Laboratory testing of low-frequency strain measured by distributed acoustic sensing (DAS)
Laboratory testing of low-frequency strain measured by distributed acoustic sensing (DAS)
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DOI：
10.1190/segam2018-2997900.1
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
M. Becker;C. Ciervo;T. Coleman
中科院分区：
文献类型：
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作者：
M. Becker;C. Ciervo;T. Coleman
最近的现场实验表明，分布式声学传感 (DAS) 可用于记录 mHz 频率下的光缆应变。然而，光纤电缆结构对应变传递的影响尚未得到评估。这里介绍的实验室实验旨在模拟固定在与基岩裂缝相交的钻孔中的光缆。裂缝上的水应力预计会拉伸水泥钻孔，DAS 可以检测到这一点。在实验室中，我们将五种不同的光缆结构粘合到管道中，然后使用步进电机定期拉紧管道。用 DAS 测量应变。 DAS 测得的应变大小相差约两倍。这些结果是非常初步的，但证明了电缆结构对于解释低频应变测量的重要性
Recent field experiments have demonstrated that distributed acoustic sensing (DAS) can be used to record strain in fiber optic cable at mHz frequencies. However, the effect of fiber optic cable construction on strain transfer has not been evaluated. The laboratory experiments presented here were designed to mimic fiber optic cable cemented into a borehole that intersects bedrock fractures. Hydraulic stress on the fracture is expected to stretch the cemented borehole which can be sensed by DAS. In the laboratory, we cemented five different fiber optic cable constructions into a pipe and then strained the pipe periodically using stepper motors. Strain was measured with DAS. The magnitude of strain measured by DAS varied by about a factor of two. These results are very preliminary, but demonstrate the importance of cable construction on the interpretation of low-frequency strain measurements