FZI的连续定量评价,最终实现了研究区致密砂岩气储层流动单元类型的连续划分及其渗透率的测井评价。现场应用结果表明:利用核磁共振测井计算FZI与岩心分析FZI较为接近,该方法可有效解决FZI连续定量评价的问题;相比于单一的孔隙度和渗透率回归模型与核磁Coates模型,流动单元分类的渗透率计算结果与岩心分析渗透率吻合度更高,该方法有效地提高了渗透率测井评价的准确度。上述方法在类似的致密砂岩气储层渗透率测井评价中具有推广价值。     

关于用FZI划分流动单元的探讨

FZI(流动分层指标)是与储集层孔隙度和育效水力半径育关的变量,用油藏品质指数与归一化孔隙度的比值定义．被广泛用于定量识别和划分流动单元。但FZI的定义本身存在一定问题,对其基本原理及推导过程进行的理论分析表明：即使在同一流动单元内,FZI是与孔隙度有关的变量,得不出确定的渗透率与孔隙度的相关关系：岩石的渗透率和孔隙度同时扩大或缩小合适的倍数会得到相同的FZI值,即物性差异很大的储集层可能FZI值相同。昕以用该指标划分的流动单元不符合“流动单元内部储集层物性差异最小、不同流动单元之间储集层物性差异最大”的要求．在流动单元的识别和划分中应慎用该方法。参13     

基于动态资料的低孔低渗砂岩储层渗透率测井评价方法——以陆丰凹陷古近系为例

复杂孔隙结构导致陆丰凹陷古近系低孔低渗砂岩储层的孔隙度级别相同，但渗透率相差1~2个数量级，常规孔渗模型计算渗透率的精度低，难以满足当前对古近系储层有效性识别和产能预测的需求。通过综合运用岩心物性分析、压汞和核磁共振T₂谱，将储层划分为4类流动单元，利用电缆地层测试流度结合孔隙度识别流动单元类型，实现储层绝对渗透率的准确评价。在此基础上，基于岩心相渗实验建立岩心尺度上的绝对渗透率和最大油相渗透率的转换模型，然后利用纯油层取样渗透率和钻杆测试（DST）试井解释渗透率建立岩心尺度到DST试井尺度的渗透率转换模型，最终实现DST测试油相渗透率的计算。运用电缆地层测试流度结合流动单元法对陆丰凹陷5口井古近系地层绝对渗透率进行评价的结果显示，预测渗透率的相对误差平均值为48.3%，精度明显高于Herron模型。采用测井计算的DST尺度油相渗透率对3口井的产能进行预测，结果与实际测试产能吻合较好。     

基于等效岩石组分理论的渗透率解释模型

以等效岩石组分理论为基础,依据电荷迁移与流体分子迁移相似性原理,在有效导电孔隙度的基础上,提出了有效流动孔隙度的概念并推导了其表达式,研究认为有效流动孔隙度与对数下的渗透率是一种线性关系。选取四川盆地须家河组29块具有代表性的低渗岩样,进行了岩心物性分析、电阻率及核磁共振实验测量,获取了29块岩样的孔隙度、渗透率、地层因素及束缚水饱和度实验数据。利用遗传算法,建立了渗透率与有效流动孔隙度之间的最优模型,将新建立的渗透率模型与Wyllie-Rose渗透率模型和Timur渗透率模型进行对比分析,认为新建立的渗透率模型效果优于其他2种模型,可以有效地应用于储层渗透率测井评价。     

黄骅坳陷羊三木油田河道砂储层动态模型表征

在油田注水开发过程中,储层性质会发生变化.以黄骅坳陷羊三木油田为例,通过岩心分析、对子井分析以及动态模型的建立,表征了注水开发前后储层性质的变化规律.羊三木油田主要发育河流相砂体,具有高孔、高渗透的特征,注水开发后储层不稳定矿物含量减少,粒度分选性变好,泥质含量明显减少,孔喉半径增大,孔隙度和渗透率普遍增大,渗透率最大可增加2～4倍.利用对子井注水开发后渗透率与注水开发前渗透率的单元回归分析发现,两者的对数值具有线性相关关系,得到的预测模型与实际模型符合率高达90%以上.     

