Investigation of gas content of organic-rich shale:A case study from Lower Permian shale in southern North China Basin,central China

Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality.Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit(ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit(MCF) method, based on the 'bidisperse' diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation(USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, the ACF and MCF methods, are the best options respectively.

A Quantitative Evaluation of Shale Gas Content in Different Occurrence States of the Longmaxi Formation: A New Insight from Well JY-A in the Fuling Shale Gas Field,Sichuan Basin

Comprehensive quantitative evaluation of shale gas content and the controlling factors in different occurrence states is of great significance for accurately assessing gas-bearing capacity and providing effective well-production strategies. A total of 122 core samples from well JY-A in the Fuling shale gas field were studied to reveal the characteristics of S_1 l shale,15 of which were selected to further predict the shale gas content in different occurrence states, which are dependent on geological factors in the thermal evolution process. Geological parameters were researched by a number of laboratory programs, and the factors influential in controlling shale gas content were extracted by both PCA and GRA methods and prediction models were confirmed by the BE method using SPSS software. Results reveal that the adsorbed gas content is mainly controlled by TOC, Ro, SSA, PD and pyrite content, and the free gas content is mainly controlled by S_2, quartz content, gas saturation and formation pressure for S_1 l in well JY-A. Three methods, including the on-site gas desorption method, the empirical formula method, and the multiple regression analysis method were used in combination to evaluate the shale gas capacity of well JY-A, all of which show that the overall shale gas content of well JY-A is in the range of 2.0–5.0 m^3/t and that the free gas ratio is about 50%, lower than that of well JY-1. Cause analysis further confirms the tectonics and preservation conditions of S_1 l in the geological processes, especially the influence of eastern boundary faults on well JY-A, as the fundamental reasons for the differences in shale gas enrichment in the Jiaoshiba area.

中国石化探区和邻区油页岩原位开采选区评价

中国石化探区油页岩资源丰富,是国家重要的战略储备资源和补充能源。加快油页岩勘探开发对改善中国能源结构和保障国家能源安全具有重要意义。为了实现油页岩规模勘探与效益开发,通过调研梳理国内外成功开展油页岩原位开采现场试验的技术,分析试验区特征、地质和工程适应性、选区选层要求等认为:国外壳牌公司电加热法技术、中国吉林众诚公司的原位压裂化学干馏技术和吉林大学的局部化学反应法原位裂解技术实施了现场先导试验并获得成功,但中国两项技术的成熟度和可行性有待进一步研究论证,且现有的原位开采技术对深部油页岩的适应性均未得到验证。通过开展油页岩原位开采技术特点、地质资源条件、开采工程条件梳理分析,针对约束中国油页岩原位开采的关键因素,结合加热方式确定了4项地质参数、6项工程参数和分级评价界限,并根据约束油页岩原位开采利用的程度确定各参数的权重,建立了油页岩原位开采有利区地质-工程双因素评价模型,优选出15个中国石化探区和邻区油页岩Ⅰ类有利区。对选出的有利区进一步分析其顶底板、断裂、可动水等关键因素的影响,并综合评价优选出4个试验目标区,分别为:鄂尔多斯盆地南缘旬邑区块、博格达山北麓南缘上黄山街含矿区、茂名盆地电白含矿区、抚顺盆地抚顺含矿区。

Microscopic oil occurrence in high-maturity lacustrine shales:Qingshankou Formation,Gulong Sag,Songliao Basin

