混合泥质砂岩通用电阻率模型研究

基于层状泥质与分散泥质砂岩的并联导电,而分散泥质砂岩导电性等效于分散粘土和地层水为一种导电液体的纯砂岩,并考虑到在低地层水电导率(Gw)范围内分散粘土电导率(Ccl)随Gw增大而增大,建立了混合泥质砂岩通用电阻率模型.通过对该模型的影响因素分析,发现泥质分布形式对模型计算的含水饱和度有很大影响;只有Ccl变化时,地层电导率(G1)与有效含水饱和度(Sw)关系曲线的曲率相近;随Sw增大,胶结指数m对Ct与S关系曲线的影响增大,而饱和度指数n对Ct与Sw关系曲线的影响减小.通过2组分散泥质砂岩岩样实验测量数据和1组层状泥质砂岩测井资料的测试,表明该模型既适用于分散泥质砂岩地层解释又适用于层状泥质砂岩地层解释,给出的电阻率模型为通用电阻率模型.利用建立的混合泥质砂岩通用电阻率模型对海拉尔盆地高泥地区的苏1、苏3井进行处理,并将模型计算的含水饱和度与试油结果进行对比,结果表明模型计算的含水饱和度是合理的.本模型适用于高泥地区的泥质砂岩地层解释.     

基于实验的泥质砂岩含水饱和度计算方法

以泥质砂岩导电性实验和简化的岩石导电模型为基础,分析了泥质砂岩电阻率影响因素.确定了泥质附加导电的大小.淡水条件下的泥质附加导电性的大小不但与泥质体积有关,而且与地层水电阻率、孔隙度的大小有关,据此给出了一种简单的含水饱和度计算方法.实际应用表明,所给出的含水饱和度计算方法简便易行,泥质校正合理,所提供的含水饱和度比较准确,可以推广应用.     

混合泥质砂岩粘土包裹颗粒电阻率模型

砂岩油气层的低电阻率可能是由于富含分散粘土、层状泥质、高束缚水、高矿化度水、骨架导电等因素综合引起的，因此有必要建立一种适用于骨架导电且同时含分散粘土和层状泥质砂岩解释的通用电阻率模型，以提高复杂泥质砂岩储层含水饱和度的解释精度。基于层状泥质与分散粘土砂岩并联导电的观点，而分散粘土砂岩的导电可用粘土包裹颗粒电阻率模型进行描述,从而建立了考虑分散粘土和层状泥质同时存在的含油气泥质砂岩粘土包裹颗粒通用电阻率模型；通过2组分散泥质砂岩岩样实验测量数据和1组层状泥质砂岩测井资料的测试,表明该模型既适用于分散粘土砂岩地层解释又适用于层状泥质砂岩地层解释；利用建立的混合泥质砂岩粘土包裹颗粒电阻率模型，对海拉尔盆地高泥地区的苏1、苏3井进行处理，并将模型计算的含水饱和度与试油结果进行对比，结果表明模型计算的含水饱和度是合理的，故本模型适用于含油气复杂泥质砂岩地层解释。     

Estimation of shale volume using a combination of the three porosity logs

An equation was developed for evaluating the volume of shale using standard porosity logs such as neutron, density and acoustic logs. The equation is written in terms of several parameters that are readily available from well-log measurements. This equation, which takes into consideration the effect of matrix, fluid and shale parameters, applies reasonably well for many shaly formations independent of the distribution of shales. The results demonstrate the applicability of the equation to well-log interpretation as a procedure for computing shale volume in shaly sand sedimentary sections.Three key advantages of the proposed equation are: (1) it incorporates several parameters that directly or indirectly affect the determination of shale in one equation, (2) it integrates the three porosity tools for a more accurate determination, and (3) it works well in hydrocarbon-bearing formations and where radioactive material other than shale is present.Successful application of the equation to shaly sand reservoirs is illustrated by analyses of samples from the Gulf of Suez.     

低孔隙度低渗透率泥质砂岩储层中胶结指数m和饱和度指数n的计算和应用

低孔隙度低渗透率储层的孔隙结构复杂,连通性较差,孔隙中流体分布不均匀,Archie公式中系数m、n的确定存在较大误差.由传统统计分析方法求取的m和n参数会随孔隙度和含水饱和度的不同变化,使测井电阻率计算的含油气饱和度精度降低.从数学物理边界条件和低孔隙度低渗透率储层的地质特征出发,分析了低孔隙度低渗透率储层中胶结指数m和饱和度指数n的变化特征.从储层岩石的地质作用和岩石物理变化过程探讨低孔隙度低渗透率储层中地层胶结指数m随孔隙度变化的一般规律,并用渗滤门限理论(PPTT)解释这一变化过程,建立了地层胶结指数m和饱和度指数n的准确计算方法.应用新参数对应的饱和度关系对QL油田不同水淹程度的2口井进行了处理解释,获得了良好的效果.     

