Well logging method and apparatus involving electromagnetic wave propagation providing variable depth of investigation by combining phase angle and amplitude attenuation
US5389881A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 22, 1992 |
| Grant date | Feb 14, 1995 |
| Priority date | — |
| Expiry date | Jul 22, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/30
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An electromagnetic wave propagation well logging system for measuring dielectric constant and/or formation resistivity (conductivity) includes three transmitters and a pair of receivers. The receiver pair is connected to circuitry that measures the amplitude ratio between the receivers, as well as the phase angle difference between the receivers. Signals representative of the detected amplitude ratio and of the detected phase angle difference are combined in such a manner as to make the depth of investigation controllable. Methods are also disclosed for maintaining a common depth of investigation as the well logging instrument traverses the earth borehole.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.