电成像测井资料在裂缝成因分析中的应用

以塔里木盆地为例,探讨高分辨率电成像测井资料在裂缝成因分析中的应用。根据电成像测井图像解释,利用裂缝图像的颜色(或灰度)和产状特征,结合岩芯标定和常规测井资料,可以有效地区分构造裂缝与非构造裂缝、张裂缝与剪裂缝,确定裂缝充填与否和充填物的成分,以及裂缝的溶蚀改造程度。利用从电成像测井图像上提取的共轭裂缝的产状信息,还可以恢复裂缝形成时古构造应力场的方向。     

Integration of outcrop and borehole image logs for high-resolution facies interpretation: example from a fluvial fan in the Ebro Basin, Spain

Electrical borehole image logs yield high-resolution information about variations in micro-resistivity along the borehole wall. To interpret these variations in terms of sedimentary structures and lithofacies types, calibration with real rock is needed. Normally, the only real rock available is core, and this only provides one-dimensional information. In this paper, the interpretation of fluvial facies types from borehole image logs was established by direct comparison with outcrops. Four fluvial facies associations were established in an outcrop study of a low net-to-gross fluvial succession: (i) meandering rivers, (ii) braided rivers, (iii) crevasse deltas, and (iv) crevasse splays. The lithofacies characteristics and palaeocurrent distributions of each fluvial facies association were established. Two 200 m deep wells were drilled behind the cliff face outcrops. One well was cored to a depth of 150 m and borehole image logs were recorded in both wells. The wells were correlated with the outcrop. The borehole image logs were analysed by their vertical colour succession and the dipmeter pattern. Image log facies were established, and these were interpreted in terms of the fluvial facies associations encountered in the corresponding outcrops. The study of borehole image logs yields a set of diagnostic criteria for a detailed fluvial facies interpretation and the establishment of depositional trends, and thus provides a powerful tool for the direct interpretation of fluvial facies in a reservoir setting.     

成像测井缝洞解释评价研究进展

综合露头刻度井、数值模拟和物理模拟的实验结果对微电阻率扫描成像测井缝洞解释评价的研究进展进行了总结和探讨,分别包括岩芯归位、缝洞刻度率、岩芯和成像裂缝参数的差异性,以及裂缝宽度和地层孔隙度的计算。岩芯归位确定了缝洞体在地层中的深度和方位。电成像测井对过井眼未充填缝和孔洞发育段的刻度率为100%,而单个孔洞在岩芯和电成像测井中通常无法一一对应。单条裂缝的倾角或井周长度在岩芯和成像测井中具有较高的相关性,而裂缝宽度的相关性一般。数模和物模的结果表明电成像测井裂缝宽度的计算受多种因素影响,当裂缝的视宽度大于0.1 mm时,电成像测井计算的裂缝宽度和裂缝视宽度基本一致,当小于0.1 mm时,电成像测井计算的宽度值误差较大。目前电成像测井通过孔隙度谱法和图像分割法计算地层的孔隙度,但都受限于除孔洞的其他低阻地质体的影响,因此需要加强岩芯刻度的功能。     

成像测井缝洞解释评价研究进展

综合露头刻度井、数值模拟和物理模拟的实验结果对微电阻率扫描成像测井缝洞解释评价的研究进展进行了总结和探讨,分别包括岩芯归位、缝洞刻度率、岩芯和成像裂缝参数的差异性,以及裂缝宽度和地层孔隙度的计算.岩芯归位确定了缝洞体在地层中的深度和方位.电成像测井对过井眼未充填缝和孔洞发育段的刻度率为100％,而单个孔洞在岩芯和电成像...     

多源遥感数据在西准噶尔哈拉阿拉特山地区1:5万地质填图中的对比研究

以ETM、SPOT5和Quickbird为主要信息源,在哈拉阿拉特山地区开展1:5万区域地质填图,对该地区的地层单元、中—小规模地质体(如岩脉、小岩体和火山口)和地质构造特征进行了详细地遥感解译分析,并开展了大量的遥感野外地质调查验证.结果表明,采用彩色空间HSV变换融合法将SPOT5高精度遥感图像数据与ETM图像数据...     

