Real-time casing detection using tilted and crossed antenna measurement
US9115569B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 16, 2012 |
| Grant date | Aug 25, 2015 |
| Priority date | — |
| Expiry date | Oct 23, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/26
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Methods and apparatus for detecting nearby conductors such as pipes, well casing, etc., from within a borehole. A nearby casing string can be detected by transmitting an electromagnetic signal from a transmit antenna on a downhole logging tool and measuring a parallel response signal with a first receive antenna parallel to the transmit antenna and a perpendicular response signal with a second receive antenna perpendicular to the transmit antenna, both receive antennas on the downhole logging tool. As the tool rotates, the transmitting and measuring are repeated to determine the azimuthal dependence of the parallel and perpendicular response signals. The azimuthal dependence is analyzed to determine a diagonal component of said azimuthal dependence for each response signal. Distance to a casing string can be estimated using the diagonal component of each response signal. At least one of the antennas is preferably tilted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.