Calibration of a neutron log in partially saturated media. Part II. Error analysis

Conference · Fri Mar 20 04:00:00 EST 1981

OSTI ID:6795576

Hearst, J R; Kasameyer, P W; Dreiling, L A

Four sources or error (uncertainty) are studied in water content obtained from neutron logs calibrated in partially saturated media for holes up to 3 m. For this calibration a special facility was built and an algorithm for a commercial epithermal neutron log was developed that obtains water content from count rate, bulk density, and gap between the neutron sonde and the borehole wall. The algorithm contained errors due to the calibration and lack of fit, while the field measurements included uncertainties in the count rate (caused by statistics and a short time constant), gap, and density. There can be inhomogeneity in the material surrounding the borehole. Under normal field conditions the hole-size-corrected water content obtained from such neutron logs can have an uncertainty as large as 15% of its value.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6795576
• Report Number(s): UCRL-85102; CONF-810616-2
• Country of Publication: United States
• Language: English

Related Subjects

440400* -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
CALIBRATION
EQUIPMENT
ERRORS
TEST FACILITIES
WELL LOGGING EQUIPMENT