Formation density measurement utilizing pulse neutrons
US5900627A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1997 |
| Grant date | May 4, 1999 |
| Priority date | — |
| Expiry date | Jun 19, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/104
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A device for measuring the density of a formation uses a high-energy pulsed neutron source which induces gamma rays in the formation, and determines a gamma diffusion length of the formation based on the attenuation of gamma rays produced by inelastic scattering of fast neutrons. The borehole tool houses the neutron source along with a near gamma ray detector and a far gamma ray detector. The gamma ray detectors are located at different distances from the fast neutron source and spaced sufficiently from the fast neutron source such that dependence of inelastic gamma counts on fast neutron transport and gamma production of the formation is substantially reduced. Gamma ray events can be sorted and counted in time- and energy-dependent bins. The present invention has several advantages over gamma-gamma logging, including deeper penetration of gamma, and is also superior over systems which measure, e.g., hydrogen-based porosity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.