Characteristics of acoustic emissions induced by fluid front displacement in porous media
Characteristics of acoustic emissions induced by fluid front displacement in porous media
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DOI：
10.1029/2012wr012525
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发表时间：
2012-11-06
影响因子：
5.4
通讯作者：
Or, Dani
中科院分区：
文献类型：
--
作者：
Moebius, Franziska;Canone, Davide;Or, Dani
多孔介质中流体驱替的动力学通常会影响相捕获并塑造宏观输运特性，因此对于一系列自然和工程应用具有相当大的意义。位移前沿的宏观运动由许多突然的孔隙尺度侵入事件组成，这些事件涉及快速界面跳跃和重构，以及可检测为声发射（AE）的相关机械和界面能量释放。我们进行了系统的流体置换实验，并测量了不同尺寸玻璃珠组件内流体前沿通过（主要是排水）期间的相关 AE。结果表明与不同驱替过程相关的不同声学特征，反映了对多孔介质孔径、驱替流速和液体性质的依赖性。与锋面动力学相关的丰富的AE信号表现出AE事件的数量与其幅度之间的幂律关系，让人想起类似雪崩的入侵过程。除了孔隙快速排空或填充（海恩斯跳跃）发出的 AE 信号外，排水前沿后面的重新分布和界面重新配置以及颗粒重排等其他过程也可能产生 AE。不同介质和各种边界条件下的位移过程产生的特征声发射特征为远程检测多孔介质中的孔隙尺度流体界面动力学提供了希望，该动力学可能会影响宏观传输特性（例如，与相捕获有关）。
The dynamics of fluid displacement in porous media often affect phase entrapment and shape macroscopic transport properties and thus are of considerable interest for a range of natural and engineering applications. The macroscopic motion of a displacement front is composed of numerous abrupt pore-scale invasion events that involve rapid interfacial jumps and reconfigurations with associated mechanical and interfacial energy release detectable as acoustic emissions (AE). We conducted systematic experiments of fluid displacement and measured associated AE during passage of fluid fronts (primarily drainage) within assemblies of glass beads of different sizes. Results indicated distinct acoustic signatures associated with different displacement processes, reflecting dependency on porous media pore size, displacement flow rate, and liquid properties. The rich AE signals associated with front dynamics exhibited power law relationships between the number of AE events and their amplitudes, reminiscent of avalanche-like invasion processes. In addition to AE signals emanating from rapid emptying or filling of pores (Haines jumps), other processes such as redistribution and interfacial reconfigurations behind a drainage front and grain rearrangement may generate AE. Characteristic AE signatures generated by displacement processes in different media and under various boundary conditions offer a promise for remote detection of pore-scale fluid interfacial dynamics in porous media that may shape macroscopic transport properties (e. g., linked with phase entrapment).