Patents by Inventor John R. Doan

John R. Doan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Anchorable pack-off assembly
    Patent number: 3945774
    Abstract: A pack-off assembly provides a dual tubing dump for a well, for example an oil well, includes a pack-off assembly which forms, divides and fluidically seals upper and lower pumping chambers to provide essentially twice the ordinary fluid flow from a well.
    Type: Grant
    Filed: March 25, 1974
    Date of Patent: March 23, 1976
    Inventor: John R. Doan