Formation evaluation combination system for petrophysical well log analysis
US6376838B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 20, 1999 |
| Grant date | Apr 23, 2002 |
| Priority date | — |
| Expiry date | Sep 20, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V11/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of measuring characteristics of a geologic formation, using the time, energy and spatial spectra of gamma rays induced by an accelerator, which allows (i) the measurement of the photoelectric absorption (Pe) factor of the formation using a gamma-ray spectrum detected from gamma rays induced in the formation, (ii) the calculation of a neutron porosity of the formation using the gamma-ray spectrum, and (iii) the determination of a bulk density of the formation using the spectroscopic measurements. The Pe factor may be inferred by directly mapping the spectroscopic measurements. The porosity may be calculated by relating the gamma-ray spectrum to a hydrogen content of the formation. The density may be determined by computing a gamma diffusion length of the formation based on the gamma-ray spectrum. In addition to these measurements, the resistivity of the formation and its spontaneous potential may also be measured using an electromagnetic induction system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.