A travel time based hydraulic tomographic approach
A travel time based hydraulic tomographic approach
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DOI：
10.1029/2003wr002262
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发表时间：
2003-12-24
影响因子：
5.4
通讯作者：
Dietrich, P
中科院分区：
文献类型：
--
作者：
Brauchler, R;Liedl, R;Dietrich, P
水力层析成像是一种识别地下水力特性三维空间分布的方法。我们提出了一种层析成像的方法，提供了在层析阵列中进行的液压或气动测试的旅行时间的反演。反演是基于记录的瞬态压力曲线的峰值时间和所研究的系统的扩散率之间的关系。转换因子的开发使得能够反演除了瞬态曲线的峰值时间之外的进一步的旅行时间。由于曲线的早期旅行时间主要与优先流特征有关，而基于晚期旅行时间的反演反映了整体行为，因此可以假设不同的反演结果反映了整个系统的特性。通过比较不同的重建系统的解释，因此变得更加全面和可靠。此外，建议的液压层析成像方法的地震走时层析成像的相似性，使我们能够应用的反演算法，用于地震层析成像。因此，我们应用交错网格的方法，这使得细化网格导致更高的标称分辨率，从一组干扰测试安排在层析阵列的数据。试验是在实验室非饱和裂隙砂岩圆柱体中进行的。扩散率分布的三维重建被认为是高度可靠和强大的。特别是，映射裂缝的砂岩圆柱体与我们重建的扩散率分布相吻合。
Hydraulic tomography is a method to identify the three-dimensional spatial distribution of hydraulic properties in the subsurface. We propose a tomographic approach providing the inversion of travel times of hydraulic or pneumatic tests conducted in a tomographic array. The inversion is based on the relation between the peak time of a recorded transient pressure curve and the diffusivity of the investigated system. The development of a transformation factor enables the inversion of further travel times besides the peak time of a transient curve. As the early travel times of the curve are mainly related to preferential flow features while the inversion based on late travel times are reflecting an integral behavior, it can be assumed that the different inversion results reflect the properties of the overall system. By comparing the different reconstructions the system interpretation therefore becomes more comprehensive and reliable. Furthermore, the similarity of the proposed hydraulic tomographic approach to seismic travel time tomography allows us to apply the inversion algorithms which are used for seismic tomography. We therefore apply the method of staggered grids, which enables to refine the grid resulting in a higher nominal resolution, to data from a set of interference tests arranged in a tomographic array. The tests were conducted in an unsaturated fractured sandstone cylinder in the laboratory. The three-dimensional reconstructions of the diffusivity distribution are found to be highly reliable and robust. In particular, the mapped fracture of the sandstone cylinder coincides with our reconstructed diffusivity distribution.