用测井资料确定储层三孔隙组分的理论与方法

分析了岩石的孔隙和孔隙结构与岩石的成分尤其是泥质和粘土之间的密切联系,并从常规测井、核磁测井反映的孔隙度、泥质含量等参数入手,研究建立了常规测井资料划分三种孔隙组分的理论和实现方法,结合实际测井资料,对这些方法进行了检验。实例表明,根据该理论和方法确定的储层的三孔隙组分——粘土水孔隙、微孔隙水孔隙以及自由水孔隙组分可以取得较好的效果。     

埕岛油田水淹层测井响应原理及识别

本文依据油层导电原理和阿尔奇公式建立了埕岛油田水淹层解释的理论基础。在对埕岛油田注入水水性分析后,确定了水淹层的电性变化特征;进行水淹层解释的过程中,根据不同的测井曲线特征分别建立了自然电位基线偏移法、自然电位与电阻率对应分析法、交汇图版法和综合分析法等水淹层解释方法,并在埕岛油田水淹层解释中得到了成功应用,为埕岛油田剩余油饱和度解释奠定了基础。     

西大明山铅锌矿田成矿带地质解译及矿化蚀变遥感信息提取研究

通过收集西大明山铅锌矿田成矿带地质、遥感、已知矿点等资料,利用TM遥感图像处理技术,在假彩色合成及比值假彩色合成图像上提取与铅锌矿成矿有关的构造、围岩蚀变信息,并在TM图像上地质解译出线性、环形构造,将所获得的多种遥感信息进行复合。结合该区域已知资料,综合圈定出5个成矿远景区,为西大明山地区进一步开展矿产资源调查工作提供了基础资料和科学依据。     

Well log data analysis for lithology and fluid identification in Krishna-Godavari Basin,India

Well log analysis provides the information on petrophysical properties of reservoir rock and its fluid content. The present study depicts interpretation of well log responses such as gamma ray, resistivity, density and neutron logs from six wells, namely W-1, W-2, W-9, W-12, W-13 and W-14 under the study area of Krishna-Godavari (K-G) basin. The logs have been used primarily for identification of lithology and hydrocarbon-bearing zones. The gamma ray log trend indicates deposition of cleaning upward sediment. Coarsening upward, clayey-silty-sandy bodies have been evidenced from the gamma ray log. Gas-bearing zones are characterised by low gamma ray, high deep resistivity and crossover between neutron and density logs. Total 14 numbers of hydrocarbon-bearing zones are identified from wells W-9, W-12, W-13 and W-14 using conventional log analysis. Crossplotting techniques are adopted for identification of lithology and fluid type using log responses. Crossplots, namely P-impedance vs. S-impedance, P-impedance vs. ratio of P-wave and S-wave velocities (Vp/Vs) and lambda-mu-rho (LMR), have been analysed to discriminate between lithology and fluid types. Vp/Vs vs. P-impedance crossplot is able to detect gas sand, brine sand and shale whereas P-impedance vs. S-impedance crossplot detects shale and sand trends only. LMR technique, i.e. λρ vs. μρ crossplot is able to discriminate gas sand, brine sand, carbonate and shale. The LMR crossplot improves the detectability and sensitivity of fluid types and carbonate lithology over other crossplotting techniques. Petrophysical parameters like volume of shale, effective porosity and water saturation in the hydrocarbon-bearing zones in these wells range from 5 to 37%, from 11 to 36 and from 10 to 50% respectively. The estimated petrophysical parameters and lithology are validated with limited core samples and cutting samples from five wells under the study area.     

砂泥岩薄互层测井资料解释方法

从分析薄互层的特征入手,采用反褶积方法对单条测井曲线做提高分辨率的处理,并调整电阻率测井曲线,使其与提高了分辨率的泥质含量及孔隙度测井曲线的纵向分辨率协调、在此基础上,按一定的解释模型计算出孔隙度和饱和度等参数。实际计算表明,本方法改善了储集参数的评价,降低了含水饱和度。     

Identification of sandstone body types by computer method

Three sandstone body types—progradational (coarsening upward), aggradational (coarsening downward), and block—can be identified by computer using the least-squares method. The basic data are the digital gamma () ray and sonic log data. Other logs such as SP and resistivity (or conductivity) may also be used with minor changes in the computer program. A statistical program to compute the percent of each of these three types in a specified geologic unit was also written and run for several wells in the Beaufort Basin, Canada. An areal mapping of these calculated results shows the features of progradational sedimentation in this area. The percentage of progradational sandstones increases northward in a seaward direction. The amount of sandstones usually decreases in this direction.     

