Method and apparatus for determining formation resistivity in a cased well using three electrodes arranged in a wheatstone bridge
US5563514A · kind A · utility
30Cited by
20References
35Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 30, 1994 |
| Grant date | Oct 8, 1996 |
| Priority date | — |
| Expiry date | Mar 30, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/20
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention relates to a method of determining the resistivity of a geological formation through which a metal-cased borehole passes, by means of at least three electrodes in contact with the casing and spaced apart in the longitudinal direction of the borehole. In order to eliminate the effect of any differences between the two sections of casing delimited by the electrodes, a circuit connected to the electrodes and forming a Wheatstone bridge is balanced, with said sections of casing constituting two of the resistances in said Wheatstone bridge circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.