Expired Canadian patentCanada
Method and apparatus for preventing buckling of a well casing
CA 919085 A · Owner: Shell Internationale Research Maatschappij, N.V. · Inventors: Leo P. Broussard
Overview
Drawings and full text
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordRead 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
- Granted January 16, 1973. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended January 16, 1990.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Filed—
GrantedJanuary 16, 1973
Term endedJanuary 16, 1990
Patent numberCA 919085 A
Classification (IPC)E21B33/14 +1 more
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.