Method and apparatus for dual-spaced fast/epithermal neutron porosity measurements

Patent · Tue Dec 23 04:00:00 EST 1986

OSTI ID:6887791

Smith, Jr, H D

A method is described for determining the porosity of earth formations in the vicinity of a well borehole, comprising: (a) irradiating the earth formations in the vicinity of the well borehole with a continuous chemical type source of fast neutrons, (b) detecting the fast neutron population at a first shorter spaced distance from the neutron source in the borehole and generating signals representative thereof, (c) detecting the epithermal neutron population at a second space distance from the neutron source in the borehole and generating signals representative thereof, the second spaced distance being greater than the first spaced distance from the neutron source, (d) forming a ratio of the signals representing the fast and epithermal neutron populations to derive a measurement signal functionally related to the porosity of the earth formations in the vicinity of the borehole, and (e) calibrating the measurement signal according to a predetermined functional relationship to derive a porosity signal quantitatively representative of the porosity of the earth formations in the vicinity of the borehole.

• Assignee: Halliburton Co., Duncan, OK
• Patent Number(s): US 4631405
• OSTI ID: 6887791
• 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
BARYONS
BOREHOLES
CAVITIES
DETECTION
DISTANCE
ELEMENTARY PARTICLES
EPITHERMAL NEUTRONS
EQUIPMENT
FAST NEUTRONS
FERMIONS
GEOLOGIC DEPOSITS
HADRONS
IRRADIATION
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NEUTRON DETECTION
NEUTRON LOGGING
NEUTRON SOURCES
NEUTRONS
NUCLEONS
PARTICLE SOURCES
PETROLEUM DEPOSITS
POROSITY
RADIATION DETECTION
RADIATION SOURCES
RADIOACTIVITY LOGGING
RESOURCES
SIGNALS
SPACE DEPENDENCE
WELL LOGGING
WELL LOGGING EQUIPMENT