高阻地层HDIL阵列感应影响因素分析与校正方法

近年来,四川盆地川中深层灯影组和龙王庙组天然气勘探中越来越多地使用油基泥浆,使得裸眼井电阻率测井只能选择阵列感应仪器。该地区目的层致密碳酸盐岩普遍表现为中高电阻率,典型气层的电阻率一般在500Ω·m以上甚至高达2000Ω·m,使得测量电导率的感应测井仪器接收的信号弱,叠加深层高温等因素的影响,采集的信号常出现负值,软件聚焦处理结果常出现平头现象,不能用于储层识别和气层评价。采用有限元模拟算法,分析泥浆电阻率、侵入半径及原状地层电阻率等单因素对阵列感应测井响应的影响规律,明确了各环境因素对感应测量信号的影响规律。结果表明,地层与泥浆电阻率对比度对测量信号有明显影响,当对比度接近于1时,各子阵列的误差较小,而侵入深度是另一个重要影响因素。总体上,较长源距的子阵列受各种因素的影响相对较小。针对实际资料的特点,提出一种基于Archie公式的原始电导率信号约束校正方法,对约束校正后的数据再开展软件聚焦,其结果得到明显改善。

Review of the studies on climate change since the last inter-glacial period on the Tibetan Plateau

As the ＂Third Pole＂ of the world, the Tibetan Plateau has important effects on climate of its surrounding areas and even the whole world. Many results have been achieved on climate change since the last inter-glacial period in recent decades from ice core, tree-ring and lake sediment records over the Tibetan Plateau. In this paper, we review these achievements, especially those in the special periods. During the last inter-glacial period, temperature went down rapidly and went up slowly. The temperature record of the last glacial period is consistent with Greenland ice core records, also having own features over the Tibetan Plateau. Younger Dryas event agrees with the records from Europe and Greenland. Generally speaking, it is warm in the Holocene, and temperature has been rising gradually in the last 2000 years and gone up rapidly in recent decades. Climate changes on different time scales on the Tibetan Plateau occurred earlier and the change amplitude is larger than those in other parts of China.

地层评价与测井技术新进展:第64届SPWLA年会综述

简要介绍了第64届岩石物理学家和测井分析家协会(SPWLA)年会的主要内容,重点以常规/非常规储层的地层评价、饱和度及流体分析等15个专题详细分析了年会上交流的127篇学术论文,以此为基础对近年来岩石物理与测井基础理论研究、测井新仪器与新方法研发、复杂油气藏及非常规油气藏综合评价技术等领域的最新进展进行总结与分析,对测井方法、测井仪器及测井解释评价的国际发展趋势进行分析讨论,并对中国测井技术的发展提出了合理化建议。

Calculation of oil saturation in clay-rich shale reservoirs:A case study of Qing 1 Member of Cretaceous Qingshankou Formation in Gulong Sag,Songliao Basin,NE China

The targeted reservoir,which is referred as the first member of Cretaceous Qingshankou Formation in Gulong Sag,Songliao Basin,NE China,is characterized by the enrichment of clay and lamellation fractures.Aiming at the technical challenge of determining oil saturation of such reservoir,nano-pores were accurately described and located through focused ion beam scanning electron microscopy and quantitative evaluation of minerals by scanning electron microscopy based on Simandoux model,to construct a 4D digital core frame.Electrical parameters of the shale reservoir were determined by finite element simulation,and the oil saturation calculation method suitable for shale was proposed.Comparison between the results from this method with that from real core test and 2D nuclear magnetic log shows that the absolute errors meet the requirements of the current reserve specification in China for clay-rich shale reservoir.Comparison analysis of multiple wells shows that the oil saturation values calculated by this method of several points vertically in single wells and multiple wells on the plane are in agreement with the test results of core samples and the regional deposition pattern,proving the accuracy and applicability of the method model.

