Method and system for determining thermal neutron lifetime of earth formations
US4350888A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 2, 1980 |
| Grant date | Sep 21, 1982 |
| Priority date | — |
| Expiry date | Sep 2, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Methods and apparatus are provided for determining the thermal neutron lifetime of earth formations in the vicinity of a well borehole. The borehole environs are irradiated with pulses of fast neutrons. Between neutron pulses capture gamma rays are detected in at least six, non-overlapping, sequential time intervals and count rate signals representative thereof are generated. Comparisons of the six count rate signals are made to determine which ones have been affected by a borehole component. Only those count rate signals not affected by the borehole component are used to determine the thermal neutron lifetime by a least-squares fitting technique.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.