Doubly-compensated dual-detector density logging apparatus

Patent · Tue Sep 13 04:00:00 EDT 1977

OSTI ID:6440500

Ellis, D V

A technique is described for dtermining the density of an earth formation with a logging sonde including a gamma ray source and two gamma ray detectors spaced at different distances from the source. The count rate of the sort-spaced detector is measured in two energy ranges covering back-scattered gamma rays which have undergone relatively low and high attenuations. A first density correction is determined from the difference between the apparent density derived from the count rate of the long-spaced detector and the density derived from the count rate of the short-spaced detector in the energy range covering gamma rays with relatively low attenuation. A second density correction is determined from the difference between the densities derived from the two short-spaced detectors' count rates. These two density corrections are added to the apparent density to give the true formation density.

• Assignee: Schlumberger Technology Corp.
• Patent Number(s): US 4048495
• OSTI ID: 6440500
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200 -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
440400* -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
BACKSCATTERING
BOREHOLES
CAVITIES
COLLIMATORS
CONTROL
COUNTING RATES
DENSITY
DESIGN
DETECTION
GAMMA DETECTION
GAMMA SOURCES
GAMMA-GAMMA LOGGING
GEOLOGIC FORMATIONS
MEASURING INSTRUMENTS
PHYSICAL PROPERTIES
PROBES
RADIATION DETECTION
RADIATION DETECTORS
RADIATION SOURCES
RADIOACTIVITY LOGGING
ROCKS
SCATTERING
SCINTILLATION COUNTERS
SOILS
WELL LOGGING