Forward simulation of array laterolog resistivity in anisotropic formation and its application

A scaling-down experiment system of array laterolog resistivity was developed, and a corresponding formation model was built by 3 D finite element numerical method to study the effect of different factors on the logging response quantitatively. The error between the experimental and numerical results was less than 5%, validating the reliability of the numerical simulation method. The single factor analysis of the formation relative dip, resistivity anisotropy and drilling fluid invasion was carried out by numerical simulation method, and the results show that:(1) The increase of relative dip can lead to the increase of formation resistivity, but the increasing value is relatively small, and the values of five array resistivity curves will reverse when the relative dip angle reaches a certain degree.(2) The increase of anisotropy coefficient λ can also cause the formation resistivity to rise, and the resistivity will increase by about 10% when λ increases from 1.0 to 1.5 in vertical wells.(3) Drilling fluid invasion has a more significant effect on the logging response than the former two factors. The order of the five curves will change due to drilling fluid invasion in anisotropic formation and the change rule is contrary to resistivity anisotropy. Taking the logging data of the Yingxi oilfield in the Qaidam Basin as an example, an anisotropic formation model considering drilling fluid invasion was built, and the numerical simulation results from the above methods were basically consistent with the logging data, which verified the accuracy of the method again. The results of this study lay a theoretical foundation for multiple-parameter inversion in anisotropic formation under complex well conditions.

A new permeability calculation method using nuclear magnetic resonance logging based on pore sizes: A case study of bioclastic limestone reservoirs in the A oilfield of the Mid-East

It is difficult to accurately obtain the permeability of complex lithologic reservoirs using conventional methods because they have diverse pore structures and complex seepage mechanisms.Based on in-depth analysis of the limitation of classical nuclear magnetic resonance(NMR)permeability calculation models,and the understanding that the pore structure and porosity are the main controlling factors of permeability,this study provides a new permeability calculation method involving classifying pore sizes by using NMR T_2 spectrum first and then calculating permeability of different sizes of pores.Based on this idea,taking the bioclastic limestone reservoir in the A oilfield of Mid-East as an example,the classification criterion of four kinds of pore sizes:coarse,medium,fine and micro throat,was established and transformed into NMR T_2 standard based on shapes and turning points of mercury intrusion capillary pressure curves.Then the proportions of the four kinds of pore sizes were obtained precisely based on the NMR logging data.A new NMR permeability calculation model of multicomponent pores combinations was established based on the contributions of pores in different sizes.The new method has been used in different blocks.The results show that the new method is more accurate than the traditional ones.

致密砂岩电学各向异性测井评价与声电各向异性一致性分析

针对致密砂岩各向异性反演问题,提出了从阵列侧向测井和微电阻率扫描成像测井提取电阻率各向异性的新方法,并对电学和声学各向异性的一致性开展研究。阵列侧向测井包含电阻率各向异性信息,但数模表明钻井液侵入是影响其响应特征的主要因素,其次分别是相对倾角θ和电各向异性系数λ。提出在已知θ前提下分步确定侵入半径ri、冲洗带电阻率Rxo、原状地层电阻率Rt初始值的分级反演以确定ri、Rxo、Rt和λ的方法。微电阻率扫描成像测井是对不同方位上电阻率分布特征的刻画,可以通过对比不同方位上电阻率的大小及水平、垂直方向的电阻率差异来提取电各向异性信息。致密砂岩矿物颗粒的定向排列和裂隙发育等因素是决定其各向异性的主要内在因素,由此产生了电各向异性及声各向异性,二者的强弱具有一致性。对多口井的测井资料分析表明,从阵列侧向、微电阻率扫描成像和交叉偶极声波测井分别提取的电、声各向异性强弱程度相互匹配,验证了反演方法的准确性及刻画不同岩石物理各向异性变化趋势的一致性。该研究为致密砂岩的各向异性评价提供了更多的技术手段。

