A comprehensive study of parameter determination in a joint MRS and TEM data analysis scheme
A comprehensive study of parameter determination in a joint MRS and TEM data analysis scheme
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DOI：
10.3997/1873-0604.2013040
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发表时间：
2013-10
影响因子：
1.6
通讯作者：
A. Behroozmand;E. Dalgaard;A. Christiansen;E. Auken
中科院分区：
文献类型：
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作者：
A. Behroozmand;E. Dalgaard;A. Christiansen;E. Auken
我们提出了一个全面的研究联合MRS和瞬变电磁（TEM）数据分析方案中的磁共振测深（MRS）模型的参数确定。通过基于后验模型协方差矩阵计算模型参数不确定性来评估参数确定。一个完整的MRS数据集，依赖于脉冲时刻和时间门值，连同TEM数据，用于所有的分析和现实的噪声水平分配给数据。敏感性分析研究的确定含水量作为一个关键参数估计在反演MRS数据。我们显示的结果为不同的套件（三层）模型，在其中，我们调查的电阻率，含水量，弛豫时间，回路边长，脉冲时刻和测量死时间对含水层中的含水量的测定的影响。对于所有模型套件，比较了顶部导电层和顶部电阻层的效果。此外，我们分析了所有模型的长（40 ms）和短（10 ms）的测量死区时间。分析了噪声水平对参数确定的影响。我们的结论是，一般来说，含水层的电阻率（感兴趣的层，LOI）不影响LOI中的水含量的确定，但是顶层的电阻率增加深度分辨率;在信号在LOI中具有相对长的弛豫时间的情况下，LOI的水含量不显著影响其确定;通过增加LOI中的信号的弛豫时间来改进LOI中的水含量的确定;短的测量死区时间将改进具有相对短的弛豫时间的信号的参数确定;增加环路边长和脉冲时刻的数量不一定改善参数确定。
We present a comprehensive study of the parameter determination of magnetic resonance sounding (MRS) models in a joint MRS and transient electromagnetic (TEM) data analysis scheme. The parameter determination is assessed by calculating the model parameter uncertainties based on an a posteriori model covariance matrix. An entire MRS data set, dependent on pulse moment and time gate values, together with TEM data, is used for all analyses and realistic noise levels are assigned to the data. Sensitivity analyses are studied for the determination of water content as a key parameter estimated during inversion of MRS data. We show the results for different suites of (three-layer) models, in which we investigate the effect of resistivity, water content, relaxation time, loop side length, number of pulse moments and measurement dead time on the determination of water content in a water-bearing layer. For all suites of models the effect of a top conductive and a top resistive layer are compared. Moreover, we analyse all models for a long (40 ms) and short (10 ms) measurement dead time. The effect of noise level on the parameter determination is also analysed. We conclude that, in general, the resistivity of the water-bearing layer (layer of interest, LOI) does not affect the determination of water content in the LOI but the resistivity of the top layer increases depth resolution; the water content of the LOI does not influence its determination considerably in cases where the signal has a relatively long relaxation time in the LOI; determination of the water content in the LOI is improved by increasing the relaxation time of the signal in the LOI; short measurement dead time will improve the parameter determination for signals with a relatively short relaxation time; increasing loop side length and the number of pulse moments do not necessarily improve the parameter determination.