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根据孔隙介质的动电耦合理论设计了一套岩芯渗透率测量系统.实验采用交流锁相放大技术,在低频12~42 Hz范围内完成了砂岩岩样流动电势和电渗实验,得到了流动电势系数KS和电渗压力系数KE,进而计算出岩样动电渗透率,对于中、高渗透率岩样,测量得出的动电渗透率与常规气测渗透率差异较小,两者具有很好的相关性.实验表明,动电测量可作为岩样渗透率测量的一种方法,同时揭示了利用地层动电测井信号反演地层参数的可能性,实验结果对于分析天然地震动电效应也有参考意义. 相似文献
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本文针对流体饱和孔隙介质的动电效应,在砂岩模型井中开展了动电测井实验研究.记录到渗透率不同模型中单极源动电测井的全波波形,清晰地观测到了伴随纵波、横波和斯通利波的动电转换信号,给出了本文实验条件下,动电测井全波中各分波的幅度,并通过电声比的大小说明了各分波的动电转换能力.实验结果表明:孔隙介质动电效应与渗透率密切相关,动电信号的幅度随着地层渗透率的增大而增加,在高渗透率地层中记录动电信号的幅度较大,这一特性可用于地层渗透率的井下动电评估.本文实验结果还验证了动电测井的可行性,同时指出:与声波测井相比,动电测井信号对地层渗透率更加敏感,这为渗透率等地层参数的井下动电测量奠定了实验基础. 相似文献
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动态渗透率和动电耦合系数是描述岩石中渗流波动和弹性-电磁耦合波效应的重要参数.本文基于毛细管束模型,提出了流体饱和孔隙介质的动态渗透率和动电耦合系数的解析表达式和简化表达式,并通过与前人近似式结果的对比,分析了不同表达式的合理性和适用性.在此基础上,理论分析了孔隙几何形状和孔径分布对渗透率和动电耦合系数的频率响应以及井孔震电耦合波场的影响.研究结果表明:当认为孔道均匀且达西渗透率、孔隙度和弯曲度恒定时,孔隙几何形状的影响很小,可以忽略,而前人的近似式高估了孔隙几何形状的影响;孔径分布的影响显著,随着孔径分布的增大,渗透率的临界频率显著减小,动电耦合系数的临界频率显著增加,震电测井的斯通利波及其伴随电场幅度显著增大. 相似文献
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连续测量岩心的流动电势效应和电渗效应,可以获得岩心的动电渗透率,并验证Onsager互易性.通常这两个实验的岩心夹持器需要使用不同的堵头,而更换堵头会导致岩心内流体的参数和边界条件发生变化.本文设计了新的岩心夹持器和激励压力源,避免了在测量过程中更换堵头,提高了两个实验的一致性.本文测量了蒸馏水、以及0.01、0.02、0.05、0.1、0.2、0.4和0.6mol/L氯化钠溶液饱和的10块岩心的流动电势效应和电渗效应,获得了动电渗透率,并验证了低矿化度下的Onsager互易性.结果表明,Onsager互易性在低矿化度下是成立的;对于高矿化度,电渗效应能够取代流动电势效应用于反演渗透率. 相似文献
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油水饱和泥质砂岩中流动电位的研究对于揭示含油储层震电勘探和动电测井的机理有着重要的意义.本文首先从岩石孔隙的微观结构出发,构造了描述水润湿条件下油水饱和泥质砂岩储层的毛管模型.在模型中依据油水流动遵守的Navier-Stokes方程和电化学传质动力学理论,建立了描述油水饱和泥质砂岩流动电位的数学方程,并数学模拟了岩石储渗参数对流动电位频散特性的影响规律.研究结果表明:储层孔隙内流体受到的粘滞力与惯性力控制着水相和油相的流动,从而决定了流动电位的频散特性.随着孔隙度的增大,油水两相各自的有效渗透率均增大;而含水饱和度的升高使得水相有效渗透率增大,油相有效渗透率减小.在水润湿条件下,流动电位耦合系数随含水饱和度升高而增大,随束缚水饱和度的升高而减小.另外,流动电位相对耦合系数也随含水饱和度的升高而增大,但无频散现象. 相似文献
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动电效应指孔隙介质中与固/液界面的双电层和孔隙流体渗流有关的弹性-电磁耦合现象,探索基于动电效应的勘探和测井新方法则是石油工业重点关注的研究方向之一.本文对流体饱和孔隙介质中的动电效应进行了实验测量研究,记录到了不同模型井中伴随声波的动电转换信号和界面动电转换信号,对比分析了这两种动电信号的产生条件及传播特性,验证了理论分析结果,并进一步研究了动电信号的分波成分及其与声波信号的关系,探讨了声源激发模式、电极接收方式及数据处理方法对动电信号的影响,为动电测井仪器设计奠定实验基础. 相似文献
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基于孔隙介质动电效应的测量方法在油气勘探领域有着巨大的潜在应用价值.本文针对理论预测的随钻动电测井可削弱钻铤波对地层声波干扰的问题,设计了室内随钻动电测井实验装置和测量系统,并在小尺寸砂岩模型井中开展了随钻动电测井实验研究.为了突出随钻动电测井技术的特点,本文先在砂岩模型井中进行了电缆声波测井和电缆动电测井实验测量,获得了地层声波的传播速度.然后又在同一模型井中进行了随钻声波测井和随钻动电测井实验,记录了这两种情况下的测井全波波形,比较了电缆声波/动电测井和随钻声波/动电测井的差异性,并进一步分析了钻铤波和井中动电转换信号的传播特性.本文还通过随钻动电测井的时域波形提取到被测地层的纵横波速度,从实验角度验证了随钻动电测井技术测量地层波速的可行性.此外,本文实验结果对随钻动电测井的仪器设计及现场测量也有参考意义. 相似文献
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探索基于孔隙介质动电效应的随钻测井新方法是当前测井勘探领域的热点研究之一.本文针对随钻测井情况下的动(声)-电转换机理,在砂岩模型井中进行了多极源(单/偶/四极源)随钻动电测井实验研究,记录了井中声波激发动电转换波场的时域波形,给出了各分波的时间-速度图,并与多极源随钻声波测井数据进行对比,结果表明:钻铤波诱导的动电转换信号在随钻动电测井全波中的相对幅度显著降低,从而可准确提取到地层声波的传播速度,实现了利用随钻动电测井方法测量地层波速的目的,验证了随钻动电测井技术可有效抑制钻铤波的思想.本文还进一步分析了钻铤波的动电耦合特性,并结合有机玻璃模型井中随钻动电测井和无井孔模型下的随钻声波测量,研究了伴随钻铤波电场信号的传播特性和衰减规律,深入探讨了随钻动电测井全波中钻铤波被削弱的原因,并给出了定量的实验数据分析,为随钻动电测井理论模拟的解释提供有效实验数据支撑. 相似文献
