Accelerator-based methods and apparatus for measurement-while-drilling
US5539225A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1994 |
| Grant date | Jul 23, 1996 |
| Priority date | — |
| Expiry date | Sep 16, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/107
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Measurement-while-drilling apparatus includes a 14 MeV neutron accelerator, a near-spaced neutron detector which primarily senses source neutrons and whose output is proportional to source strength, one or more intermediately-spaced epithermal neutron detectors eccentered against the drill collar wall and primarily responsive to formation hydrogen concentration, and a third far-spaced radiation detector, either gamma ray or neutron, primarily responsive to formation density. The intermediately-spaced and far-spaced detector outputs, normalized by the near-spaced detector output, are combined to provide measurements of porosity, density and lithology and to detect gas. A thermal neutron detector and/or a gamma ray detector may also be provided at intermediate spacings to provide additional information of interest, such as standoff measurements and spectral analysis of formation composition. Tool outputs are related to the angular or azimuthal orientation of the measurement apparatus in the borehole.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.