Patents by Inventor Daniel J. Campbell

Daniel J. Campbell 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).

  • Method and apparatus for maintaining electric cable inside drill pipe
    Patent number: 4098342
    Abstract: An insulated electric conductor employed in a tubular drill string to transmit electric energy between subsurface and surface locations is arranged within the drill string in a convoluted configuration to provide an excess length of conductor. The convoluted conductor is prevented from entangling during drilling by rotation limiting assemblies mounted in the drill string over a selected interval.
    Type: Grant
    Filed: May 25, 1977
    Date of Patent: July 4, 1978
    Assignee: Exxon Production Research Company
    Inventors: Leon H. Robinson, Jerry M. Speers, Adelbert Barry, Daniel J. Campbell