SAR遥感数据用于岩性识别与分类的研究

利用新疆北部山区雷达遥感数据,通过遥感数字图像处理与增强,生成雷达遥感假彩色合成影像应用于岩性判释。对不同岩性岩石,利用极化雷达提供的地表岩石的多种散射信息作为输入进行计算机神经网络分类,岩性识别分类的总精度为62.6%。与常规雷达数据分类对比,分类精度与岩石识别正确率均有显著提高。     

Vegetation change detection from NOAA polar orbiting satellites

A Method is proposed for detecting vegetation change using global area coverage data from the NOAA-7 Advanced Very High Resolution Radiometer. Other methods of vegetation change detection, such as baseline images, are discussed, but not demonstrated. Vegetation Change Detection Images are produced by combining three separate weekly composites of Channel 2 minus Channel 1 AVHRR data. This compositing method takes the highest value of the differenced data for each week period and each pixel location. Three such weekly composites red imaged by individual red, green and blue CRT color guns respectively and then combined to form a color composite. The Vegetation Change Detection Image has 20 km resolution. It can be used to show an entire continent on a single image when the data point to CRT pixel ratio is 1:1. The vector vegetation change (magnitude and direction) is depicted by the color pattern resulting from the relative amount of red, green and blue placed in the pixel due to the individual weekly color composites. If there is no greenness change at a pixel location the amount of red, green and blue will be the same and a gray scale color results. The VCDI could provide a timely first alert for identifying regional and global agricultural changes.Doubts have been expressed about the reliability of this satellite data because of the unknown (and variable) effects of atmospheric attenuation. A basic qualitative rather than quantitative analysis of the data has been suggested as the correct approach.     

Sulfur concentration at sulfide saturation (SCSS) in magmatic silicate melts

The sulfur concentration in silicate melts at sulfide saturation (SCSS) was experimentally investigated in a temperature range from 1150 to 1450 °C and a pressure range from 500 MPa to 1 GPa in a piston-cylinder apparatus. The investigated melt compositions varied from rhyolitic to basaltic and water concentrations varied from 0 to ∼9 wt%. All experiments were saturated with FeS melt or pyrrhotite crystals. Temperature was confirmed to have a positive effect on the SCSS. Experimental oxygen fugacities were either near the carbon-carbon monoxide buffer or one log unit above the nickel-nickel oxide buffer, and found to positively affect the SCSS. Combining our results with data from the literature we constructed a model to predict the SCSS in melts ranging in composition from komatiitic to rhyolitic, with water concentrations from 0 to 9 wt%, at pressures from 1 bar to 9 GPa and oxygen fugacities between ∼2 log units below the fayalite-magnetite-quartz buffer to ∼2 log units above it. The coefficients were obtained by multiple linear regression of experimental data and the best model found for the prediction of the SCSS is:

     

Exploration in the Minnelusa Sandstone using a digital well log database

The Pennsylvanian Minnelusa Sandstone is one of the most prolific oil producing formations in the Powder River Basin of Wyoming. Virtually all petroleum accumulation is in stratigraphic traps, with much production from paleotopographic highs beneath a regional unconformity. Oil is trapped in dune sands. Both thickness of sandstones and their cementation vary greatly over short distances. The exploration area comprises 60 townships and 3400 wells. About 95% of the wells have sonic ray logs. The database includes cartographic data, formation, and zone tops picked by a single geologist, and normalized ray and sonic logs. Great emphasis is placed on data quality. Newly released logs are added monthly. This database provides the exploration geologist with a new way of doing subsurface interpretation. Free from demands of gathering and tabulating basic data, the geologist is able to do more creative work. A new and original concept—one that would take several person-months of manual effort to work out—can be mapped out and evaluated in less than a week.     

