Formation density logging MWD apparatus
US5134285A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 1991 |
| Grant date | Jul 28, 1992 |
| Priority date | — |
| Expiry date | Jan 15, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A measurement-while-drilling (MWD) density tool is provided which incorporates a single gamma ray source and a pair of longitudinally displaced and mutually aligned detector assemblies (i.e., dual scintillation counters). A nuclear source is mounted in a pocket in the sub wall and partially surrounded by gamma ray shielding. The subwall section adjacent the source is expanded radially so as to define a lobe which displaces mud thus reducing borehole and mudcake effects. The two detector assemblies are mounted within a cavity or hatch formed in the subwall and enclosed by a detector hatch cover under ambient pressure. The detector assemblies are fixedly spaced from the source and are also partially surrounded by gamma ray shielding to provide good formation response. The hatch cover is secured to the sub by bolts and contains radiation transparent windows therethrough in alignment with the detector assemblies. A threaded-on fluid displacement sleeve is positioned on the sub and over the detector hatch cover. This sleeve has several important functions including the displacement of borehole fluids, reducing mudcaking which might have an adverse effect on the measurement and maintaini…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.