Multi-component induction instrument
US6677756B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 3, 2001 |
| Grant date | Jan 13, 2004 |
| Priority date | — |
| Expiry date | Aug 3, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved induction tool for formation resistivity evaluations. The tool provides electromagnetic transmitters and sensors suitable for transmitting and receiving magnetic fields in radial directions that are orthogonal to the tool's longitudinal axis with minimal susceptibility to errors associated with parasitic eddy currents induced in the metal components surrounding the transmitter and receiver coils. The present invention provides increased effective tool surface impedance by increasing self-inductance of the paths in which induced eddy currents flow on the surface of the multi-component induction instruments. The tool enables downhole tool designers to build more effective and better-protected radial induction arrays for existing and future downhole instruments operating in the frequency and/or time domains. In this case the array measurement results contain information primarily about the formation's vertical resistivity. The tool makes it possible to combine radial arrays with coaxial arrays that conventionally measure horizontal formation resistivity. This combination enables obtaining a full resistivity tensor to evaluate formation resistivity anisotropy. The tool prov…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.