Patents by Inventor George C. Duncan

George C. Duncan 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).

  • Patent number: 7543651
    Abstract: The present invention generally relates to a non-elastomeric cement through tubing retrievable safety valve configured to control fluid flow through a production tubing string. In one aspect, a valve for use in a wellbore is provided. The valve includes a tubular body. The valve further includes a flow tube having a bore therethrough, wherein the flow tube is disposed in the tubular body to form an annular area therebetween. The valve further includes a flapper movable between an open position and a closed position in response to the movement of the flow tube. Additionally, the valve includes a sealing system constructed and arranged to substantially isolate the annular area from the bore, thereby substantially eliminating the potential of contaminants in the bore from entering into the annular area. In another aspect, a method of controlling fluid in a wellbore is provided.
    Type: Grant
    Filed: October 21, 2005
    Date of Patent: June 9, 2009
    Assignee: Weatherford/Lamb, Inc.
    Inventors: Roddie R. Smith, Nathaniel H. Wagner, George C. Duncan
  • Patent number: 7314091
    Abstract: A subsurface safety valve is first provided. The safety valve generally comprises a tubular housing, an isolation sleeve disposed within an inner diameter of the tubular housing, with the isolation sleeve and the tubular body forming an annular area there between, a flow tube movably disposed along a portion of the annular area, and a flapper. The flapper is pivotally movable between an open position and a closed position in response to longitudinal movement of the flow tube in order to open and close the valve. Preferably, the annular area is isolated from an inner diameter of the isolation sleeve in the open position. A method is also provided that allows for a cementing operation to be performed through an open safety valve.
    Type: Grant
    Filed: May 25, 2004
    Date of Patent: January 1, 2008
    Assignee: Weatherford/Lamb, Inc.
    Inventors: Nathaniel Heath Wagner, George C. Duncan, Roddie R. Smith