Method and apparatus for detecting deep conductive pipe
US8917094B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 12, 2011 |
| Grant date | Dec 23, 2014 |
| Priority date | — |
| Expiry date | Sep 10, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/18
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Downhole tools and techniques acquire information regarding nearby conductors such as pipes, well casing, and conductive formations. At least some method embodiments provide a current flow along a drill string in a borehole. The current flow disperses into the surrounding formation and causes a secondary current flow in the nearby conductor. The magnetic field from the secondary current flow can be detected using one or more azimuthally-sensitive antennas. Direction and distance estimates may be obtainable from the azimuthally-sensitive measurements, and can be used as the basis for steering the drillstring relative to the distant conductor. Possible techniques for providing current flow in the drillstring include imposing a voltage across an insulated gap or using a toroid around the drillstring to induce the current flow.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.