Directional resistivity measurements for azimuthal proximity detection of bed boundaries
US6181138A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 22, 1999 |
| Grant date | Jan 30, 2001 |
| Priority date | — |
| Expiry date | Feb 22, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An azimuthally tunable resistivity measurement tool is provided. In one embodiment, the tool comprises a set of three skewed receiver antennas and a transmitter antenna. The three skewed receiver antennas are oriented in equally-spaced azimuthal directions to give them preferential sensitivity in those directions. The transmitter antenna transmits a radio-frequency signal that propagates through the formation surrounding a borehole. The signals from the three receiver antennas can be measured and combined to synthesize the signal that would be received by a virtual antenna oriented in any desired direction. Accordingly, virtual receivers oriented perpendicular to the tool axis and with variable azimuthal orientations can be synthesized. The orientation of such a virtual receiver that has a maximized receive signal amplitude can be used to identify the direction of a nearby bed boundary, and the maximized amplitude can be used to estimate the distance to the boundary. In another embodiment, the tool comprises a set of three skewed transmitter antennas and a receiver antenna. The signal responses of the receiver antenna to each of the transmitter antennas can be measured and combined…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.