基于格子玻尔兹曼方法的数字岩心孔隙流动模拟

基于格子玻尔兹曼方法的多孔介质流动模拟应用广泛,然而岩石孔隙流动的研究多数针对基于岩石切片数值重构的数字岩心,较少有真实岩心孔隙流动模拟。本文基于渤海S油田真实数字岩心开展孔隙流动模拟。利用灰度处理、图像二值化、边界跟踪等图像处理技术实现岩石孔隙网络建模,基于格子玻尔兹曼方法完成三维孔隙流动建模,实现数字岩心三维流动可视模拟,并依托模型计算开展储层孔隙度-渗透率统计分析。研究结果表明,模型计算孔隙度-渗透率关系与油田实际误差低于4.0%。     

丘陵油田西山窑组流动单元划分与注水效果分析

针对丘陵油田西山窑组储集层低孔特低渗的油藏特征,结合注水开发动态,选取反映储集层物性、沉积特征及流体性质的主要参数,对流动单元进行了划分,共划分出E、G、M、P 4种类型。研究表明,流动单元的平面展布在一定程度上受沉积微相控制,不同类型的流动单元其渗流能力和储集能力差异较大,在生产动态特征方面表现为吸水、产液及含水特征存在明显差异。因此,注水开发阶段以流动单元为基础进行动态分析和潜力研究,有助于获得较理想的开发效果。     

吐哈油田温五区块岩石相模型

在模拟储层非均质性时，由于大规模的连通性对流体运动有重大影响，因此重要的非均质性和大规模的结构应先模拟，然后模拟小尺度的非均质特征，这样可为得到更合理的地质模型提供保障。这种模拟过程通常就是我们所称的相控储层模拟。就温五区块岩石相与储层物性之间具有较好的相关性这一特点，结合工区地质特征、侧井曲线特征，在划分出四类岩石相的基础上，建立了各类岩石相的判别模型，并解释出了35口井的岩石相，然后利用MODRES模拟程序中的克里格模块建立了小层岩石相分布模型，分析了各类相带的分布特征。作为岩石相模型的进一步应用，还在岩石相这一储层结构模型的基础上，建立了更加精确的渗透率模型，并指出了有利的储集区。     

POROSITY AND PERMEABILITY EVOLUTION ACCOMPANYING HOT FLUID INJECTION INTO DIATOMITE

An experimental study of silica dissolution was performed to probe the evolution of permeability and porosity in siliceous diatomite during hot fluid injection such as water or steam flooding. Two competing mechanisms were identified. Silica solubility in water at elevated temperature causes rock dissolution thereby increasing permeability; however, the rock is mechanically weak leading to compression of the solid matrix during injection. Permeability and porosity can decrease at the onset of fluid flow. A laboratory flow apparatus was designed and built to examine these processes in diatomite core samples. At the core level, we measured the pressure drop as a function of time for fixed injection rates to determine permeability variation and utilized an X-ray Computerized Tomography (CT) scanner to measure in-situ porosity. At the pore level, a scanning electron microscope (SEM) was used to observe changes in pore morphology. We found that porosity decreased initially due to compaction caused by the imposed pressure drop across the core. Later, porosity increased as silica dissolved. Dissolution of the rock matrix appeared to be relatively uniform; wormholes were not observed even after tens of pore volumes of fluid injection.     

POROSITY AND PERMEABILITY EVOLUTION ACCOMPANYING HOT FLUID INJECTION INTO DIATOMITE

An experimental study of silica dissolution was performed to probe the evolution of permeability and porosity in siliceous diatomite during hot fluid injection such as water or steam flooding. Two competing mechanisms were identified. Silica solubility in water at elevated temperature causes rock dissolution thereby increasing permeability; however, the rock is mechanically weak leading to compression of the solid matrix during injection. Permeability and porosity can decrease at the onset of fluid flow. A laboratory flow apparatus was designed and built to examine these processes in diatomite core samples. At the core level, we measured the pressure drop as a function of time for fixed injection rates to determine permeability variation and utilized an X-ray Computerized Tomography (CT) scanner to measure in-situ porosity. At the pore level, a scanning electron microscope (SEM) was used to observe changes in pore morphology. We found that porosity decreased initially due to compaction caused by the imposed pressure drop across the core. Later, porosity increased as silica dissolved. Dissolution of the rock matrix appeared to be relatively uniform; wormholes were not observed even after tens of pore volumes of fluid injection.     