Neural Network Identification of Hydrocarbon Potential of Shaly Sand Reservoirs

Abstract

Hydrocarbon potential evaluation of shaly sand layers requires the adoption of certain shaly water model and also the selection of suitable conventional logging suite. The main target is how to get the accurate porosity and how to convert the apparent water saturation to true water saturation for given shaly sand layer. In this paper neural network approach is presented to replace the conventional interpretation of well logging data to better determine formation porosity and water saturation and to well identify hydrocarbon potential of clean and shaly sand layers. Two neural networks were constructed, one for prediction of porosity using six well logging data inputs: GR, LLD, RHOB, NPHI, PEF, and Δt); and water saturation using five well logging data inputs: GR, LLD, RHOB, NPHI and PEF. Shale volume was defined from GR data. Each neural network is trained using available logging data and validated using the core data before applying it to the entire well log. Neural network predicted formation porosity and water saturation for tested sections of one well. Also using the cut off values of porosity, water saturation and shale volume, the neural network defined the possible pay zones in the well. Network outputs have shown good matching with core data and the reference calculated petrophysical parameters. The developed network approach has successfully deduced porosity, water saturation and defined pay zones in a new well that projects its application for new wells.     

临南油田夏52块沙三中泥质砂岩油层的测井评价

以X射线衍射、扫描电镜、岩电实验、物性分析报告、试油等资料为基础 ,研究临南油田夏 5 2块沙三中泥质砂岩油层低电阻的成因机理 ,认为富含高岭石的泥质砂岩油层 ,泥质附加导电性不是电阻率降低的主导因素 ,更重要的是高束缚水饱和度和高地层水矿化度。泥质含量高 ,但泥质对中 -高孔隙度储层物性影响小。中 -高孔隙度岩样电阻率指数与含水饱和度 (I-Sw)关系曲线与低孔隙度岩样相比 ,差别较大 ,故将孔隙度作为选取含水饱和度解释模型和测井评价的约束条件 ,解释精度和评价级别都有所提高     

泥质砂岩声频散性考察

在Ｂｉｏｔ理论的基础上，对泥质砂岩的声频散性进行了数值计算，在实验室内常温常压下，用不同声波频率的探分别对标准件、饱和盐水岩样进行声速测量，并对岩石的声频性进行分析和探讨。实验结果表明，高孔隙度高泥质含量的泥质砂岩存在纵波声频散，孔隙度大，泥质含量高，声频散明显；对纯砂岩，当孔隙度大于２８％时存在明显纵波声频散。根据实验导出了泥质砂声频散与孔隙度的泥质含量的关系式，认为泥质含量引起的声频散是孔隙度     

泥质地层中饱和度指数的确定

Archie 公式是测井计算储层含水饱和度的重要依据之一, 但它只适应用于较纯的砂岩储层。 在泥质地层中, 电阻率指数的对数与含水饱和度的对数之间是非线性关系, 即饱和度指数随电阻率指 数的变化而变化, 而且不同孔隙结构、泥质条件下其变化不同。根据毛管理论、统计学原理、积分原理 和体积模型法, 推导出泥质地层饱和度指数与泥质含量、孔隙结构参数及电阻率指数的关系, 并确定 出泥质地层不同条件下的饱和度指数, 才能使利用Archie 公式计算的储层含水饱和度具有较高的准 确性。     

Effective Approach for Fractured Carbonate Reservoir Petrophysical Logs Interpretation in an Iranian Offshore Oil Field

Abstract

Due to the lack of information about the porosity exponent (m) from core experiments, the impossibility of comparison between the results and the core data, and, finally, inattentiveness to fractured intervals, the correct determination of the porosity exponent value in the calculation of water saturation and also the core-log correlation have generally been neglected. In this article, an analysis of the Mishrif Unit was carried out in two wells in order to properly calculate the water saturation and determine the best producing intervals. Based on fractured zones detection and the results of petrophysical evaluation in the calculation of shale volume and true matrix properties for these zones, accurate values of the porosity (matched with core data) were used to determine the porosity exponent. Hence, one of the advantages of this study is applying the method introduced simply for the fractured parts of the reservoir unit, in order to obtain the correct value for water saturation. Detecting proper producing intervals in the Mishrif Unit was executed using integrated evaluation of petrophysical data, geological data, and core data using a new method of shaly carbonate formation interpretation based on petrophysical log results. In this method, a statistical parameter, P^½, was used. The results from the application of the method show better interpretation and water saturation calculation using petrophysical logs of fractured shaly carbonate formations in combination with other available methods in the petroleum community.     

