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1.
在岩石力学试验研究中,常常需要精确制备不同含水率的岩石试验样品,而目前的方法尚难以保证所需的精度。为此,提出一种精确制备不同含水率岩石试样的方法,其基本原理是将欲制备的岩石试件烘干或饱水后放置于恒湿环境中,烘干样或饱和样会逐步吸湿或去湿而增加或减小重量,其含水率逐步增加或减小,直至稳定,最终得到稳定、均匀、含水率各异的试验样品,而其中的关键是如何获得一个稳定的恒湿环境。基于化学热力学中单组分的气-液平衡理论,提出了一种稳定恒湿环境的获取方法,其基本原理为：由于岩石中组分水的化学势与恒湿环境中的水气的组分水的化学势在起始阶段不相等,因此,二者中的水气压力也不同,必然有组分水的迁移;当岩石中的水气压力大于恒湿环境中的水气压力时,水便从岩石中迁移至恒湿环境中,使岩石失水,而当岩石中的水气压力小于恒湿环境中的水气压力时,水自恒湿环境中迁移至岩石中,使其含水率增加,直至二者中的水气压力平衡,即可得到某一特定含水率的岩石样品。这样制备的岩石样品满足化学热力学平衡的要求,其含水率内外一致,上下相同,是含水率均匀分布的合格样品。该方法还能制备其他方法无法实现的含水率相差甚微的岩石试件,也可直接应用于精确制备不同含水率的土样。 相似文献
2.
不同驱替方式下岩石电阻率与饱和度的关系 总被引：7，自引：0，他引：7
针对高含水期老区调整井饱和度评价过程中存在的问题,通过模拟油田开发过程的岩石物理实验,研究水驱油方式下电阻率与含水饱和度之间的关系。与油驱水不同,水驱油方式下电阻增大率与含水饱和度在双对数坐标系中的关系不再是一条直线,而呈现出明显的与高、低含水饱和度区间相关的两段式;岩石的润湿特征不同,两段式拐点所对应的含水饱和度Swp不同,水驱方式下所能达到的最终采收率也不同。水驱油方式下的I－Sw曲线特征表明,用勘探阶段及开发初期油驱水实验得到的饱和度公式对开发中后期的饱和度进行评价不太合适,尤其是在高含水期,电阻率对高含水饱和度反映能力的局限性严重制约了这一阶段水淹层的评价精度。 相似文献
3.
氧逸度是定量表示一个体系氧化还原能力的指标，反映了体系中氧气的分压或者逃逸能力。在地球科学中，它反映了岩石和矿物中变价元素的氧化还原状态，指示了不同岩石矿物氧化性/还原性的相对强弱。相同岩石矿物不同氧逸度可以导致其物理化学性质发生大的改变，因此在实验地球科学中准确控制并监测高温高压实验条件下的氧逸度具有非常重要的意义。本文从实验技术角度出发，首先介绍了活塞圆筒和多面砧高压装置中利用双胶囊技术在不含水和含水体系中控制氧逸度的方法、原理、装置和注意事项；接着描述了用过渡金属合金固溶体和惰性金属合金作为氧传感器原位测量氧逸度的原理、注意事项和地质应用，然后展示了氧离子固体电解质法控制和监测氧逸度的原理、装置和局限，提出了可能的改进方法。目前由于技术限制，氧逸度在高压实验中的控制和监测方法还不成熟，导致其对矿物和岩石物理化学性质的影响极可能被低估甚至错估。因此积极研究发展并推动高压下氧逸度的控制和监测技术非常重要且必要。 相似文献
4.
页岩气藏超低含水饱和度形成模拟及其意义 总被引：1，自引：0，他引：1
页岩气属于非常规天然气,资源丰富,开发潜力巨大。含水饱和度是控制致密气藏持续生产最关键的储层参数,然而现阶段对页岩气成藏中超低含水饱和度是否存在尚存在疑问。选取川渝地区页岩露头岩样,采用气驱法模拟了成藏过程中含水饱和度变化,结合川南页岩气储层地质特征,建立了生烃排驱的地质模型,提出了气携液的概念模型。结果表明,页岩气藏存在超低含水饱和度现象;页岩气成藏过程中大量生烃产生排驱效应与气携液作用,有利于页岩气储层超低含水饱和度的形成,气携液作用、裂缝和高温环境加速了含水饱和度降低;超低含水饱和度增加页岩气储层吸附能力,增大储层可流动孔喉范围,提高气相传输能力,但在工程作业过程中加大水相渗吸速率,强化水相滞留效应,使页岩气藏水相圈闭损害潜力更大。在页岩气有利区评价、气藏钻完井、开发过程中,须倍加重视超低含水饱和度这一客观事实和其衍生的工程作业问题。 相似文献
5.
