Borehole compensated density logs corrected for naturally occurring gamma rays
US4529877A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 24, 1982 |
| Grant date | Jul 16, 1985 |
| Priority date | — |
| Expiry date | Nov 24, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for measuring formation density is disclosed. It provides a corrected gamma gamma-type density log having a correction for the adverse effects of gamma radiation from thorium, uranium and potassium ore bodies. The adjacent formation is irradiated with gamma radiation preferably from a cesium (Cs.sup.137) source which emits gamma radiation at 0.663 Mev. Two differently longitudinally spaced detectors are used, a short spaced detector and a long spaced detector. A gamma ray spectrum observed at one of the detectors is broken down into four energy windows across the spectrum and count rate signals are determined and corrected to separate the naturally occurring gamma radiation from the scattered gamma radiation. This information may then be combined with count rate information from the other detector, thereby yielding a compensated density log corrected from naturally occurring gamma rays.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.