Title: Pulsed neutron well logging apparatus having means for determining background radiation

Abstract: A neutron generator in a well logging instrument is periodically pulsed and has an off period between pulses of 1000 microseconds. A neutron detector is gated on at intervals of 400-500, 550-650, and 700-800 microseconds, respectively, following the termination of each burst of fast neutrons. Circuitry is provided for determining the background radiation by the equation: ##EQU1## where B is the background, and N.sub.1, N.sub.2 and N.sub.3 are the counts observed during the three gates, respectively. Circuitry is also provided for determining the macroscopic absorption (.SIGMA.) from the equation: ##EQU2## where V is the velocity of thermal neutrons, being a constant and .DELTA.t represents an increment of time.

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Other info:

Inventors: Randall, Russel R. (Houston, TX, US)

Application Number: 847986
Filing Date: 1977-11-02
Publication_date: 1979-06-05
Assignee: Dresser Industries, Inc. (Dallas, TX)
Primary Class(es): 250/262 250/269.5, 702/8
Other Classes:
US Patent Ref:

3706884

Dec, 1972

Youmans

250/269.

Other Refs:
Primary Examiner: Willis, Davis L.
Assistant Examiner:
Attorney: Van Winkle; Roy L.