Aquifer heterogeneity characterization with oscillatory pumping: Sensitivity analysis and imaging potential
Aquifer heterogeneity characterization with oscillatory pumping: Sensitivity analysis and imaging potential
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DOI：
10.1002/wrcr.20356
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发表时间：
2013-09-01
影响因子：
5.4
通讯作者：
Barrash, W.
中科院分区：
文献类型：
--
作者：
Cardiff, M.;Bakhos, T.;Barrash, W.
定期抽水试验，即在半个周期内抽取流体，然后重新注入，历来用于估计有效含水层特性。在这项工作中，我们提出了一种修改后的方法来定期抽水测试分析，其中一个使用几个周期性的不同频率的抽水信号作为刺激，并通过逆建模使用稳定的周期性模型配方的响应进行分析。我们把这种策略称为多频振荡液压成像。振荡泵送测试具有几个已经注意到的优点，包括在测试期间没有净水提取和通过信号处理进行鲁棒的信号测量。通过数值实验，我们证明了额外的明显优势，多频刺激，包括：（1）通过使用一个稳定的周期性的数值模型，大大降低了计算成本和（2）充分利用含水层的非均质性信息提供的响应在不同的频率。我们首先进行充分的非均质含水层的瞬态数值模拟，并表明，使用更快的稳定周期的波相量的非均质数值模型，得到了等效的结果。观测信号响应含水层非均质性的灵敏度推导出使用伴随状态为基础的方法，这表明，不同的频率刺激提供互补的信息。最后，我们提出了一个例子2-D应用程序中，正弦信号在多个频率被用作数据源，并反演获得估计含水层的异质性。这些分析表明，不同的非均质性信息，可以从不同的刺激频率，并从几个正弦抽水试验的数据可以快速反演使用稳定的周期性框架。
Periodic pumping tests, in which a fluid is extracted during half a period, then reinjected, have been used historically to estimate effective aquifer properties. In this work, we suggest a modified approach to periodic pumping test analysis in which one uses several periodic pumping signals of different frequencies as stimulation, and responses are analyzed through inverse modeling using a steady-periodic model formulation. We refer to this strategy as multifrequency oscillatory hydraulic imaging. Oscillating pumping tests have several advantages that have been noted, including no net water extraction during testing and robust signal measurement through signal processing. Through numerical experiments, we demonstrate additional distinct advantages that multifrequency stimulations have, including: (1) drastically reduced computational cost through use of a steady-periodic numerical model and (2) full utilization of the aquifer heterogeneity information provided by responses at different frequencies. We first perform fully transient numerical modeling for heterogeneous aquifers and show that equivalent results are obtained using a faster steady-periodic heterogeneous numerical model of the wave phasor. The sensitivities of observed signal response to aquifer heterogeneities are derived using an adjoint state-based approach, which shows that different frequency stimulations provide complementary information. Finally, we present an example 2-D application in which sinusoidal signals at multiple frequencies are used as a data source and are inverted to obtain estimates of aquifer heterogeneity. These analyses show the different heterogeneity information that can be obtained from different stimulation frequencies, and that data from several sinusoidal pumping tests can be rapidly inverted using the steady-periodic framework.