塔里木盆地鹰山组致密碳酸盐岩地震岩石物理特征

塔里木盆地鹰山组海相碳酸盐岩储层地震岩石物理变化规律研究相对薄弱,不足以支撑地震勘探需要。通过利用微米CT和铸体薄片图像对塔里木盆地古城与哈拉哈塘地区奥陶系鹰三段致密碳酸盐岩样品进行了系统岩石结构与孔隙结构特征分析,并运用脉冲传输法与应力—应变法测量了样品超声波速度与地震频段速度,基于实验结果分析了深层致密碳酸盐岩样品岩石物理特征的变化规律。研究结果表明:碳酸盐岩样品物性与地震弹性性质整体变化规律受岩石孔隙结构特征影响,致使样品在孔隙度—渗透率、密度—速度以及孔隙度—速度变化关系上表现出明显非线性特征,而不能用简单统计模型表征;致密碳酸盐岩样品纵、横波速度关系可用简单的线性统计模型表征,在速度比上灰岩、灰质云岩、白云岩以及硅质云岩呈逐渐减小趋势,可利用速度比及其他含有横波信息的弹性参数进行岩性识别;样品在地震频段表现出明显的频散现象(5~200 Hz),微裂隙—溶蚀孔隙型样品、微裂隙型样品与溶蚀孔隙型样品在频散与衰减特征上存在明显差异,微裂隙—溶蚀孔隙型样品具有相对较强的频散与衰减特征。依据储层岩石地震弹性性质变化特征给出了深层致密碳酸盐岩岩性、储层类型以及孔隙流体识别与预测的岩石物理标准,为国内深层碳酸盐岩储层地震预测提供了可靠依据。

富黏土页岩储集层含油饱和度计算方法——以松辽盆地古龙凹陷白垩系青山口组一段为例

针对松辽盆地古龙凹陷白垩系青山口组一段富含黏土且页理缝发育的页岩地层含油饱和度计算难题,基于Simandoux模型,通过聚焦离子束扫描成像及扫描电镜矿物定量评价分析配套测试和对比分析,对纳米孔准确描述和定位,构建四维数字岩心格架,采用有限元模拟确定页岩储集层岩石电性参数,提出了确定页岩岩石电性参数和含油饱和度计算的方法。通过与岩心数据和二维核磁共振测井饱和度结果对比表明,采用该方法得到的富黏土页岩储集层含油饱和度公式误差符合现行国家储量规范要求。经多井对比分析表明,在单井纵向上和多井平面上,计算的含油饱和度与取心样品分析化验结果及区域沉积规律吻合,进一步验证了该方法模型的精度和适用性。

致密砂岩岩电响应规律与饱和度评价方法

针对致密砂岩储集层在中低含水饱和度下岩石电性响应规律不明确的问题,提出高速离心驱替岩电和不同含水饱和度下核磁共振T2谱联测的实验方法,可驱替渗透率小于0.1×10-3μm2的致密砂岩岩心,为致密砂岩电性研究提供可靠实验手段。通过开展高分辨率CT扫描、MAPS和Qemscan等配套实验,构建基于多源信息融合的多矿物组分精细三维数字岩心,采用有限元数值模拟方法,得到实验室条件下无法获得的低含水饱和度下致密砂岩电性响应。通过实验与数值模拟相结合,明确了复杂孔隙结构致密砂岩电性响应规律,建立了基于孔隙结构的变岩电参数饱和度评价方法。对鄂尔多斯盆地延长组7段致密砂岩储集层多口井测井资料处理分析表明,该方法能够获得更准确的含油饱和度,为致密砂岩油气测井精细评价提供了新思路和新方法。

