大地电流勘探用的調制式直流放大器

一、引言大地电流法和由它发展起来的大地电磁測探法是利用天然的大地电流和大地电磁場来勘探石油构造和研究大地构造的方法。近年来,由于石油勘探事业发展的需要,很多国家,特別是苏联在发展此方法方面取得了很多新的进展,例如研究高电阻屏蔽层下的結晶基岩面、利用大地电磁場各种頻率的电磁分量的比值进行地层区分等,这就更引起了大家的重視。

A DIRECT CURRENT AMPLIFIER OF THE MODULATION TYPE FOR THE TELLURIC CURRENT METHOD OF GEOPHYSICAL PROSPECTING

In this article, the construction of a two-channel direct current amplifier of the modulation type, with the results of laboratory and field tests are described. It gives briefly the principle of the amplifier and also an account of. the experiences accumulated in the process of construction and testing, especially relating to the effect of noise level and the way of its preventing. As the results of laboratory and field tests indicate, this amplifier has relatively low amplitude and phase distortion to wave signals below 1 Hertz, noise level less than 0.5 microvolt, drift of the zero point, say within 1 hour, less than 5 microvolt. Hence this amplifier is considered suitable for the measurement of very weak and low frequency signals and can be. recommended for general field use.