Improvements in pulsed neutron capture logging

Conference · Wed Apr 01 04:00:00 EST 1981 · IEEE Trans. Nucl. Sci.; (United States)

OSTI ID:5648732

Hall, J E; Jacobson, L A; Johnstone, C W

Pulsed neutron capture logs use miniature, sealed tube D,T neutron sources and provide measurement of the thermal-neutron decay time-constant or its inverse, the macroscopic capture cross section. These parameters prove useful in differentiating between oil- or gas-bearing formations and water bearing formations. Such logs are especially useful in detecting hydrocarbons in cased wells where traditional electrical measurements techniques are not applicable. Neutron capture logs are typically made by irradiating a formation with bursts of fast (i.e., 14 MeV) neutrons and measuring the decay of the thermal neutron density in the formation. This is accomplished by counting the gamma rays emitted by formation nuclei during discrete time intervals, or gates, following each neutron burst. Today, the most widely used pulsed-neutron logging system consists of a sliding-gate system in which three measurement gates are utilized. The first two gates are timed to detect the formation capture gamma rays. Such a system and the physics behind it was described four years ago at this conference.

• Research Organization: Schlumberger Well Service, Houston, Texas 77001
• OSTI ID: 5648732
• Report Number(s): CONF-801111-
• Conference Information: Journal Name: IEEE Trans. Nucl. Sci.; (United States) Journal Volume: NS-28:2
• 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
440105 -- Radiation Instrumentation-- Radiometric Instruments-- (-1987)
440400 -- Well Logging Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
47 OTHER INSTRUMENTATION
ACCELERATORS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CAPTURE
DECAY
ELECTRONIC EQUIPMENT
ELEMENTARY PARTICLES
ENERGY RANGE
EQUIPMENT
FAST NEUTRONS
FERMIONS
GEOLOGIC DEPOSITS
HADRONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MEV RANGE
MEV RANGE 10-100
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NEUTRON LOGGING
NEUTRON-GAMMA LOGGING
NEUTRONS
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
PETROLEUM DEPOSITS
PULSED NEUTRON TECHNIQUES
RADIOACTIVITY LOGGING
RADIOISOTOPES
RESOURCES
TRITIUM
TUBES
WELL LOGGING
YEARS LIVING RADIOISOTOPES