Logging while drilling apparatus with multiple depth of resistivity investigation
US5428293A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 8, 1993 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | Nov 8, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In an MWD system, a mandrel for connection to the drill bit is set forth which supports shallow, intermediate and deep measuring resistivity systems. By transmitting upwardly and downwardly in alternate fashion, and receiving the transmitted signal at pairs of receiver coils, transmitted signal phase shift and attenuation are measured. A method of measuring is set forth which includes making resistivity measurements close to the drill bit at increasing ranges from the borehole so that formation resistivity prior to fluid invasion is obtained. Measurements are thus provided of formation resistivity before, during and after fluid invasion. The method also accommodates formations which have a relative dip angle with respect to the well borehole.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.