Method and apparatus for determining formation resistivity in a cased well
CA 2119395 C · Owner: Schlumberger Canada Limited · Inventors: Moulin, Pierre Alexis
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention relates to a method of determining the resistivity of a geological formation through which a metal-cased borehole passes by means of at least three electrodes in contact with the casing and spaced apart in the longitudinal direction of the borehole. In order to eliminate the effect of any differences between the two sections of casing delimited by the electrodes a circuit connec-, ted to the electrodes and forming a Wheatstone bridge is balanced with said sections of casing constituting two of the resistances in said Wheatstone bridge circuit.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 18, 1994 and granted May 7, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 18, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 18, 2016.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.