Textural segmentation of digital rock images into bedding units using texture energy and cluster labels

The texture of digital rock images, as recorded, for instance, with borehole imaging devices, is shown to reflect different bedding types. Textural segmentation of borehole images, therefore, subdivides the recorded sequence into bedding units. We show that a textural segmentation algorithm based on the concept of texture energy achieves good results when compared with synthetic as well as real data in which petroleum geologists have performed zonations on cores. Texture energy involves filtering of the original image with a set of texture sensitive masks. The filtering is done as a finite convolution over the size of the masks. On the resulting images the variance is computed over a relatively large sliding window, which, in its practical implementation, covers the full width of the image. The resulting nine one-dimensional curves are then clustered hierarchically into a user-determined number of image texture or lithological bedding classes. Principal component analysis previous to clustering can be used to reduce redundancy in the data. A recurring and relatively ill-defined problem in this field are macro-textures, i.e., the cyclic interbedding of two or more bedding types. We show that sliding Fourier transforms and variable mask scale can successfully address the zonation of macro-textures. In general, the method gives best results with mask sizes equivalent to 2–4 centimeters, reflecting the length scale at which the investigated geological bedding seems to have its highest variation.     

A New Algorithm for Borehole Electromagnetic Measurements Employing Lambert W Function

The Lambert W function is defined to be the multivalued inverse of the function w we ^w . It has been widely used in many fields. In this paper, we developed an accurate algorithm for calculating apparent formation conductivity and dielectric constant from electromagnetic logs by making use of Lambert W function. Transforming the complicated nonlinear system into a linear system of much simpler format, this new algorithm can achieve a much higher accuracy of data processing and provide physically meaningful results over the full frequency band of electromagnetic logs. In the frequency band of induction logs (<20 MHz) this algorithm eliminates the complicated procedure for correcting for the skin effects. It also removes the conventional limitation of for induction logs, and therefore, makes accuracy of induction log measurements no longer dependent on the true formation conductivity. In the frequency band of 20–100 MHz, this method can obtain accurate formation conductivities and dielectric constant simultaneously. Theoretical analysis, numerical modeling, and field data processing cases of Oklahoma formation demonstrate the advantages of this new method over traditional methods. The algorithm for this method is easy to implement and it can be used with electronic hardware to produce accurate formation conductivity and dielectric logs directly.     

The solubility of platinum and gold in NaCl brines at 1.5 kbar, 600 to 800°C: A laser ablation ICP-MS pilot study of synthetic fluid inclusions

The concentration and distribution of Pt and Au in a fluid-melt system has been investigated by reacting the metals with S-free, single-phase aqueous brines (20, 50, 70 wt% eq. NaCl) ± peraluminous melt at a confining pressure of 1.5 kbar and temperatures of 600 to 800 °C, trapping the fluid in synthetic fluid inclusions (quartz-hosted) and vesicles (silicate melt-hosted), and quantifying the metal content of the trapped fluid and glass by laser ablation ICP-MS. HCl concentration was buffered using the assemblage albite-andalusite-quartz and fO₂ was buffered using the assemblage Ni-NiO. Over the range of experimental conditions, measured concentrations of Pt and Au in the brines (, ) are on on the order of 1-10³ ppm. Concentrations of Pt and Au in the melt (, ) are ∼35-100 ppb and ∼400-1200 ppb, respectively. Nernst partition coefficients (, ) are on the order of 10²-10³ and vary as a function of (non-Henry’s Law behavior). Trapped fluids show a significant range of metal concentrations within populations of inclusions from single experiments (∼ 1 log unit variability for Au; ∼2-3 log unit variability for Pt). Variability in metal concentration within single inclusion groups is attributed to premature brine entrapment (prior to metal-fluid-melt equilibrium being reached); this allows us to make only minimum estimates of metal solubility using metal concentrations from primary inclusions. The data show two trends: (i) maximum and average values of and in inclusions decrease ∼2 orders of magnitude as fluid salinity () increases from ∼4 to 40 molal (20 to 70 wt % eq. NaCl) at a constant temperature; (ii) maximum and average values of increase approximately 1 order of magnitude for every 100°C increase temperature at a fixed . The observed behavior may be described by the general expression:

     

测井曲线的岭回归及岩性柱状图的自动拾取

本文介绍了地球物理勘探测井资料的计算机处理中,采用岭回归方法对测井曲线DLW、HG、HGG、DZW进行处理,直接生成岩性柱状图。简要介绍了岭回归的原理和方法并通过实例,经过样本训练,给出了岩性的预测公式,计算结果和计算机绘制的岩性柱状图。该方法的实现对测井资料的计算机解释和成图有较大现实意义。