Method and apparatus measuring electrical anisotropy in formations surrounding a wellbore
US6958610B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 17, 2002 |
| Grant date | Oct 25, 2005 |
| Priority date | — |
| Expiry date | Jul 27, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/28
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A logging tool is disclosed having transmitting and receiving antennas to measure formation anisotropy. The antennas may preferably be combinations of toroidal, horizontal electric dipole, and horizontal magnetic dipole antennas. In one embodiment, the tool: (a) induces a current flow in the tubing or drill string traversing the formation in a borehole; (b) measures a signal difference between two receiver antennas on the drill string; (c) determines an apparent conductivity of the formation from the resistive component of the signal difference; and (d) uses the apparent conductivity to calculate an anisotropy coefficient with a knowledge of the horizontal conductivity. The tool may further determine a second apparent conductivity of the formation from the reactive component of the signal difference, and use both apparent conductivities to calculate the anisotropy coefficient and the horizontal conductivity. The vertical conductivity can also be determined from these two calculated values in the usual manner.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.