液氮冻结条件下岩石孔隙结构损伤试验研究 总被引：2，自引：0，他引：2
液氮温度极低,约在-195.56-180.44℃之间,当与岩石接触时会对岩石孔隙结构产生损伤。根据这一特点,低温液氮有望作为压裂流体对储层进行压裂改造。为了研究液氮冻结对岩石孔隙结构损伤的影响,选取两种不同砂岩岩样,分别在不同初始含水饱和度条件下进行液氮冻结处理。对冻结前、后的岩样进行孔隙度以及核磁共振测试,得到岩样在冻结前、后的孔隙度、横向弛豫时间T2分布以及T2谱面积变化情况。试验结果表明:液氮冻结会对岩石的孔隙结构产生损伤,损伤程度受到岩性、孔隙度和岩石含水饱和度等因素影响;岩石含水饱和度越大,损伤就越严重,当岩石含水饱和度达到100%时,岩石表面产生了明显裂纹;岩石在液氮冻结下损伤形式主要是微孔隙的发育和扩展,微孔隙的增加会使岩石孔隙结构的连通性增强,甚至会产生新的大尺寸孔隙,从而对孔隙结构造成严重损伤。 相似文献
6.
珠江口盆地的低阻油层具有高泥质含量、低电阻率以及低产能的特点, 其真实含油饱和度的确定存在很大的困难。首先分析了区域低阻油层的地质成因, 指出地层束缚水含量高, 以及由此形成的发达的导电网络是导致油层低阻的主要原因;在此基础上, 利用多种适合于泥质砂岩地层的饱和度模型进行计算, 并根据密闭取心资料, 重点分析了在不同地层条件下, 对岩样含油、水饱和度进行脱气校正、压实校正、体积系数校正以及漏失校正的方法;并结合核磁共振测井, 对测井计算的含水饱和度进行标定。结果显示, 低阻油层的含水饱和度平均在70%以上, 且印度尼西亚公式计算的含水饱和度与岩心校正后的饱和度以及核磁束缚水饱和度吻合均很好, 因此印度尼西亚公式是最适合本区域低阻油层的饱和度评价模型。 相似文献
7.
致密砂岩的形成机制及其地质意义——以塔里木盆地英南2井为例 总被引：7，自引：0，他引：7
砂质岩的孔隙和喉道被网格状粘土矿物和次生加大矿物充填成微细孔喉状结构时,形成具有较高毛细管压力的致密砂岩。它与地层水发生水锁效应,可大大降低渗透率,成为致密砂岩盖层。当含水饱和度在50%以下时,束缚水饱和度比较低,致密砂岩储层可以产气;当含水饱和度在50%～90%区间时,具有较高的束缚水饱和度,相对渗透率非常低,它既不能产气也不能产水,反映为渗透率瓶颈区(具有盖层性质);当含水饱和度大于90%以上时,致密砂岩储层仅微量产水。塔里木盆地英南2井侏罗系气藏盖层由致密砂岩构成,不含水时的气体渗透率在(0.027～0.081)×10-3μm2,不能构成封堵;当含水饱和度达到60%以上时,相对渗透率几乎为零,构成有效盖层。 相似文献
8.
《海相油气地质》2015,(4)
中东YL-DS油田高含泥质灰岩储层(泥质含量3%~8%)电阻率低,常规解释的含水饱和度较高,按纯灰岩储层段流体评价标准常被判定为水层。本研究避开对难以量化表征的纯灰岩骨架中束缚水的直接求取,通过计算储层中的泥质束缚水孔隙度来直接校正常规含水饱和度,简单易行,在实践中取得了良好的效果。具体方法为:根据纯泥岩的简化模型计算纯泥岩孔隙度,然后采用能谱测井资料计算干黏土的密度值,计算泥质灰岩储层中的泥质束缚水孔隙度,对常规阿尔奇公式计算的水饱和度进行泥质束缚水饱和度校正而获得视纯灰岩含水饱和度,最后采用校正后的含水饱和度和纯灰岩段标准解释图版综合判断储层流体性质。 相似文献
9.
