Stabilized radioactive logging method and apparatus
US4300043A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 29, 1979 |
| Grant date | Nov 10, 1981 |
| Priority date | — |
| Expiry date | May 29, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An oil well logging apparatus is disclosed for detecting radiation emanating or returning from an oil well formation. The apparatus has a scintillation crystal adjacent a photomultiplier tube for detecting light flashes generated in the crystal by radiation. A low energy gamma source is included in the crystal for generating a known peak of pulse counts in the energy spectrum. A cadmium shield is placed over the crystal to block low energy radiation which would tend to mask the peak of gamma source pulses. This known peak is divided electrically downhole by window discriminators such that the peak is equally divided into two windows at a standard condition. If the frequency of pulses in one window varies from the frequency of pulses in the second window, a correction factor is generated downhole for varying the pulse height of the entire spectrum until the frequency of pulses in each window is again equal. Salinity compensation is also accomplished by samarium sleeves in the logging sonde.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.