Background subtraction system for pulsed neutron logging of earth boreholes
A neutron generator in well logging instrument is pulsed 100 times having a time between pulses of 1400 microseconds. This is followed by an off period of four cycles wherein 2800 microseconds is allowed for capture radiation to decay to an insignificant level and the remaining 2800 microseconds is used to measure background radiation. This results in the neutron source being disabled four pulses after every hundred pulses of operation, or approximately a 4 percent loss of neutron output. A first detector gate is open from 400 to 680 microseconds and a second detector gate is open from 700 to 980 microseconds. During the 100 cycles, each of the gates is thus open for 280 microseconds times 100 for a total of 28,000 microseconds. By scaling the gate count rate by a factor of 10, the background is subtracted directly.
- Assignee:
- Dresser Industries, Inc.
- Patent Number(s):
- US 4041309
- OSTI ID:
- 6801892
- Country of Publication:
- United States
- Language:
- English
Similar Records
Pulsed neutron well logging apparatus having means for determining background radiation
Background subtraction system for pulsed neutron logging of earth boreholes
Related Subjects
440400* -- Well Logging Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
47 OTHER INSTRUMENTATION
BACKGROUND RADIATION
COUNTING RATES
DATA ACQUISITION
EQUIPMENT
NEUTRON LOGGING
NEUTRON-GAMMA LOGGING
NEUTRON-NEUTRON LOGGING
PULSED NEUTRON TECHNIQUES
RADIATIONS
RADIOACTIVITY LOGGING
WELL LOGGING