本文对含水矿物电子探针定量分析方法进行探讨,提出了从除水外各组分测定的和值中推算含水量并将其水量参与各组分浓度的校正计算。此法简便易行,提高了含水矿物定量分析的准确度,特别是对富含水矿物尤其重要。此外,本文对不稳定含水矿物的测试方法也作了一些研究。 相似文献
10.
沉积物与流体流动的性质是影响水合物形成和聚集的两个重要因素,为研究水合物在沉积地层中的赋存机制必须探明高压环境下含水合物沉积物在非饱和渗流条件下的相互影响关系。以逸度差为水合物反应驱动力,反应动力学常数为Arrhenius类型,建立了包括非饱和流体流动-沉积物特征-水合物形成动力学耦合的二维模型,从理论上研究了多孔介质内流体与沉积物参数如含水率、去饱和系数、水力分布和水合物饱和度等在孔隙内的相互影响规律。结果表明,在设定的条件下,随着反应的进行孔隙水压力随时间逐渐大,在相同条件下水合物饱和度与温度增加导致孔隙水压力变大,其中水合物饱和度的影响较小,而沉积物基质吸力、去饱和系数与本征动力学常数则与孔隙水压力成反向变化,其中本征动力学常数的影响较大。 相似文献
11.
以金沙江寨子村昔格达组半成岩为研究对象,通过X射线衍射、电镜扫描,测定了矿物成分、天然与饱和状态矿物颗粒微观结构;通过三轴压缩试验,研究了昔格达组半成岩受水和围压影响的强度及变形变化规律,并探讨了微观机制;通过对昔格达组半成岩、土、软岩强度指标与含水率的关系进行统计,分析了昔格达组半成岩不同于土和软岩的强度特性,并给出了针对此类岩土体的工程分级建议。研究表明：（1）微观结构显示昔格达组半成岩有明显不同于土和岩石的弱胶结结构特征,在饱和后胶结结构易遭破坏;（2）昔格达组半成岩黏聚力、摩擦角均随含水率增加而减小,平均模量在高含水率下随围压增加而增大,围压一定时随含水率增加而减小;（3）昔格达组半成岩、土、软岩的黏聚力大小为软岩>昔格达组半成岩>土,黏聚力对含水率的敏感性为软岩>昔格达组半成岩>土,摩擦角对含水率的敏感性为土>昔格达组半成岩>软岩;（4）将Φ50 mm×100 mm标准试件的单轴抗压强度在0.2～3 MPa,黏聚力在30～200 kPa的岩土体归类为硬土?软岩,建议在工程实际应用中将其与岩石和土进行区分。 相似文献
12.
利用真三轴岩爆试验系统,开展了不同饱水度红色粗晶花岗岩的岩爆试验,分析了不同饱水度下岩爆破坏岩样的强度与变形特征、破坏与弹射特征、声发射特性等,探讨了岩石饱水度与岩爆弹射动能的定量关系以及水对岩爆的影响机制。研究结果表明：（1）当岩样的相对饱水度超过0.3,其峰值应力和屈服应力较天然状态的明显降低;（2）岩样饱水度的增加使得岩爆过程中小颗粒弹射减少、小岩片剥落增多、岩板外鼓现象减弱,且岩爆坑体积减小、岩爆碎块的粒径分布由连续分布变为不连续分布;（3）随饱水度的增加,岩爆发生前夕声发射撞击数显著下降的平静期的总历时呈缩短趋势,岩爆发生时刻的声发射撞击数呈增大趋势,且累积绝对能量呈减小趋势、能量释放速度呈放缓趋势,表明岩样塑性破坏特性有所增强;（4）岩爆弹射动能随饱水度的增大而显著减小,二者呈单调线性的负相关关系,水对岩石的作用主要是软化和水楔作用,水的黏性也会对碎块弹射产生影响。 相似文献
13.