鄂尔多斯盆地马岭油田长81储层不同流动单元可动流体赋存特征及其影响因素

鄂尔多斯盆地马岭油田长8₁储层是典型的低孔—低渗透油藏,渗透率的强非均质性制约了油气储层品质的提高。通过开展核磁共振实验,结合恒速压汞和高压压汞、图像粒度、铸体薄片等微观实验研究储层的微观孔隙结构特征,同时选取砂厚、孔隙度、渗透率、含油饱和度、流动带指数5个参数,借助SPSS数据分析软件,将马岭油田长8₁段储层的流动单元划分为E、G、M、P等4类,进而分析不同类型流动单元微观孔隙结构特征及其对可动流体饱和度的影响,结合生产动态数据分析不同类型的流动单元产能的差异。结果表明:不同流动单元的微观孔隙结构有着明显的差异,是造成可动流体饱和度差异的主要因素。其中,喉道半径分布形态及主流喉道半径大小起了决定性作用。生产动态数据表明,在油气田勘探开发阶段E类和G类流动单元的产能最高,应根据不同流动单元的微观孔隙结构差异性特征,实施合理有效的开发方案。      

FLOW UNIT CLASSIFICATION FOR GEOLOGICAL MODELLING OF A HETEROGENEOUS CARBONATE RESERVOIR: CRETACEOUS SARVAK FORMATION, DEHLURAN FIELD, SW IRAN

Flow unit classifications can be used in reservoir characterization and modelling of heterogeneous carbonate reservoirs where there is uncertainty and variability in the distribution of porosity and permeability. A flow unit classification requires the integration of geological and petrophysical data, together with reservoir engineering and production data. In this study, cores and thin sections from the upper part of the Cretaceous Sarvak Formation at the Dehluran field, SW Iran, were studied to identify flow units which were then used in reservoir modelling. Eight flow units were defined based on a classification of depositional environments and diagenetic processes and an evaluation of porosity and permeability. In lagoonal deposits, two flow units were distinguished in terms of dissolution effects (i.e. low or high values of vuggy porosity). In shoal/reef deposits, three flow units were distinguished in terms of cementation volumes and grain frequency. In open‐marine deposits, two flow units were identified with different degrees of dissolution; while intrashelf basinal deposits were characterized by a single flow unit with no observable reservoir potential. Each flow unit was characterized by unique values of porosity, permeability, water saturation and pore throat distribution. Grain‐supported deposits from high energy depositional environments (shoals) had the highest porosities and permeabilities. However, these rocks were frequently cemented with a consequent reduction in porosity and permeability. By contrast, low permeability mud‐supported deposits had undergone dissolution, forming highly permeable flow units. Capillary pressure curves from mercury injection were used to determine the distribution of pore throat sizes and the pore characteristics of the flow units, and were used to give an indication of the productivity of each flow unit. Flow units were modelled using a pixel‐based modelling tool. Modelled reservoir characteristics were mainly controlled by facies changes in the vertical direction, and by diagenetic variations in the horizontal direction. Input values for the geometry of the flow units were based on information from geological and diagenetic models of the reservoir, and from thickness maps of the flow units derived from well data.     

