Inferential measurement of photoelectric absorption cross-section of geologic formations from neutron-induced, gamma-ray spectroscopy
US6150655A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 1998 |
| Grant date | Nov 21, 2000 |
| Priority date | — |
| Expiry date | Mar 6, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/101
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for inferring the photoelectric absorption of a formation by directly mapping spectroscopic measurements of gamma rays induced in the formation using a fast neutron source. The mapping is accomplished by creating a polynomial function based on counts of gamma-ray events in the gamma-ray energy spectrum; the coefficients of the polynomial function are determined in known calibration environments, and the value of the polynomial is the inferred photoelectric absorption parameter. The spectroscopic measurements are preferably generated by sorting gamma-ray counts of the gamma-ray spectrum into a plurality of energy-dependent channels, and measuring these gamma-ray energy distributions during different portions of the firing cycle where different types of dominant gamma-ray production reactions occur.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.