Neutron logging in partially saturated media

Conference · Wed Jan 01 04:00:00 EST 1975

OSTI ID:4044774

Hearst, J R

At the Lawrence Livermore Laboratory the behavior of epithermal neutron logging equipment in large holes in partially saturated alluvium and in ashfall and ashflow tuff is being studied. Monte Carlo neutron transport calculations indicate that the number of epithermal neutrons from either a fission or 14-MeV source depends not only on the water content of the medium, but also on its bulk density. Curves as functions of both parameters have been developed and an interpolation method devised. Attempts to calibrate neutron logs by comparing log-measured water content with water content from cores result in unacceptably large errors. Part of the error is due to the fact that commercial neutron logs are quite sensitive to hold size variations. It is shown that with proper shielding the hole size effect can be eliminated. An effort is in progress to study the two water contents, bulk density, and material type in a number of holes to determine whether core data calibration would be satisfactory with proper corrections. (auth)

• Research Organization: Univ. of California, Livermore
• NSA Number: NSA-33-029407
• OSTI ID: 4044774
• Country of Publication: United States
• Language: English

Related Subjects

*MOISTURE GAGES-- CALIBRATION
*WELL LOGGING-- MOISTURE GAGES
440400* --Instrumentation--Well Logging Instrumentation
BOREHOLES
COUNTING RATES
DENSITY
EPITHERMAL NEUTRONS
EQUIPMENT
HYDROGEN
MONTE CARLO METHOD
N46200* --Instrumentation--Radiometric Instruments
NEUTRON SOURCES
RADIOMETRIC GAGES
SIZE
TEST FACILITIES
WATER