Occurrence and mobility of shale oil are prerequisites for evaluating shale oil reserves and prioritizing exploration targets,particularly for heterogeneous lacustrine shales.The Qingshankou Formation in the Gulong Sag,Songliao Basin is a classic lacustrine pure shale reservoir that contains abundant shale oil resources.The predicted geological reserves of the shale are 1.268×10^(9) t.In this study,field emission scanning electron microscope(FE-SEM),the modular automated processing system(MAPS),pyrolysisgas chromatography(Py-GC),low-pressure nitrogen gas adsorption(LPNA),Soxhlet extraction,pyrolysis,and 2-D nuclear magnetic resonance(NMR)were integrated to describe the shale oil components,microscopic occurrence,mobility,and the effective pore size distribution.Meanwhile,the related controlling factors are discussed.The shale oil in the Qingshankou Fm exists dominantly in the matrix pores of the clay minerals,with small amounts distributed in the intergranular pores of terrigenous clastic grains,intercrystalline pores of pyrite,intragranular pores of ostracod shells,and micro-fractures.Shale oil is distributed in the pore spaces of variable sizes in different lithofacies.The clay mineral-laminated shales are characterized by the broadest range of pore size and largest volume of pore spaces with shale oil distribution,while the ostracod-laminated shales have limited pore spaces retaining oil.Furthermore,the proposed integrated analysis evaluates the shale oil molecules existing in two states:movable,and adsorbed oil,respectively.The result illustrates that movable oil takes up 30.6%e79.4%of the total residual oil.TOC,mineral composition,and pore structures of the shale joint together to control the states and mobility of the shale oil.TOC values are positively correlated with the quantities of shale oil regardless of the state of oil.The mineral components significantly impact the state of shale oil.Noticeable differences in the states of oil were observed following the changing types of minerals,possibly due to their difference in adsorption capacity and wettability.Clay minerals attract more adsorbed oil than movable oil.Felsic minerals generally decrease the occurrence of total and adsorbed oil.Carbonate plays a positive role in hydrocarbon retention of all the shale oil states.As for the pore structure,the average pore size exerts a critical impact on the total,movable,and adsorbed oil content.The total pore volume and specific surface area of shales play a principal role in controlling the total yields and amounts of adsorbed oil.This research improves the understanding of the occurrence characteristics and enrichment mechanisms of shale oil in terrestrial pure shales and provides a reference for locating favorable shale oil exploration areas.

Correction Method of Light Hydrocarbons Losing and Heavy Hydrocarbon Handling for Residual Hydrocarbon (S_1) from Shale

In China, hot researches on shale oil were raised by the important breakthrough of shale oil in America. Obviously, the first important issue is the actual shale oil resource potential of China, and the selection of the key appraisement parameter is vital to the shale oil resource amount. Among the appraisement parameters, the oil content parameter（S1） is the key one, but the evaluation result is generally lower because of light hydrocarbon losing and heavy hydrocarbon handling. And the more important thing is that the light hydrocarbon with small molecular weight is more recoverable, and therefore its amount is important to the total shale oil yields. Based on pyrolysis experiments and the kinetic model of hydrocarbon generation, correction factors and a model of light hydrocarbon losing and heavy hydrocarbon handling were established. The results show that the correction factor of heavy hydrocarbon handling is 3.2, and that of light hydrocarbon losing is controlled by kerogen type, maturity and hydrocarbon generation environment（closed or open）.

Discovery and Analysis of Shale Gas in a Carboniferous Reservoir and its Enrichment Characteristics in the Northern Nanpanjiang Depression, Guizhou Province, China

Shale gas resources are considered to be extremely abundant in southern China,which has dedicated considerable attention to shale gas exploration in recent years.Exploration of shale gas has considerably progressed and several breakthroughs have been made in China.However,shale gas explorations are still scarce.Summary and detailed analysis studies on black shale reservoirs are still to be performed for many areas.This lack of information slows the progress of shale gas explorations and results in low quantities of stored black shale.The Carboniferous Dawuba Formation,which is widely distributed and considerably thick,is one of the black shale formations targeted for shale gas exploration in southern China in the recent years.The acquisition and analysis of total organic carbon,vitrinite reflectance,types of organic matter,mineral composition,porosity,and permeability are basic but important processes.In addition,we analyzed the microscopic pores present in the shale.This study also showesd the good gas content of the Dawuba Formation,as well as the geological factors affecting its gas content and other characteristics.To understand the prospect of exploration,we compared this with other shale reservoirs which have been already successfully explored for gas.Our comparison showesd that those shale reservoirs have similar but not identical geological characteristics.

