DEVICE FOR MEASUREMENT OF NATURAL ELECTROMAGNETIC SIGNALS IN WELL Russian patent published in 2020 - IPC G01V3/18 G01R29/08 

FIELD: geophysics.

SUBSTANCE: invention relates to geophysics and is used in investigation of wells in order to determine disturbed and fractured zones. Summary: device is a receiver of electromagnetic signals operating on the principle of direct amplification, and comprises ferritic antenna 1, eight capacitors (10–17) and eight resistors (2–9) of different values, a first capacitor switch 18, amplifier 20, band-pass filter 21, rectifier 22, analogue-to-digital converter 23, output unit 25, unit control 26 and second analogue switch 19. Resistors are connected by their one end together and connected to ferrite antenna. Second ends of the resistors are connected to the inputs of the first switch, the outputs of which are connected through the second switch to the input of the amplifier. Output of the amplifier is connected to the input of the band-pass filter. Capacitors together with ferrite antenna in each cycle of device operation determine frequency of received signals, which corresponds to degree of disturbance or fracturing of rocks at depth of device installation in well. Installation of resistors of definite resistance in the input circuit makes it possible to ensure constant Q-factor regardless of the tuning frequency.

EFFECT: possibility of receiving electromagnetic signals in the entire operating frequency range enables to follow dynamics of nucleation and development of structural destruction of rocks.

1 cl, 2 dwg