Electronics for a Thin Bed Array Induction Logging System

摘要

A logging tool electronics system is disclosed with noise minimization features and pulse compression signal processing techniques to improve the signal-to-noise ratio of array induction logging tools. The borehole is radiated with a magnetic field produced by a configurable multi-frequency and/or multi-amplitude sine wave signal stimulus section driving a fully differential single transmitter coil. Received signals from multiple mutually balanced fully differential receiver arrays are processed by receiver signal chains using adaptive algorithms under firmware control. The received signals are used to determine the conductivity and resistivity of the formation surrounding the borehole.

主权项

1. Apparatus for measuring electrical conductivity of a rock formation surrounding a wellbore, comprising:
a housing adapted for operation of electronic apparatus in a wellbore; means for generating a linear amplitude modulated multi-amplitude sine wave at variable amplitudes enveloped within pulse compressed time intervals and pulse widths; a differentially driven transmitter coil disposed at a selected location on the housing connected for receiving and transmitting the signals from the first electronic circuits; a plurality of mutually balanced fully differential receiver coils disposed at selected locations on the housing, each coil connected to second digitally-controlled electronic circuits for amplifying and filtering signals from the receiver coils; a phase-sensitive detector and low pass filter for receiving signals from the second electronic circuits and the first electronic circuits and producing in-phase and quadrature out-of-phase signals as an analog signal; an analog-to-digital converter to process the analog signal and produce a digital signal for transmission; and a programmable controller having a computer-readable medium programmed for controlling electronic apparatus in the housing.