An in-situ check of the epithermal neutron log calibration

Conference · Wed Sep 01 04:00:00 EDT 1993

OSTI ID:10192082

Burkhard, N R

The epithermal neutron log is used to measure the water content of the formation. The large hole epithermal neutron sonde (ENS) that we utilize at the Nevada Test Site (NTS) has been calibrated in the Hydrogen Content Test Facility (HCTF). These calibrations are used to correct the measured neutron count rate for the effects of tool stand-off and density. For sometime, the suspicion has existed that the water contents that are calculated from the ENS data are too large. Hole U2gj represented a unique opportunity to check the validity of the ENS calibration under realistic logging conditions; a portion of the hole had been cemented and re drilled and then logged. The cements have a known water content and can be used as an in situ calibration check. I found that the water contents from the log data after processing with the existing calibrations are consistent with these known cement water contents. In addition, the study indicates that the raw neutron data might be more appropriately smoothed by using a median smoother rather than the currently utilized mean smoother.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 10192082
• Report Number(s): UCRL-JC--113340; CONF-9309103--3; ON: DE94002007
• Country of Publication: United States
• Language: English

Related Subjects

440400
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
450201
47 OTHER INSTRUMENTATION
58 GEOSCIENCES
580000
CALIBRATION
CEMENTS
CONTAINMENT
EPITHERMAL NEUTRONS
GEOSCIENCES
MOISTURE GAGES
NEUTRON LOGGING
NEUTRON PROBES
NEVADA TEST SITE
WATER
WELL LOGGING INSTRUMENTATION