低渗透油藏不同流动单元并联水驱油

为了描述低渗透油藏多层合注合采时,各层水驱效果差异、流体流动特征及分布规律,开展了不同流动单元并联水驱油实验及数值模拟研究。以新疆宝浪油田宝北区块低渗透储层为例,按流动层段指标由大到小将储层划分为五类流动单元,选取其中三类流动单元的9块天然岩心与1块人造岩心,组成4组并联模型,进行了水驱油实验及数值模拟研究。实验结果表明：不同流动单元岩心并联组合后,物性好的流动单元驱油效率比单独驱替时要高、物性差的流动单元驱油效率比单独驱替时要低;不同流动单元之间渗透率级差越大,流动单元之间相互影响越强烈,驱油效率相互差值越大。     

碎屑岩储层物性非均质性的层次结构

储层物性非均质性与沉积体系内部的构成单位关系密切,可以分尺度进行研究:(1)在沉积体系级的大尺度范围内,不同的沉积体系具有不同的储集性能；在同一沉积体系中,不同的成因相孔渗值差别极大,主要取决于沉积作用过程中古水流能量和环境的变化。(2)在成因相级的中尺度范围内,各流体流动单元内部及不同的流体流动单元之间孔渗值存在明显的整体差别,这与构成流体流动单元的储层岩性相关系密切,如果叠加有不均匀的成岩作用的影响,那么流体流动单元的物性将会大大地降低。(3)在岩芯级的微尺度范围内,多孔介质具有各向异性特征。     

FACIES HETEROGENEITIES AND 3D POROSITY MODELLING IN AN OLIGOCENE (UPPER CHATTIAN) CARBONATE RAMP,SALENTO PENINSULA,SOUTHERN ITALY

Appraisal of the volumes of fluid in a carbonate reservoir will typically require a reliable predictive model. This can be achieved by combining studies of well-exposed carbonate successions with 3D models in order to obtain reliable quantitative data. In this paper, we present a detailed outcrop study and a 3D porosity model of a well-exposed Oligocene carbonate ramp (Salento Peninsula, southern Italy) to investigate the nature of small-scale facies and porosity heterogeneities. Porosity and permeability in the ramp carbonates appear to be controlled by the original mineralogy of skeletal components and by depositional textures. The aims of the study were therefore to identify the factors controlling porosity development in an undeformed carbonate ramp; to model the scale-dependent heterogeneities characteristic of the facies associations; and finally to produce a 3D model of the porosity distribution. The upper Chattian Porto Badisco Calcarenite which crops out along the coast of the Salento Peninsula consists of six lithofacies ranging from inner ramp deposits to fine-grained outer ramp calcarenites. The lithofacies are: inner ramp small benthic foraminiferal wackestone-packstones associated with (i) sea grass meadows (SG) and (ii) coral mounds (CM) consisting of coral bioconstructions with a floatstone/packstone matrix; middle ramp (iii) large rotaliid packstones to wackestone-packstones (LR), (iv) rhodolith floatstone-rudstones (RF), and (v) large lepidocyclinid packstones (LL); and (vi) outer ramp fine-grained bioclastic calcarenites (FC). A total of 38 samples collected from six stratigraphic sections (A, B, D, J, E, LO), measured in the Porto Badisco ravine, were investigated to discriminate the types of porosity. Effective and total porosity was measured using a helium pycnometer. The 3D porosity modelling was performed using PETREL™ 2016 software (Schlumberger). Four main types of porosity were recognized in the carbonates: interparticle, intraparticle, vuggy and mouldic. Primary porosity (inter- and intraparticle) is limited to middle ramp lithofacies (LL and LR) and outer ramp lithofacies (FC), whereas secondary porosity (vuggy and mouldic) was present in both inner ramp lithofacies (CM and SG) and middle ramp red algal lithofacies (RF). In the Porto Badisco carbonates, stratigraphic complexity and the distribution of primary porosity are controlled by lateral and vertical variations in depositional facies. Significant secondary porosity was produced by the dissolution of aragonitic and high-magnesium calcite components, which are dominant in the sea-grass and coral mound facies of the inner ramp and in the rhodolith floatstone-rudstones of the middle ramp. 3D models were developed for both effective and total porosity distribution. The porosity models show a clear correlation with facies heterogeneities. However of the two models, the effective porosity model shows the best correlation with the 3D facies model, and shows a general increase in effective porosity basinwards in the middle ramp facies.