Pulsed neutron well logging apparatus having means for determining background radiation

Patent · Tue Jun 05 04:00:00 EDT 1979

OSTI ID:5546930

Randall, R R

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 to 500, 550 to 650, and 700 to 800 microseconds, respectively, following the termination of each burst of fast neutrons. Circuitry is provided for determining the background radiation by the equation: B = N/sub 1/ X N/sub 3/ - N/sub 2//sup 2//N/sub 1/ + N/sub 3/ - 2N/sub 2/ 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: ..sigma.. = 1/V..delta..t Log (N/sub 1/ - B/N/sub 2/ - B) where V is the velocity of thermal neutrons, being a constant and ..delta..t represents an increment of time.

• Assignee: Dresser Industries, Inc.
• Patent Number(s): US 4157469
• OSTI ID: 5546930
• Country of Publication: United States
• Language: English

Related Subjects

440400* -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
DESIGN
DETECTION
GAMMA DETECTION
MEASURING INSTRUMENTS
NEUTRON DETECTION
NEUTRON DETECTORS
NEUTRON LOGGING
NEUTRON SOURCES
PARTICLE SOURCES
PULSED NEUTRON TECHNIQUES
RADIATION DETECTION
RADIATION DETECTORS
RADIATION SOURCES
RADIOACTIVITY LOGGING
WELL LOGGING