Simultaneous thermal neutron lifetime and boron content well log
Patent
·
OSTI ID:7322117
A system for logging earth formations traversed by a borehole is described wherein a high energy pulsed neutron source (14 MeV) repetitively irradiates earth formations. Two time gates operated after each neutron pulse are provided for detecting count rates from which the decay time and the macroscopic capture cross-section ..sigma.. can be determined. Background gate means are also provided to eliminate the effects of background and detector radiation. In the detection system, output pulses whose voltage level is proportional to the energy detected are produced. A cut-off voltage level is set at approximately 0.8 MeV, which is above the energy of gamma rays produced following neutron capture by the element boron and below the energy of most gamma rays produced following capture by all other significant formation elements. By comparison of the count rates (obtained by summing these voltage pulses) in a boron containing formation with macroscopic capture cross-section ..sigma.. to the count rate in an unborated formation having the same ..sigma.. value, the concentration of boron can be determined and plotted as a function of depth. 9 claims, 4 figures.
- Assignee:
- Texaco Inc.
- Patent Number(s):
- US 4002904
- OSTI ID:
- 7322117
- Country of Publication:
- United States
- Language:
- English
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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
BARYON REACTIONS
BARYONS
BORON
CAPTURE
COUNTING RATES
ELECTRONIC CIRCUITS
ELEMENTARY PARTICLES
ELEMENTS
EQUIPMENT
EXPLORATION
FAST NEUTRONS
FERMIONS
GATING CIRCUITS
GEOLOGIC DEPOSITS
HADRON REACTIONS
HADRONS
NATURAL GAS DEPOSITS
NEUTRON LOGGING
NEUTRON REACTIONS
NEUTRON SOURCES
NEUTRON-GAMMA LOGGING
NEUTRONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEONS
PARTICLE SOURCES
PETROLEUM DEPOSITS
PULSED NEUTRON TECHNIQUES
RADIATION SOURCES
RADIOACTIVITY LOGGING
RESOURCES
SEMIMETALS
WELL LOGGING
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
440400 -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
BARYON REACTIONS
BARYONS
BORON
CAPTURE
COUNTING RATES
ELECTRONIC CIRCUITS
ELEMENTARY PARTICLES
ELEMENTS
EQUIPMENT
EXPLORATION
FAST NEUTRONS
FERMIONS
GATING CIRCUITS
GEOLOGIC DEPOSITS
HADRON REACTIONS
HADRONS
NATURAL GAS DEPOSITS
NEUTRON LOGGING
NEUTRON REACTIONS
NEUTRON SOURCES
NEUTRON-GAMMA LOGGING
NEUTRONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEONS
PARTICLE SOURCES
PETROLEUM DEPOSITS
PULSED NEUTRON TECHNIQUES
RADIATION SOURCES
RADIOACTIVITY LOGGING
RESOURCES
SEMIMETALS
WELL LOGGING