Monte Carlo simulation of the temporal and spectral responses of the pulsed-neutron logging principle
Thesis/Dissertation
·
OSTI ID:5352104
A Monte Carlo model which simulates the response of a pulsed-neutron logging tool for either open or cased borehole is developed. The model simulates the transport of neutrons originating from a (D,T) source within the tool through the borehole, the casing, and the formation. Gamma rays generated from (n,..gamma..) and (n,n',..gamma..) reactions are tracked and detected by NaI(TI) detectors that are located within the tool. The gamma-ray counting rate can be computed as a function of time to get the temporal response of the tool. Also, the code is capable of computing the gamma-ray energy spectrum within user-specified time gates. The simulation is done in three-dimensional geometry because of the eccentric placement of the tool. An option is provided to simulate the effects of a high absorption layer such as shale in the formation. Computer storage and run time are minimized through the use of a variety of efficient data storage and variance reduction methods specifically suited for the particular problem. The temporal response calculated by the code is benchmarked against experimental data on laboratory-test pits supplied by one of the petroleum service companies. The agreement appeared very good in twelve out of the fourteen cases. Experimental data on spectral tools are unavailable at the present time. The Monte Carlo code is expected to be used in pulsed-neutron logging-tool design and in well-log interpretation.
- Research Organization:
- North Carolina State Univ., Raleigh (USA)
- OSTI ID:
- 5352104
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
440400* -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
BOREHOLES
CAVITIES
COMPUTERIZED SIMULATION
EQUIPMENT
MONTE CARLO METHOD
NEUTRON LOGGING
NEUTRON-GAMMA LOGGING
PULSED NEUTRON TECHNIQUES
RADIOACTIVITY LOGGING
RESOLUTION
SIMULATION
SPECTRAL RESPONSE
TIME RESOLUTION
TIMING PROPERTIES
WELL LOGGING
WELL LOGGING EQUIPMENT
47 OTHER INSTRUMENTATION
BOREHOLES
CAVITIES
COMPUTERIZED SIMULATION
EQUIPMENT
MONTE CARLO METHOD
NEUTRON LOGGING
NEUTRON-GAMMA LOGGING
PULSED NEUTRON TECHNIQUES
RADIOACTIVITY LOGGING
RESOLUTION
SIMULATION
SPECTRAL RESPONSE
TIME RESOLUTION
TIMING PROPERTIES
WELL LOGGING
WELL LOGGING EQUIPMENT