有效介质电阻率模型在含泥含钙砂岩储层中的应用

含泥含钙储层泥质和钙质成份对电阻率贡献具有复杂性,其饱和度的定量评价更加困难.通过考察储层品质指数与孔隙度的关系,确定双对数关系曲线下的斜率值,为混合泥质砂岩饱和度模型的选取提供了依据.钙质颗粒作为砂岩储层电阻率的重要影响因素,其成份的增加不仅会引起孔隙度的降低,而且引起孔隙通道曲折度的增大,从而导致地层电阻率值升高.在上述理论分析基础上,提出含泥含钙砂岩储层体积模型,并以有效介质理论为基础,建立了混合泥质含钙砂岩储层有效介质饱和度模型.该模型基于层状泥质与分散泥质砂岩并联导电以及分散泥质砂岩的有效介质SATORI电阻率模型,其中将分散泥质砂岩分成导电的砂岩骨架颗粒、不导电的油气、分散粘土颗粒、钙质颗粒、微毛管孔隙水以及可动水等6种成份,充分考虑了钙质成份的导电特性、微孔隙水的影响作用以及粘土的附加导电性等因素.经岩电实验数据拟合与实际资料处理结果表明,模型具有较强的适应性和计算精度.     

ESTIMATION OF AN EQUIVALENT SHALINESS PARAMETER USING RESISTIVITY AND SPECTROSCOPY LOGS: A TOTAL EXPANSIBLE CLAY APPROACH

We develop a method for estimating the degree of saturation in shaly sand formations based on an equivalent shaliness parameter. In shaly sands, the measured electrical conductivity is influenced by the clay content because of the charge deficit associated with the clay particles. This deficit is offset by counter-ions in a double layer whose contribution to total charge transfer is dominated by the total expansible clays. We derive an approximation for clay content and cation exchange capacity (CEC) from a linear relationship between the CEC and the total expansible clay (TEC) content of a reservoir rock. By combining mineralogy from quantitative X-ray diffraction (XRD) with wet chemistry CEC data, an expression for the counter-ions in the double layer as a function of the total expansible clays is derived. The analytical expression obtained is coupled with well-log data and compared to existing models. For determining surface conductivity, the new methodology eliminates the need for performing core measurements, subjective selection of CEC values from existing data, or the use of log-based volume-porosity translations. We show that existing popular industry models, and effective medium and electrochemical models of rock electrical conductivity can be adapted to use the new methodology. The results demonstrate a strong correlation between the estimated and measured bulk conductivity, and also resolve the scatter in estimated bulk conductivity often observed under low pore-water salinity conditions, where the ratio of surface to electrolyte conductivity approaches unity. The methodology has been applied to water saturation estimation in two Australian petroleum wells, Yolla-4 and Cliff Head-4. The results demonstrate that this technique provides better estimates of water saturation in both low conductivity contrast pays and tight pays compared to existing approaches.     

混合泥质砂岩有效介质通用HB电阻率模型在高泥储层中的应用

基于Berg提出的层状泥质或分散泥质砂岩有效介质HB电阻率模型，并在总孔隙中考虑粘土结合水的体积，但不考虑粘土结合水与地层水导电性的差别，将粘土结合水与地层水的导电性差别归结到粘土颗粒导电中，建立了混合泥质砂岩有效介质通用HB电阻率模型。通过研究混合泥质砂岩有效介质通用HB电阻率模型的求解方法，表明模型导出的关于Swt的方程是一个一元二次方程，可用求根公式求解，解法非常简单。通过对混合泥质砂岩有效介质通用HB电阻率模型中各参数的确定方法进行研究，给出了有效的参数确定方法。利用建立的混合泥质砂岩有效介质通用HB电阻率模型，对海拉尔盆地高泥地区的苏1、苏3井进行处理，并将模型计算的含水饱和度与试油结果进行对比，结果表明模型计算的含水饱和度是合理的。该模型适用于高泥地区的泥质砂岩地层解释。     

碳氧比能谱测井解释的泥质校正

申本科．碳氧比能谱测井解释的泥质校正．测井技术，１９９７，２１（３）：２２１～２２６碳氧比测井解释方程中的碳氧比值是在简单岩性的模拟地层中测得的，该值往往忽略了实际泥质砂岩或复杂岩性地层中泥质含量对碳氧比值的影响。通过对岩心样品的中子活化分析，Ｘ射线衍射法测量和定碳仪测量，确定出岩心中泥质砂岩骨架的碳氧比值，从而找到泥质对碳氧比值的影响因素。经校正后的碳氧比值可以准确地求取储层的含油饱和度。     