Y?lmaz Mahmuto?lu 《Engineering Geology》2006,82(3):137-144
It is well known rock masses contain several types of weakness planes varying from micro-fissure to fault in size. The fracture frequency, degree of saturation and time are the basic rock parameters affecting its behaviour. However, in most cases, it is practically difficult to test heavily fractured rock in laboratory environment. In this study, the effects of micro cracks, strain rate and water saturation on strength are discussed using a small-scale physical experiments. It is attempted to detach the grain boundaries of coarse-grained rock specimens of the Mu?la marble by thermal treatment that would serve as a small-scale physical simulation of fractures in rock masses and enable a discussion of the variations in time dependent mechanical behaviour. An experimental study was conducted on marble specimens induced thermally by micro-cracks in different frequencies. The thermal treatment periods being 24 h in inert atmospheric condition were varied for each test specimen except categories A and G. Effective porosity increased up to 2.4% after the last thermal cycle of category F. Then conventional compression tests with different strain rates were carried out using a servo-controlled testing machine on both dry and saturated specimens. It is concluded that both lowering strain rates and increasing porosity related with thermally induced micro cracks have important effects on strength and failure path. The progressive failure entirely occurs along the grain boundaries fissured by cyclical treatment and inter-granular deformation depends upon degree of thermal influence. The small-scaled laboratory model enabled to demonstrate that parameters such as joint frequency, time and saturation have a significant effect on mechanical behaviour of rock masses. 相似文献
14.
XIN-PING WANG YAN-XIA PAN RUI HU YA-FENG ZHANG HAO ZHANG 《Journal of Earth System Science》2014,123(2):297-305
Characteristics of water vapour condensation, including the onset, duration, and amount of water vapour condensation on moss-dominated biological soil crust (BSC) and dune sand were studied under simulated conditions with varying air temperature and relative humidity. The simulations were performed in a plant growth chamber using an electronic balance recording the weight of condensation. There was a positive linear correlation between the water vapour condensation and relative humidity while the mean temperature was negatively linearly related to amounts of water vapour condensation for both soil surfaces. The amount of water vapour condensation on BSC and dune sand can be described by the difference between air temperature and dew point with an exponential function, indicating that when the difference of air temperature and dew point exceeds a value of 35.3?C, there will be zero water vapour condensed on BSC. In contrast, when the difference of air temperature and dew point exceeds a value of 20.4?C, the water vapour condensation will be zero for dune sand. In general, when the air is fully saturated with water and the dew point is equal to the current air temperature, the water vapour condensed on BSC attained its maximum value of 0.398 mm, whereas it was 0.058 mm for dune sand. In comparison, water vapour condensed on BSC was at a relatively high temperature and low relative humidity, while we did not detect water vapour condensation on the dune sand under the similar conditions. Physical and chemical analyses of the samples pointed to a greater porosity, high content of fine particles, and high salinity for BSC compared to the dune sand. These results highlight that soil physicochemical properties are the likely factors influencing the mechanism of water vapour condensation under specific meteorological conditions, as onset was earlier and the duration was longer for water vapour condensation on BSC in comparison with that of dune sand. This contributed to the greater amount of vapour absorbed on BSC compared to the dune sand under an identical meteorological condition. The feedback of water vapour condensation on BSC formation and its contribution to sustain the revegetation desert ecosystems was discussed. 相似文献
15.
为研究石膏岩的水致老化效应,在室内模拟石膏矿采空区的水环境条件,包括不同空气湿度环境和饱和地下水环境。将石膏岩岩样置于其中,定期取出测定其力学性质指标,得到石膏岩老化的宏观力学表现,并结合核磁共振技术测定试验过程中石膏岩岩样内部的孔隙结构变化,分析石膏岩的水致老化机制。研究结果表明,水对石膏岩的老化效应具有显著的影响。老化程度随时间递增,石膏岩的单轴抗压强度、巴西抗拉强度和弹性模量与置于水环境中的时间基本呈负指数关系,泊松比则无明显变化规律;石膏岩老化程度和老化速率与水的状态密切相关。相对湿度越高,石膏岩的老化越显著,老化速率也更快,尤其是被液态水浸泡时,石膏岩的老化最显著,老化速率最快。水对石膏岩的老化过程是水的物理作用与化学作用的耦合,而化学作用是水致石膏岩老化的根本原因。石膏岩与水接触时,石膏的溶解、重结晶作用的不断进行改变着石膏岩的矿物组成结构,使其结构由紧密变得松散,孔隙率增大,力学性质不断弱化。该试验研究结果可为石膏矿开采的设计及采后空区的长期稳定性评估提供参考。 相似文献
16.
17.
