Method and device for stimulating an underground zone by deffered injection of fluid coming from a surrounding zone along fractures made from a drain bored in a intermediate layerof low permeability

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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 December 28, 1990 and granted January 22, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 28, 2010.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 28, 2012.
• We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.