Dynamic range control of electrode pad current in well logging tools
US4514809A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1982 |
| Grant date | Apr 30, 1985 |
| Priority date | — |
| Expiry date | Apr 30, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/24
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In apparatus for investigating earth formations traversed by a borehole, improved methods and apparatus are provided for achieving dynamic range control of formation measurements. In one embodiment adapted to formation resistivity measurements, a well logging tool moving through a borehole emits a current into the adjacent earth formation, and a corresponding measurement voltage correlative to the resistivity is sampled at discrete elevations as the tool traverses the borehole. An average of these voltage measurements is formed. When the magnitude of this average exceeds or drops below a predetermined range, the magnitude of the survey voltage is decreased or increased respectively by a discrete amount.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.