Real time determination of casing location and distance with tilted antenna measurement
US8749243B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 2011 |
| Grant date | Jun 10, 2014 |
| Priority date | — |
| Expiry date | Jun 1, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
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 first antenna on a downhole logging tool and measuring a response signal with a second antenna. As the tool rotates, the transmitting and measuring are repeated to determine the azimuthal dependence of the response signal. The azimuthal dependence is analyzed to determine an diagonal component and a cross component. The amplitude of the diagonal component is indicative of distance to the conductive feature. Direction can be determined based on the diagonal component alone or in combination with the cross component. Sinusoidal curve fitting can be employed to improve accuracy of the distance and direction estimates. At least one of the antennas is preferably tilted. Measurement results are presented for parallel tilted and perpendicular tilted antennas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.