Well logging method and apparatus providing multiple depth of investigation using multiple transmitters and single receiver pair having depth of investigation independent of formation resistivity
US5278507A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 14, 1991 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Jun 14, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/30
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus and method for determining formation resistivity at a plurality of radial distances from an earth borehole uses a single receiver pair and a plurality of electromagnetic energy transmitters sequentially spaced along the apparatus from the receiver pair, such transmitters being sequentially pulsed at approximately 1-2 MHz each to provide time separation between the pulsing of the plurality of transmitters. The closest spaced transmitter is spaced a predetermined distance from the closer receiver to make the depth of investigation of the closest transmitter essentially independent of formation resistivity. Alternatively, a single transmitter is spaced a predetermined distance from the closer receiver to make the depth of investigation of such transmitter essentially independent of formation resistivity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.