Methods and apparatuses for measuring the resistivity of drilling mud in a borehole
US6369575B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 18, 1999 |
| Grant date | Apr 9, 2002 |
| Priority date | — |
| Expiry date | Nov 18, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/20
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of measuring the resistivity of drilling mud in a borehole passing through a terrestrial formation includes the steps of a) inserting a sonde into the borehole, the sonde having an elongate body provided with at least one annular current electrode (A0, A′0) and at least two annular guard electrodes (A, A′, A1, A′1, A2, A′2) situated on either side of the annular current electrode; b) performing computed focusing to simulate an operating mode in which at least one current I0 is emitted into the surrounding formation from the annular current electrode, the current I0 being focused in the formation by emitting two currents I1 and I′1 from the two annular guard electrodes situated on either side of the annular current electrode; and c) producing a signal representative of the resistivity Rm of the drilling mud from the simulated operating mode. Apparatus for measuring the resistivity of drilling mud in a borehole includes the sonde, and electronic circuitry for performing computed focusing and computing a signal representative of the resistivity Rm of the drilling mud on the basis of the computed focusing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.