各向异性地层阵列侧向电阻率响应仿真模拟及应用

研制等比例缩小阵列侧向测井物理模拟实验系统,并基于三维有限元数值方法建立相应地层模型,定量研究不同因素对测井响应的影响。实验与数值模拟结果误差小于5%,验证了数值模拟结果的可靠性,进一步利用数值模拟方法对地层相对倾角、电各向异性和钻井液侵入进行单因素分析,研究结果表明:①各向异性地层中相对倾角增加会引起电阻率的抬升,但是对电阻率的抬升值相对较小,相对倾角达到一定角度时会引起阵列电阻率5条曲线数值高低出现翻转;②电各向异性系数λ值增加也会引起地层电阻率的抬升,直井条件下λ值由1.0增加到1.5时会导致电阻率抬升约10%;③相比于地层相对倾角和电各向异性,钻井液侵入对测井响应影响更显著,并且各向异性地层中低阻钻井液侵入会改变5条曲线的顺序,其规律与电各向异性相反。以柴达木盆地英西油田实际测井资料为例,构建考虑钻井液侵入的各向异性倾斜地层模型,利用上述方法正演模拟结果与实测曲线变化规律基本一致,再次验证了该方法的准确性。为复杂井况各向异性地层多参数反演提供了理论依据。

基于空间响应分布函数的水平井补偿密度测井快速正演模拟

水平井中补偿密度测井的正演模拟主要采用蒙特卡罗方法,计算时间较长,难以满足生产实时评价的需求。提出一种补偿密度测井快速正演模拟的新方法,引入空间响应分布函数表征伽马场分布及地层不同体积元对探测器计数贡献。采用蒙特卡罗程序建立快速正演模拟所需数据库,利用空间响应分布函数计算不同地层区域对探测器计数贡献,实现补偿密度测井的快速正演模拟。数值模拟结果表明,新方法的计算精度与蒙特卡罗方法一致,但计算速度提高十万倍以上,能够满足水平井井眼轨迹与地层关系确定中快速正演的需求。

斜井各向异性地层阵列侧向测井资料快速分级反演方法

针对斜井各向异性地层阵列侧向测井响应复杂、资料处理难等问题,提出一种快速分级反演方法。首先,分析侵入、各向异性和地层倾角等对阵列侧向测井响应的影响,并对敏感性进行分级;然后,根据深-中-浅电阻率曲线的分离特性,建立不同倾角条件下的数据库;根据敏感性级别和正演数据库,依次确定各个地层参数的最优反演初值;最后,结合Levenberg-Marquardt算法,提升反演结果的准确性。进一步将反演方法应用于青海油田实际资料,利用岩心分析数据标定和验证,取得了良好的应用效果。结果表明固定倾角条件,阵列侧向测井对侵入深度、电阻率和各向异性的敏感性依次降低;正演数据库的方法解决了传统三维反演速度慢的难题,初值分级选取策略则保证了反演算法的全局寻优能力。

敦煌莫高窟大气颗粒物中水溶性离子变化及来源解析

为探明莫高窟大气颗粒物污染特征,采集了2014年4-12月第16窟及72窟外环境中大气颗粒物PM2.5和PM10~2.5样品,对比分析了样品中水溶性离子变化及影响因素,通过主成分分析法解析了其主要来源。结果表明:(1)窟区主风向为南风,起沙风频率仅为0.01%,不利于污染物的扩散;(2)窟外PM2.5和PM10~2.5、窟内PM2.5和PM10~2.5中水溶性离子总浓度分别为6.1±4.0μg·m^(-3)、12.2±9.1μg·m^(-3)、3.7±0.8μg·m^(-3)和7.5±1.6μg·m^(-3),SO_(4)^(2-)、Ca^(2+)、NO3^(-)、Na^(+)及Cl^(-)是主要组成,SO42-、NO3-和Ca2+之和在窟外和窟内PM2.5和PM10~2.5中占总离子比例分别为79.24%,76.81%,80.61%及77.74%,二次离子主要来自固定污染源;(3)PM2.5与PM10~2.5中各离子浓度的比值在窟外、内分别为0.33~0.88、0.25~0.94,9种水溶性离子在不同粒径粒子中富集程度有所差异,3-5月的沙尘、7-9月的降雨、11月农村农作物秸秆燃烧及冬季取暖燃煤等对水溶性离子都有一定影响,窟内PM2.5中游客数量与NH4+和NO^(3-)有一定的相关性(R2=0.27、0.35)、PM10~2.5中游客数量与NH4+有一定的相关性(R2=0.31);(4)沙尘天气下窟外和窟内的PM2.5与PM10-2.5中Cl-、SO_(4)^(2-)、Na^(+)、K+和Ca^(2+)的浓度增加,窟区微环境主要受区域环境气象因素影响,建议极端沙尘天气关闭洞窟;(5)莫高窟大气环境呈碱性;(6)PM2.5和PM10~2.5主要来源于当地秸秆燃烧、二次污染源、土壤沙尘及干涸的大泉河。

