三层倾斜层的电测深曲线正演计算与解析

本文是探讨三层倾斜层的直流电测深问题。文中通过三层倾斜层的数学模型,就各种参数(第一、二倾斜层的倾角及各倾斜层的电阻率值变化,测线平行、正交、斜交于倾斜层走向)进行了大量的电测深正演计算,并对正演计算结果加以探讨。计算结果表明,其值与三层水平层测深结果有较大的差别,如曲线的尾支渐近值差异,垂直倾斜层走向布极的测深曲线产生畸变,以及在某些地电参数下,测深曲线无法正确地反映地下的地电断面等。因此,在野外实际工作中,对于利用三层水平层的理论计算结果来解释三层倾斜层时,必须注意其解释误差。

FORWARD CALCULATION AND ANALYSIS OFELECTRICAL SOUNDING CURVES OF THREEINCLINED LAYERS

This paper deals preliminarily with the problem of direct-current electrical sounding for three inclined layers. Using the mathematical model for three inclined layers, the author conducted lots of forward calculations of electrical sounding with reference to various parameters such as dips of the first and thesecond inclined layer, variation in resistivity for every inclined layer, and the cases when the line parallel, perpendicular and oblique to the strike of the inclined layer respectively. The results of the calculations indicate that the values obtained are quite different from the results of electrical sounding for three horizontal layers, e. g., the difference in asymptotic values of tails of the curves;the distortion of electrical sounding curves when electrodes are arranged perpendicular to the strike of the inclined layer;the impossibility for electrical sounding curves to reflect correctly underground geoelectric cross section with certain geoelectric parameters. Consequently,when theoretical calculations for three horizontal layers are used to interpret three inclined layers, due attention-should be paid to the interpretation errors.