Economic feasibility and efficiency enhancement approaches for in situ upgrading of low-maturity organic-rich shale from an energy consumption ratio perspective

The technical feasibility of in situ upgrading technology to develop the enormous oil and gas resource potential in low-maturity shale is widely acknowledged.However,because of the large quantities of energy required to heat shale,its economic feasibility is still a matter of debate and has yet to be convincingly demonstrated quantitatively.Based on the energy conservation law,the energy acquisition of oil and gas generation and the energy consumption of organic matter cracking,shale heat-absorption,and surrounding rock heat dissipation during in situ heating were evaluated in this study.The energy consumption ratios for different conditions were determined,and the factors that influence them were analyzed.The results show that the energy consumption ratio increases rapidly with increasing total organic carbon(TOC)content.For oil-prone shales,the TOC content corresponding to an energy consumption ratio of 3 is approximately 4.2%.This indicates that shale with a high TOC content can be expected to reduce the project cost through large-scale operation,making the energy consumption ratio after consideration of the project cost greater than 1.In situ heating and upgrading technology can achieve economic benefits.The main methods for improving the economic feasibility by analyzing factors that influence the energy consumption ratio include the following:(1)exploring technologies that efficiently heat shale but reduce the heat dissipation of surrounding rocks,(2)exploring technologies for efficient transformation of organic matter into oil and gas,i.e.,exploring technologies with catalytic effects,or the capability to reduce in situ heating time,and(3)establishing a horizontal well deployment technology that comprehensively considers the energy consumption ratio,time cost,and engineering cost.

页岩含气量现场测试技术进展与发展趋势

含气量是页岩气勘探评价及生产决策中的关键性基础参数,大三段式现场含气量解吸是准确、经济、快捷的首选方法。有别于煤层气思路,页岩含气量在测试原理、方法、技术及仪器等方面均取得了重要进展。无管化测试技术和小三段式测量方法的提出和应用,在提高解吸气测试精度的同时提供了更多有价值的信息。从借鉴于煤层气的条件回推法到多点测量约束拟合法,页岩损失气测量方法更加摆脱了对假设条件的依赖。基于非接触式扭矩传递的方法原理,实现了残余气测试过程中的全程气密。双三段式的含气量准确测量,为总含气量、游吸比、可采系数等含气结构参数的分析和求取奠定了基础,但页岩的可采气量并不是损失气和解吸气的简单加和。高精度含气量现场解吸的应用领域广泛,高精度解吸数据的系统获得、含气结构多参数的预测评价、智能评价技术的实践应用等,是页岩含气量现场解吸发展的基本方向。

川东红星地区中上二叠统页岩气勘探成果及方向展望

基于构造、岩心、测井等资料,采用电镜扫描、低温N_(2)吸附实验、高压压汞实验、盆地模拟等手段,系统分析了川东红星地区中上二叠统页岩的沉积演化、储层特征及页岩气富集模式,明确了勘探有利区,总结了勘探成果及意义。研究结果表明:(1)红星地区中上二叠统的沉积演化表现为:栖霞组—茅口组三段为开阔台地相;茅四段底部为台地-陆棚相,相带变化快,茅四段顶部为斜坡-陆棚相,地层被剥蚀、南厚北薄;吴家坪组一段(吴一段)底部为海陆过渡滨岸沼泽-潟湖相,吴一段顶部为台地-斜坡-陆棚相,斜坡-陆棚相带分布范围小、相变快;吴二段为斜坡-陆棚相沉积,从早至晚依次受控于古气候、火山活动和古气候、火山活动,沉积中—晚期古生产力较高,TOC均值大于8.00%。(2)研究区茅四段及吴二段陆棚相区发育2套优质页岩,具有“高有机碳-高灰质”的特征,富有机质页岩厚度分别为19 m和25 m,孔隙类型以有机孔为主,结构以微孔和介孔为主;富碳凝灰岩薄夹层混合质页岩岩相、高碳凝灰岩薄夹层硅质页岩为优质岩相,孔隙度分别为6.27%和6.43%,TOC值分别为10.11%和9.35%,含气饱和度分别为92.59%和91.81%,脆性指数分别为55.24%和61.19%,是地质和工程的双“甜点”段。(3)研究区二叠系广泛发育的层状藻为主要有机质来源;在侏罗纪主排烃期,其构造稳定、二叠系烃源岩排烃较少,中侏罗纪—早白垩纪早期为主生气期,构造活动较弱,页岩气的保存条件好,现今已完成生气过程,处于成熟—过成熟阶段,Ro值约2.1%,勘探潜力巨大。(4)建南、龙驹坝、三星区块为有利勘探区,其中建南区块潜力最大;茅四段(3)小层及吴二段(3)小层为优质层系的靶窗层段。