采用机器学习分割算法和扫描电镜分析页岩微观孔隙结构

以五峰-龙马溪组页岩样品为例,进行拼接扫描电镜(MAPS)和聚焦离子束扫描电镜(FIB-SEM)测试,建立样品二维和三维灰度图像,采用机器学习分割算法划分为孔隙、有机质、矿物骨架和黄铁矿。根据孔隙周围矿物类型和形状,将孔隙细分为有机孔、无机孔和微裂缝,并统计含量和孔径分布。结果表明与常规灰度阈值分割算法相比,该方法准确识别灰度异常区域的组分类型,实现孔径10~200 nm页岩孔隙的精确划分;受分辨率限制,SEM图像识别的页岩总孔隙度与有机质含量与实验结果存在差异。

Response laws of rock electrical property and saturation evaluation method of tight sandstone

To solve the problem that the law of rock electrical response under low and medium water saturation in tight sandstone reservoirs is not clear, an experimental method of high-speed centrifugal displacement rock electricity and nuclear magnetic resonance T2 spectrometry under different water saturation was proposed, which can drive the tight sandstone cores with the permeability less than 0.1×10^-3 μm^2, and provide a reliable experimental means for the study of tight sandstone electrical property. By carrying out supporting experiments such as high-resolution CT scan, MAPS and Qemscan, a multi-mineral component fine three-dimensional digital core based on multi-source information fusion was constructed. The finite element numerical simulation method was used to obtain the electrical response of tight sandstone core with low water saturation which cannot be obtained in laboratory conditions. By combining experiment and numerical simulation, the electrical response laws have been clear of tight sandstone with complex pore structure, and the saturation evaluation method of variable rock electrical parameters based on pore structure has been developed. The processing of logging data of multiple wells in tight sandstone reservoir of Chang 7 Member in the Ordos Basin shows that this method can obtain more accurate oil saturation, and provides a new idea and method for fine logging evaluation of tight sandstone reservoir.

Anisotropy interpretation and the coherence research between resistivity and acoustic anisotropy in tight sands

Aiming at the problem of anisotropy inversion of tight sands, a new method for extracting resistivity anisotropy from array laterolog and micro-resistivity scanning imaging logging is proposed, and also the consistency of electric and acoustic anisotropy is discussed. Array laterolog includes resistivity anisotropy information, but numerical simulation shows that drilling fluid invasion has the greatest influence on the response, followed by the relative dip angle θ and electrical anisotropy coefficient λ. A new inversion method to determine ri, Rxo, Rt and λ is developed with the given θ and initial values of invasion radius ri, flushed zone resistivity Rxo, in-situ formation resistivity Rt. Micro-resistivity image can also be used for describing the resistivity distribution information in different directions, and the electrical characteristics from micro-resistivity log in different azimuths, lateral and vertical, can be compared to extract electric anisotropy information. Directional arrangement of mineral particles in tight sands and fracture development are the intrinsic causes of anisotropy, which in turn brings about anisotropy in resistivity and acoustic velocity, so the resistivity anisotropy and acoustic velocity anisotropy are consistent in trends. Analysis of log data of several wells show that the electrical anisotropy and acoustic anisotropy extracted from array laterolog, micro-resistivity imaging and cross-dipole acoustic logs respectively are consistent in trend and magnitude, proving the inversion method is accurate and the anisotropies of different formation physical parameters caused by the intrinsic structure of tight sand reservoir are consistent. This research provides a new idea for evaluating anisotropy of tight sands.

