Coil array for a high resolution induction logging tool and method of logging an earth formation
US5065099A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1990 |
| Grant date | Nov 12, 1991 |
| Priority date | — |
| Expiry date | Oct 29, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An induction tool including a coil array having a plurality of transmitter coils and a plurality of receiver coils. Each plurality of coils is symmetrically arranged on an insulated mandrel about a selected point. The induction tool also includes an oscillator circuit that provides an alternating frequency signal to the transmitter coils. A receiver circuit is connected to the receiver coils to measure signals indicative of the voltages induced on these receiver coils to the surface. By varying the spacing between the receiver coils and transmitter coils it is possible to independently vary the vertical and radial measurement capabilities of the tool of the present invention. A dual induction tool having high vertical resolution is also disclosed. The dual induction tool includes a pair of transmitter/receiver coil arrays, each transmitter/receiver coil array having a different transmitter-to-receiver coil spacing and substantially indentical vertical resolution. A single receiver coil is located at a selected point on an insulated sonde and a pair of variable symmetrically disposed bucking coils are located on either side of the receiver coil. Two pairs of identical transmitter co…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.