不同构造单元页岩孔隙结构差异及其油气地质意义——以四川盆地泸州地区深层页岩为例

不同构造单元页岩储层品质、含气性差异明显,构造改造作用对页岩气勘探开发具有控制作用,但关于深层页岩气的构造控制作用机理研究较少,相关认识尚不明确,制约了深层页岩气的勘探开发。为此,通过“岩心—薄片—扫描电镜”多尺度观察、全岩矿物X射线衍射分析、核磁共振等技术手段,对比分析了四川盆地南部泸州地区不同构造单元上奥陶统五峰组—下志留统龙马溪组深层页岩孔隙结构和储层特征的差异,探讨了不同构造单元页岩孔隙结构差异与储层品质的耦合关系,明确了页岩气产量差异的内在地质原因,落实了构造改造作用下的页岩气勘探开发有利区。研究结果表明:①向斜区页岩主要以有机质孔隙、非构造裂缝为主,孔径大;背斜区页岩孔隙结构被强烈改造,以矿物粒间孔、构造裂缝为主,矿物粒间孔狭长且定向排列,孔径小。②向斜区构造相对稳定,有机质孔隙、矿物粒间孔以及成岩裂缝保存较好,宏孔占比高,储集性能好,含气量和产量高;背斜区页岩储层发育大量构造裂缝与断层,孔隙和成岩裂缝被压实,孔径减小,储集性能变差,含气量和产量低。③距盆缘剥蚀区越远,构造越稳定的单元,保存条件越好,该类构造单元页岩储层越发育,含气量和产量越高,页岩气勘探开发潜力越大。结论认为,构造运动对于压力系统的影响是形成不同构造单元深层页岩孔隙结构特征差异的重要因素,并控制了页岩储层的含气性与产量;向斜区深层保存条件好,远离剥蚀区,为勘探开发的最有利区,该认识可为深层页岩气勘探开发提供技术支撑。

中上扬子区海相页岩复电阻率响应特征及总有机碳含量预测

页岩的电性响应特征是评价页岩气储层总有机碳含量(TOC)的重要技术指标,而现有的TOC评价模型仅利用电阻率一个电性参数,不能满足储层评价的需要,复电阻率为此提供了新途径. 本文采用实验分析和理论建模的方法,以中上扬子区海相页岩为研究对象,通过对不同地区、不同地层及页岩气井的页岩进行复电阻率实验与模型研究,反演提取页岩的激发极化(IP)参数,揭示页岩有机质富集与复电阻率响应的内在联系及规律. 结合TOC测试结果,建立电阻率、极化率与TOC评价关系模型,发掘有利于页岩气储层评价的电性敏感参数,并应用于实际勘探试验区的储层TOC预测. 形成了一套以复电阻率参数测试为主的页岩储层岩石物性测试与分析的方法和技术,为应用电磁勘探方法进行页岩气储层TOC评价提供了理论基础和物性数据.

陆相页岩油甜点参数测井定量评价方法及应用

中国陆相页岩油储层按照沉积特征及生储组合关系分为夹层型、混积型和泥纹型3种类型,根据不同主控因素和面临的开发难点,可分为复杂构造影响型、储层强非均质型、高黏土难改造型、高黏油难流动型和低含油饱和度型5种类型。不同类型储层高产稳产的主控因素差异性大,甜点纵横向精细刻画、富集规律及展布特征是规模效益开发的关键。通过建立矿物组分、孔隙度、力学及脆性计算模型,结合直井试油和水平井生产动态资料,优选不同类型储层产能主控因素和核心参数,建立甜点分类评价标准,优选储层甜点段。综合分析表明,陆相页岩油优质甜点多为中、高TOC背景下,核磁大孔隙发育、页理缝有效性好(裂缝发育)的油气富集层,并具有良好顶板封盖条件。研究成果已经在多个油田的页岩油水平井靶窗优选和随钻跟踪中得到应用,可为页岩油勘探开发提供理论指导与技术支撑。

