修正的DOI方法在确定直流电法有效探测深度中的应用

Modified DOI method applied in the determination of the effective depth of investigation with direct current electrical method

直流电法有效探测深度的确定是地球物理电法研究的焦点,其与最终数据解释的可靠程度紧密相连,不准确的探测深度可能会造成漏解释或过度解释.修正的DOI(Depth of Investigation)方法被用于确定直流电法的有效探测深度.该方法是在DOI法的基础上提出,针对原始采集数据的两个不同电阻率参考模型的反演结果,利用统计学方法和无约束非线性优化方法处理数据,最终得到透明索引指标,从而获得有效探测深度边界.该方法有效规避了人为选用截断阈值来确定有效探测深度的缺点.在工程实例应用上也取得了较好的效果,这对未来直流电法有效探测深度的确定具有重要应用价值.

The determination of the effective depth of investigation with direct current electrical method is a focus point for geophysical electrical method, which is closely related with the accuracy of the final data interpretations. Inaccurate depths of investigation may cause misinterpretations or over-interpretations of results. A new method for determining the effective depth of investigation is introduced well in this paper that is called scaled DOI （depth of investigation） method. This method was proposed based on the DOI method. The inversions of two reference models with different resistivities of original data were carried out. Then, the inversion data were processed by the statistical methods and unconstrained nonlinear optimization method. Finally, a transparent index was obtained to determine the border of the effective depth of investigation. The shortcoming of artificial selection of cut-off threshold values was avoided successfully in the determination of the effective depth of investigation. It also achieved good results in the engineering application, which has significant application value for the determination of the effective depth of investigation with direct current electrical method.