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利用储层岩石流动电位的频散特性评价复杂储层已经成为勘探地球物理领域关注的热点,但是目前还没有形成基于储层岩石储渗特性及电化学性质的具有普遍指导意义的理论方法和数学模型.本文利用微观毛管理论,通过随时间谐变条件下渗流场和电流场的耦合模型,建立了描述储层岩石流动电位频散特性的数学方法,定量分析了频率域储层岩石动态渗透率、动电耦合系数和流动电位耦合系数随储层岩石孔隙度、溶液浓度和阳离子交换量的变化规律.研究结果表明:储层岩石流动电位频散特性是储层流体惯性力与流体黏滞力相互作用的结果.储层岩石孔隙度越大,储层维持流体原有运动状态的能力越大,临界频率越小;储层岩石的溶液浓度和阳离子交换量对临界频率没有影响.储层岩石的孔隙度越大,流体流动能力越强,流动电位各耦合系数的数值越大;溶液浓度越小或阳离子交换量越大,孔隙固液界面的双电层作用越强,各耦合系数的数值越大. 相似文献
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本文研究声电效应测井波场的有限差分模拟算法.忽略井外地层中诱导电磁场对孔隙弹性波的影响,将求解动电耦合波方程组的问题解耦,先计算孔隙弹性波,再计算其诱导电磁场.基于轴对称柱坐标系下的速度-应力交错网格,采用时域有限差分计算井孔流体声波和井外地层孔隙弹性波.将电磁场近似看作似稳场,基于轴对称柱坐标系下的5点式有限差分网格,求解不同时刻的电位Poisson方程,计算诱导电场.结果表明:本文算法可准确模拟频率6.0 kHz的声电效应测井全波;在声波测井频率范围内,电导率、动电耦合系数和动态渗透率的低频近似对伴随电磁场的计算影响不大;地层水平界面导致伴随反射斯通利波的电场和显著的界面电磁波,后者对于探测地层界面具有潜在的应用价值. 相似文献
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Influence of water pressure dynamics and fluid flow on the streaming‐potential response for unsaturated conditions 
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下载免费PDF全文 V. Allègre L. Jouniaux F. Lehmann P. Sailhac R. Toussaint 《Geophysical Prospecting》2015,63(3):694-712
Streaming‐potentials are produced by electrokinetic effects in relation to fluid flow and are used for geophysical prospecting. The aim of this study is to model streaming potential measurements for unsaturated conditions using an empirical approach. A conceptual model is applied to streaming potential measurements obtained from two drainage experiments in sand. The streaming potential data presented here show a non‐monotonous behaviour with increasing water saturation, following a pattern that cannot be predicted by existing models. A model involving quasi‐static and dynamic components is proposed to reproduce the streaming potential measurements. The dynamic component is based on the first time derivative of the driving pore pressure. The influence of this component is investigated with respect to fluid velocity, which is very different between the two experiments. The results demonstrate that the dynamic component is predominant at the onset of drainage in experiments with the slowest water flow. On the other hand, its influence appears to vanish with increasing drainage velocity. Our results suggest that fluid flow and water distribution at the pore scale have an important influence on the streaming potential response for unsaturated conditions. We propose to explain this specific streaming potential response in terms of the behaviour of both rock/water interface and water/air interfaces created during desaturation processes. The water/air interfaces are negatively charged, as also observed in the case of water/rock interfaces. Both the surface area and the flow velocity across these interfaces are thought to contribute to the non‐monotonous behaviour of the streaming potential coefficient as well as the variations in its amplitude. The non‐monotonous behaviour of air/water interfaces created during the flow was highlighted as it was measured and modelled by studies published in the literature. The streaming potential coefficient can increase to about 10 to 40 when water saturation decreases. Such an increase is possible if the amount of water/air interfaces is increased in sufficient amount, which can be the case. 相似文献