陆相页岩油储层可动油含量测井评价方法——以苏北盆地古近系阜宁组二段页岩油为例

近年来中国东部陆相盆地页岩油勘探开发取得重大进展,但制约页岩油产能评价的关键因素是油可动性。研究苏北盆地页岩油提出了二维核磁共振法和常规测井法2种测井评价页岩可动油含量的方法。建立了二维核磁共振测量纵向弛豫时间(T1)-横向弛豫时间(T2)可动油识别图版,评价吸附油及束缚水等流体类型,通过游离烃含量(S1)与沉积环境、沉积构造的关系及测井响应的关联性,分析常规测井电阻率及声波时差对游离烃含量、有机质含量响应灵敏度,建立了游离烃含量测井定量评价模型。提出了测井资料评价游离烃含量的方法,计算可动油饱和度及含油量。咸化环境和纹层状构造有利于有机质成烃和运移,游离烃含量高。

复兴区块陆相页岩压裂成缝特征与增产改造策略分析

复兴区块侏罗系纵向发育东岳庙段、凉高山组等多套陆相页岩,页岩油资源量10.54×108 t,页岩气资源量1.51×1012 m3,具有良好的立体勘探开发前景。该陆相页岩具有黏土矿物含量高、夹层发育、油气同出等特点,面临复杂成缝难度大、穿层扩体难度高、有效支撑需求高等一系列难题。文中通过各层段岩石力学特性和多因素作用下破裂成缝影响机理研究,揭示了东岳庙段、凉高山组页岩压裂成缝规律的共性和差异,明确了垂向地应力差、夹层性质、注入排量、压裂液黏度是影响裂缝延伸扩展的关键因素,提出了以“持续提净压、转向促复杂”为核心的压裂改造策略,制定了多簇密布缝、循环变排量、不同粒径支撑剂循环充填、高频复合暂堵等工艺优化的具体措施。现场应用后取得了单井改造效果和测试产能双突破。

多元线性回归模型与多层感知器神经网络在铀矿测井泥质含量预测中的应用

在铀矿资源勘探工作中,泥质含量的测定对于确定地下岩层的性质和砂岩型铀矿床的分布具有重要意义。文章旨在避免常规测井解释计算方法受到希尔奇系数选取准确性的限制,提出了利用多元线性回归模型和多层感知器(MLP,Multilayer Perceptron)神经网络对测井数据进行分析与预测的方法。通过选取某地区的测井数据,采用多元线性回归模型和MLP神经网络进行了泥质含量关系模型的构建和验证。结果显示,多元线性回归模型在泥质含量低层位出现过拟合现象,而MLP神经网络则表现出更高的预测准确性,MLP神经网络在泥质含量预测中优于传统多元线性回归模型,为铀矿勘探中泥质含量的准确预测提供了有效工具,并有望改进现有的泥质含量评价方法。这些研究成果可显著提升测井解释的效率和准确性,对后续铀矿勘探开发工作的开展具有积极影响。

基于Stacking算法集成学习的页岩油储层总有机碳含量评价方法

总有机碳含量(TOC)是页岩油储层评价的重要参数,而传统总有机碳含量测井评价方法精度较低且普适性较差,机器学习模型在一定程度上提高了总有机碳含量预测精度,但结果存在不稳定性。为了进一步提高页岩油储层总有机碳含量预测精度,基于有机质岩石物理特征和不同总有机碳含量测井响应特征的深入分析,优选出深侧向电阻率、声波时差、补偿中子和密度测井曲线作为总有机碳含量的敏感测井响应,并将其作为输入特征,以岩心分析总有机碳含量作为期望输出值,分别建立了决策树模型、支持向量回归机模型、BP(Back Propagation)神经网络模型,并建立了以决策树模型为基模型、支持向量回归机模型为元模型的Stacking算法集成学习模型。利用B油田A区块的岩心样本数据和实际井数据对不同模型预测总有机碳含量结果进行了验证,结果表明,基于Stacking算法的集成学习模型的总有机碳含量预测精度最高,相较于决策树模型、支持向量回归机模型、BP神经网络模型和改进的ΔlgR法,预测精度有较大提高。因此,基于Stacking算法的集成学习模型为该研究区最有效的总有机碳含量计算方法,这为准确地评估页岩油储层的生烃潜力、确保页岩油储层的高效开采及资源利用奠定了基础。

