Carbon/oxygen well logging method and apparatus
US4937446A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 24, 1989 |
| Grant date | Jun 26, 1990 |
| Priority date | — |
| Expiry date | Aug 24, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/104
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A nuclear spectroscopic method and apparatus for determining hydrocarbon saturation or water saturation of a formation adjacent a well bore is disclosed. Near and far inelastic gamma ray spectra are detected in response to pulses of fast neutrons irradiating the formation and materials in the borehole. Near and far carbon/oxygen (C/O) ratios are extracted from each spectra using predetermined spectra of postulated elements. The near and far C/O ratios are combined to determine a representation of formation hydrocarbon saturation substantially corrected for borehole gamma rays produced by inelastic reaction of fast neutrons and hydrocarbons in the well bore. Shielding of near and far detectors is provided to make the near detector more sensitive to gamma rays emanating from borehole gamma rays and to make the far detector less sensitive to borehole gamma rays and more sensitive to formation gamma rays.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.