Earth formation pulsed neutron porosity logging system utilizing epithermal neutron and inelastic scattering gamma ray detectors
US4122339A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 20, 1977 |
| Grant date | Oct 24, 1978 |
| Priority date | — |
| Expiry date | Apr 20, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/105
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MEV pulsed neutron source, an epithermal neutron detector and an inelastic scattering gamma ray detector is moved through a borehole. The detection of inelastic gamma rays provides a measure of the fast neutron population in the vicinity of the detector. Repetitive bursts of neutrons irradiate the earth formation and, during the bursts, inelastic gamma rays representative of the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.