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Expired Canadian patentCanada

Basic oil well cement

CA 1087385 A · Owner: Uss Engineers And Consultants, Inc. · Inventors: Tresouthick, Stewart W.; Maravilla, Sam

CIPO record

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

A versatile hydraulic basic oil well cement compatible, with retarders and most common field additives and able to perform its intended function over a wide variety of downhole conditions particularly temperature and pressure, comprises a common moderate or high sulfate resistant clinker and a weight ratio of calcium sulfate hemihydrate to insoluble anhydrite of 20:80 to 45:55. It can be made either by adding controlled amounts of gypsum and insoluble anhydrite to the grinding circuit or by blending ground hemihydrate and insoluble anhydrite to ground clinker.

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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

  • Granted October 14, 1980. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended October 14, 1997.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJune 19, 1978
GrantedOctober 14, 1980
Term endedOctober 14, 1997
Patent numberCA 1087385 A
Classification (IPC)C09K8/05 +1 more

Timeline

Timeline From CIPO dates

1979198119831985198719891991199319951997Application filedJune 19, 1978Patent grantedOct 14, 1980Term endedOct 14, 1997

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.