Effective porosity determination in clean/shaly formations from acoustic logs with applications

Reliable evaluation of porosity in clean and/or shaly formations requires knowledge of matrix (type and nature), fluid, shale volume and shale transit time affecting the determination of such parameter. If all are linked together in a compatible and quantitative way, good results for porosity are obtained. However, the objective assigned to this paper is to introduce an equation for estimating effective porosity in clean/shaly formations from sonic logs. This is considered as an acoustic-V_sh model that represents a few advantages over the other equations. In addition to being a simpler expression, it treats the shale effect as a correction term subtracted from the clean–sand term (i.e., the equation clearly points out the practical aspect of the shale effect and its correction.). Also, it gives reliable and acceptable values for porosity with Δ_t ranging between 70 to 110 μs/ft and Δ_tsh from 70 to 95 μs/ft (i.e., good results could be achieved with variable shale transit time). After being tested among a wide variety of samples representing different lithologies, the equation gives acceptable values of porosity with reasonable accuracy specifically where no porosity tools other than sonic logs are available. Successful application to real field data in the Gulf of Suez Basin of Egypt and Williston Basin in the USA, is also demonstrated.     

某油田低孔隙度低渗透率泥质砂岩储层岩电实验及应用

从某油田中、低孔隙度及渗透率储层岩心在不同溶液矿化度条件下的岩电参数实验结果研究可知,低孔隙度低渗透率储层的岩电参数明显不同于中、高孔隙度储层,中、高孔隙度储层的孔隙度指数和饱和度指数基本不随溶液矿化度的变化而变化,但是低孔隙度低渗透率储层的孔隙度指数和饱和度指数分别随溶液矿化度的增大而增大.根据岩电实验结果,分别建立了孔隙度指数、饱和度指数随不同孔隙度和溶液电阻率变化的方程,改进了常用的计算含水饱和度的Archie模型.通过所建模型在某气田低孔隙度低渗透率储层测井解释中的实际应用,取得了满意的效果.表明开展低孔隙度低渗透率储层的岩石物理实验,对于建立测井解释模型,进而评价该类储层,具有重要的研究价值.     

一种同时反演地层水电阻率和含水饱和度的方法

对于低孔低渗、泥质含量较高的泥质砂岩储层,我们提出了一种新的模型来反演地层水电阻率和含水饱和度。它首先对阿尔奇公式进行了泥质校正和粘土附加导电校正,同时采用变m指数部分补偿了低孔低渗的影响,然后利用得到的模型通过规划求解的方法同时反演得到了含水饱和度和地层水电阻率。计算结果与试油资料的对比证实了该方法的可行性。     

速度的三元介质模型

在探井岩心分析与测井解释资料基础上,结合波速机理分析,提出砂泥质岩波速的二级近似式;并将时间平均方程由二元推广到三元,可同时求取砂质岩的泥质分量和孔隙率。文中给出了在塔里木盆地储层研究中的应用实例。     

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酒泉盆地青西坳陷青南凹陷柳沟庄—窟窿山构造下沟组储层岩性主要为低孔、低渗砂砾岩类和泥云岩类，岩石矿物成分复杂、泥质含量高、黄铁矿富集、裂缝类型及组合形式复杂，属典型复杂岩性裂缝—孔隙型储层。在这类复杂岩性裂缝—孔隙型储层中，自然伽马等测井曲线不能很好指示地层中的泥质含量，常规测井资料难以准确识别地层的岩石矿物成分，单条测井曲线与岩心孔隙度之间的关联度低，采用常规的孔隙度测井计算方法存在明显的缺陷，孔隙度计算精度远远不能满足储层评价和储量计算要求。文章利用岩心分析数据和测井信息等资料，采用3层BP神经网络进行学习训练，得到砂砾岩岩类和泥云岩岩类的孔隙度计算模型。利用该模型计算储层孔隙度，其结果与岩心分析孔隙度比较，平均误差小于1.5%，能满足储量计算要求。在实际应用中见到良好效果，孔隙度计算精度明显得到提高。     

多浓度下泥质砂岩电学性质实验研究

依据多浓度岩石电性实验，研究不同浓度下泥质砂岩的束缚水相对体积及其导电特性，可以揭示束缚水饱和度和地层水浓度的变化所引起的泥质砂岩导电特性的变化。研究表明，不同浓度下的泥质砂岩有不同的束缚水饱和度，而且随饱和溶液浓度的增大而减小。束缚水条件下岩石的电阻率受地层水电阻率、束缚水饱和度、泥质附加导电性影响，在地层水浓度较低情况下，由于较高的束缚水含量和泥质附加导电性，岩石的电阻率也可能呈现低电阻率特征。