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In theory, the streaming potential coefficient depends not only on the zeta potential but also on the permeability of the rocks that partially determines the surface conductivity of the rocks. However, in practice, it is hard to show the permeability dependence of streaming potential coefficients because of the variation of zeta potential from sample to sample. To study permeability dependence of streaming potential, including the effects of the variation of the zeta potential and surface conductance due to the difference in mineral compositions between samples, we perform measurements on 12 consolidated samples, including natural and artificial samples saturated with 7 different NaCl solutions to determine the streaming potential coefficients. The results have shown that the streaming potential coefficients strongly depend on the permeability of the samples for low fluid conductivity. When the fluid conductivity is larger than than 0.50 S/m for the natural samples or 0.25 S/m for the artificial ceramic samples, the streaming potential coefficient is independent of permeability. This behavior is quantitatively explained by a theoretical model. 相似文献
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We present transient streaming potential data collected during falling‐head permeameter tests performed on samples of two sands with different physical and chemical properties. The objective of the work is to estimate hydraulic conductivity (K) and the electrokinetic coupling coefficient (Cl) of the sand samples. A semi‐empirical model based on the falling‐head permeameter flow model and electrokinetic coupling is used to analyze the streaming potential data and to estimate K and Cl. The values of K estimated from head data are used to validate the streaming potential method. Estimates of K from streaming potential data closely match those obtained from the associated head data, with less than 10% deviation. The electrokinetic coupling coefficient was estimated from streaming potential vs. (1) time and (2) head data for both sands. The results indicate that, within limits of experimental error, the values of Cl estimated by the two methods are essentially the same. The results of this work demonstrate that a temporal record of the streaming potential response in falling‐head permeameter tests can be used to estimate both K and Cl. They further indicate the potential for using transient streaming potential data as a proxy for hydraulic head in hydrogeology applications. 相似文献