Geochemical logging apparatus and method for determining concentrations of formation elements next to a borehole
US5021653A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 7, 1990 |
| Grant date | Jun 4, 1991 |
| Priority date | — |
| Expiry date | Feb 7, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/101
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Logging method and tool string for identifying and determining the concentrations of subsurface formation elements next to a borehole, by (i) using a low energy neutron source (either a chemical source, e.g. a .sup.252 Cf, or a deuterium-deuterium electronic source), and (ii) detecting and counting the delayed gamma rays resulting from the activation by the neutrons of atoms of at least one element of interest (e.g. aluminum). Two gamma ray detectors may also be disposed on either side of the low energy neutron source, for detecting and counting the prompt gamma rays resulting from the capture of neutrons by atoms of elements, such as Si, Ca, Fe, S, H, or Cl, Gd, Ti, or K. The low energy neutron source is used for both the "activation" and the "capture" measurements. The tool string may also include a natural gamma ray tool for the determination of uranium, thorium and potassium, and for measuring the background to be subtracted from the gross Al activation measurement.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.