气体钻井岩屑含水量快速检测系统

针对目前钻井现场检测地层出水的方法速度慢、抗干扰能力弱的问题,利用近红外光在水中具有显著的吸收特性,提出了一种基于近红外图像的岩屑含水量快速检测系统。系统利用940 nm波段的近红外摄像头采集图像,消除可见光干扰,提高了检测的灵敏度。借助基于小波变换的滤波算法有效去除图像中的散射噪声,并采用区域生长算法进行图像分割,排除干扰物,避免误分割情况,提升系统的抗干扰能力。此外,运用HDBSCAN聚类算法快速精确提取岩屑区域,获取岩屑图像的灰度平均值。最后,利用分段线性回归算法构建了灰度值-含水量模型,预测岩屑含水量。实验结果表明:系统在复杂的天然气钻井环境中工作有效,最大绝对误差为1.87%,精度较高。平均检测时间不超过6 s,速度较快。相较于烘干法,系统在保证准确率的基础上显著提高了检测速度。与湿度传感器相比,系统不仅具有更高的检测精度,还能覆盖更大面积岩屑的水分检测需求。

基于质量含油率的湖相页岩油可动资源评价——以渤海湾盆地沧东凹陷孔二段为例

页岩样品中普遍存在烃类散失和有机质吸附,导致页岩油可动资源评价不准,为解决该难题,利用中国渤海湾盆地沧东凹陷孔二段G19-25井45 m密闭取心,创新设计了45块次3类(0 h与24 h、密闭与开放、常规与多温阶)页岩热解对比实验和12块次干酪根溶胀实验,构建了轻烃恢复校正系数和有机质吸附系数.研究表明,样品放置24 h后轻烃平均损失率为29.4%,开放条件下碎样轻烃平均损失率为21.0%,常规热解轻烃平均损失率为15.5%,综合平均损失率为47.1%,即原始地层状态下页岩滞留烃量是常规热解游离烃量的2倍(页岩油轻烃校正系数为2.0);页岩中单位有机质吸附烃量随着镜质体反射率Ro增加而逐渐降低,当Ro为0.8%~1.1%时,页岩有机质吸附油量平均为0.1(质量分数).本研究创建页岩油可动资源评价的质量含油率新方法,提出用页岩质量含油率表征页岩滞留烃去除有机质吸附烃后的页岩中可动烃量,评价孔二段页岩油可动资源量为6.8×10^(8)t,研究成果可为类似盆地页岩油研究提供借鉴.

含油率影响下油页岩力学性质与破坏断裂特征研究

油页岩的含油率存在巨大差异,这种含油率的变化会引起其力学性质与破坏断裂特征的差异。选取含油率为6.5%、6%、5%和3%的垂直层理油页岩试样,对其开展单轴压缩实验、场应变与声发射监测。研究发现:含油率的提升会降低油页岩抗压强度,并使其由脆性向延性转变。高含油率油页岩易发生剪切—张拉破坏;低含油率油页岩破坏模式偏向于张拉破坏。加载过程中,油页岩试件主应变场由均匀分布向应变集中分布转变,垂直层理油页岩的应变场更容易形成多条平行应变集中条带,当含油率不断降低时,主应变场变化过程中的剪切现象减弱。高含油率的试样振铃计数表现为阶梯型增长,破坏后,依然出现了较高的振铃计数;低含油率油页岩只在破坏时出现较高的振铃计数。相同弹性能条件下,低含油率油页岩在储能阶段的变形更小。高含油率试样具有一定延性,在试样到达应力峰值点后,弹性能并没有完全释放,仍保留一部分弹性能。低含油率试样的抗变形能力较强,所以,在相同应变条件下,其耗散的能量更高。

基于测井资料评价煤层气井产水

在煤层气开发过程中,产气量往往受产水量影响,多数高产水的井产能较低。产水量控制压降波及范围和甲烷解吸面积的大小,从而决定单井气产量高低和稳产期长短,因此准确地预测产水量就显得至关重要。根据排采过程中日产水量变化情况以及曲线形态分析,将研究区日产水量曲线分为单峰衰减型、稳产型和多峰型。不同产水类型的煤层具有不同的测井响应特征和顶底板封隔性。基于反映产水类型的关键测井参数以及顶底板封隔性的泥质含量,建立Fisher判别方程来确定产水类型。在测井资料与动态产水资料的综合研究基础上,建立不同产水类型的产水量计算方法,利用该方法计算的煤层产水量与实际产水量的吻合率在80%以上,为今后煤层的勘探开发提供了一定的技术理论基础。