为了研究含水状态下泥质粉砂岩的动态力学性能,进行了不同冲击速度下的分离式霍普金森压杆动载试验,重点研究泥质粉砂岩动力冲击过程中的能量耗散特征。结果表明:加载速率及含水率的变化将对岩样破坏均产生较大的影响。含水率的变化对岩样能量耗散特征产生较大影响,冲击速率越高时,试件的应变率越高,含水率越大时,比能量值及破碎程度也越高,平均破碎块度d越小;含水率的变化是导致断裂韧度变化的重要影响因素,含水率增加将导致试件的断裂韧度降低,在相同的冲击荷载下更容易断裂成碎块。 相似文献
18.
北淮阳金寨—苏仙石地区中生代花岗岩的成因类型及岩浆演化特征 总被引：2，自引：1，他引：1
摘 要 北淮阳金寨—苏仙石地区中生代侵入岩出露面积约150km 2 按岩石谱系单位的划
分原则可分为3个超单元（包括10个单元）和3个独立单元。根据主要造岩矿物及副矿物组
合、岩石化学和地球化学特征判别结果岩体成因类型以 I 型为主少数为 A 型和 S 型。岩
浆来源约30km 深处相当于下地壳或壳幔过渡部位。岩体形成深度约3～4km压力约0∙1
～0∙2GPa。形成温度约866～1150℃氧逸度 log f O
2 平均为—10∙97。进一步讨论了岩浆的
水逸度、水压及岩浆密度、岩浆演化和侵入岩与火山岩的成因关系。 相似文献
19.
At present,artificial freezing method has become one of the effective methods for coal mine shaft to pass through water-rich soft rock strata,which can stop the movement of groundwater and limit the deformation of surrounding rock. In order to study the frost heaving characteristics of sandstone under different freezing conditions,frost heaving tests of saturated and dry Cretaceous red sandstone samples under different freezing rates （10 ℃·h-1,5 ℃·h-1,2 ℃·h-1,1 ℃·h-1）and different confining pressures（5 MPa,10 MPa,15 MPa,20 MPa,25 MPa）were carried out by using GCTS（Geotechnical Consulting & Testing Systems）servo-controlled low temperature and high pressure triaxial rock testing system. In this paper,based on the existing theory of physical and mechanical properties of frozen soil,we studied the frost heaving law of sandstone under different freezing conditions and explored the frost heaving mechanism. The result shows that in the process of cooling,the dry rock sample always produce cold shrinkage deformation,while the saturated rock sample first produce cold shrinkage deformation,then produce frost deformation,and finally the deformation tends to be stable. The deformation of saturated rock samples is much larger than that of dry rock samples. The larger the stress level of rock samples at the same temperature is,the smaller the frost deformation is,which shows a linear negative correlation,mainly because the high confining pressure limits the volume expansion of the water phase in the pore inside the rock samples when it becomes ice. The frost deformation of rock samples is mainly affected by confining pressure and water content,while the frost heaving rate is mainly affected by cooling rate. Under this test condition,the higher the cooling rate of sandstone is,the higher the frost heaving rate is,and the relationship between them is approximately linear. For saturated rock samples,the confining pressure reduces the rock frost heaving by limiting the expansion during the phase transformation of ice water,and the temperature affects the rock frost heaving by affecting the freezing rate of pore water and the thermal expansion and cold contraction of rock skeleton. For dry rock samples,the deformation is mainly due to the volume contraction of rock mineral particles caused by thermal expansion and cold contraction effect,and the greater the temperature change,the greater the deformation. Based on the experimental results and theoretical analysis method,a calculation formula of rock frost heaving considering the influence of confining pressure was established. By calculating the frost heave of sandstone samples under different confining pressures,it is found that the calculated values are in good agreement with the experimental results. Moreover,according to the calculation formula of frost heaving,the influence factors of rock frost heaving during freezing can be divided into two categories：internal cause and external cause. The internal cause includes porosity,saturation,volume modulus of ice and rock skeleton,and the external cause includes temperature and confining pressure. For saturated rock,the frost heaving is mainly affected by factors such as confining pressure,temperature and porosity. When the saturation,porosity and freezing rate are low,the rock may only produce shrinkage deformation,because these indicators determine whether the rock produces frost heave or freeze shrinkage. The mechanism of rock frost heaving is very complicated due to the interaction and restriction between the internal and external factors and the dynamic changes of rock micro-structure and mechanical properties during the process of frost heaving. The research results can provide theoretical reference for freezing construction scheme design of deep coal seam mine construction,and also provide a theoretical basis for the study of physical and mechanical properties and engineering application of soft rock in frozen soil area. © 2022 Science Press (China). 相似文献