Method and apparatus to receive and transmit signals in wells, especially horizontal wells

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 November 28, 1989 and granted August 29, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 28, 2009.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 28, 2011.
• We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.