Stochastic inversion of pneumatic cross-hole tests and barometric pressure fluctuations in heterogeneous unsaturated formations
Stochastic inversion of pneumatic cross-hole tests and barometric pressure fluctuations in heterogeneous unsaturated formations
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DOI：
10.1016/j.advwatres.2008.08.007
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发表时间：
2008-12-01
影响因子：
4.7
通讯作者：
Yeh, Tian-Chyi Jim
中科院分区：
文献类型：
--
作者：
Ni, Chuen-Fa;Yeh, Tian-Chyi Jim
渗透率和孔隙度的分布是控制非饱和地层中气流和气相运移的关键因素。为了了解此类地层中的流动和输运特性，表征方法是一种典型的方法，已被广泛应用于实验室和现场。正如大多数研究所认识到的那样，这种方法依赖于准确的测量，更重要的是，需要一个足够的工具来解释实验中的测量结果。本文提出了一种能够高分辨率估计非均质非饱和地层渗透率和孔隙度分布的气动反演模型。基于序贯线性估计器（SSLE）的概念，开发的模型占压缩性和密度的空气和估计的地质参数使用空气压力测量从顺序跨孔气动泵或注入测试。四个合成的例子，包括一个一维适定性，水平二维，和两个三维的问题，被用来评估开发的模型在非饱和地层中的渗透率和孔隙度的分布估计。数值试验的结果是有希望的。所开发的气动逆模型可以重建特性（即，渗透率和孔隙度）场。利用相对较少的可用测量数据，该模型可以准确地捕获非饱和地层的模式和估计属性的大小。两个复杂的三维例子的结果表明，所提出的模型可以使用少量的地下压力测量和估计k和phi在浅层土壤层利用大气压力的空间变化映射的裂缝连通性。(c)2008爱思唯尔有限公司保留所有权利。
The distributions of permeability and porosity are key factors that control airflow and gas phase transport in unsaturated formations. To understand the behavior of flow and transport in such formations, characterization procedure is a typical approach that has been widely applied to laboratories and fields. As is recognized by most investigations, this approach relies on accurate measurements, and more importantly, an adequate tool to interpret those measurements from experiments. This study presents a pneumatic inverse model that is capable to estimate the distributions of permeability (k) and porosity (phi) with high resolution in heterogeneous unsaturated formations. Based on the concept of sequential successive linear estimator (SSLE), the developed model accounts for compressibility and density of air and estimates the geologic parameters using air pressure measurements from sequential cross-hole pneumatic pumping or injection tests. Four synthetic examples, including a one-dimensional well-posed, a horizontally two-dimensional, and two three-dimensional problems, are used to evaluate the developed model in estimating the distributions of permeability and porosity in unsaturated formations. Results of the numerical experiments are promising. The developed pneumatic inverse model can reconstruct the property (i.e., permeability and porosity) fields if the well-defined conditions are met. With a relatively small number of available measurements, the proposed model can accurately capture the patterns and the magnitudes of estimated properties for unsaturated formations. Results of two complex three-dimensional examples show that the proposed model can map the fracture connectivity using a small number of subsurface pressure measurements and estimate k and phi in shallow soil layers using spatial variations of barometric pressure. (c) 2008 Elsevier Ltd. All rights reserved.