一种陆相页岩油岩相测井定量识别方法

随着中国页岩油勘探开发进程的推进,页岩油已成为当前国内寻找油气资源的重要领域.纯页岩型页岩油作为陆相页岩油类型之一,与国内外其他盆地页岩油相比,其具有黏土含量高、岩石矿物成分复杂、纹层及页理异常发育等典型特点.为了深化页岩油储层岩相特征认识,笔者基于岩心精描、XRD全岩分析和测井新技术等多种资料,依据“岩石成分+沉积构造”的岩相划分方案,建立了古龙页岩油岩相测井识别方法,实现了页岩岩相的定量识别与表征.(1)构建青一段元素-矿物转换模型,准确计算岩石矿物成分,依据不同岩性测井响应差异,建立以元素测井为主,常规测井为辅的岩性识别方法,将青一段页岩划分为4类,即黏土质页岩、长英质页岩、介壳灰岩/白云岩和粉砂岩;(2)充分发挥电成像测井高分辨率特性,提出利用电成像测井单位窗长范围内微电极曲线平均极值变化数量化表征岩石沉积构造,不仅弥补了传统动静态图像和切片图像对毫米级纹层分辨能力不足的难题,而且实现了定量表征,提高了岩石沉积构造的识别精度;(3)基于岩石成分和沉积构造的相互耦合,结合研究区实际岩相特征,系统将古龙页岩划分为8种岩相类型,实现了古龙页岩油岩相测井定量表征方法,识别结果与岩心描述具有很好一致性,可为后续页岩油优势岩相分析提供技术支撑.

倾斜电各向异性地层阵列感应测井数据处理新方法

阵列感应测井的原始信号经软件聚焦算法处理后可提供多种分辨率、不同探测深度的电阻率信息,这使得阵列感应测井成为复杂油气层测井评价的重要手段。然而,当在深层致密储层和非常规储层等电各向异性储层中采用斜井进行钻探时,由于传统软件聚焦算法没有考虑地层倾斜及其电各向异性的影响,常规阵列感应测井输出结果的适用性受到极大挑战,其电阻率曲线常出现钻井液假侵入、曲线乱序等异常现象。针对这一问题,提出以未聚焦的原始电阻率为约束,在已知仪器与地层相对夹角和目的层电各向异性系数的前提下,通过建立层状地层模型,结合仪器的正演算法模拟电阻率响应特征并与实测电阻率曲线进行误差比较,不断修改模型以进行迭代循环计算,从而得到等效的水平电阻率和垂直电阻率阵列感应测井曲线。该方法有效地剔除了地层倾角及其电各向异性的影响,且进一步通过分辨率匹配处理可获得具有给定分辨率、能完全保留钻井液侵入特征的地层水平方向和垂直方向的阵列感应电阻率曲线,显著提高了复杂储层的电阻率测量精度和测井解释符合率。相关算法得到了理论模型和多口实际测井资料的验证。

受原油黏度影响的鄂尔多斯盆地油湿和水湿砂岩导电响应规律

为了明确原油黏度对油湿和水湿砂岩储层的电性影响规律和机理,选用鄂尔多斯盆地长庆油田原油(黏度约为90 mPa·s)和煤油配置原油(黏度约为1 mPa·s),针对油湿和水湿的中—低渗透延长组砂岩开展了岩电、核磁共振、扫描电镜等对比实验,从岩石物理角度探索了不同黏度原油对油湿和水湿砂岩导电响应规律的影响机理。研究结果表明:(1)不论原油黏度高低,相同饱和度下油湿岩心电阻率都明显高于水湿岩心;(2)原油黏度对水湿岩心的岩电响应特征影响较小,但对油湿岩心影响很大,即油湿岩心的电性曲线呈明显的分段特征,且原油黏度越大,分段性越明显;(3)造成油湿岩心电性差异的主要原因在于高黏度原油对孔隙结构的叠加影响。研究成果对于油湿储层的油层识别和饱和度模型建立具有一定指导意义。在实际的岩石物理实验中,要注意原油黏度对油湿岩心岩电响应规律的影响,选取与地下原油黏度相近的油品进行实验才能得到具有代表性的结果。