Patents by Inventor H. Douglas Dahl

H. Douglas Dahl 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).

  • Pretreatment for fracturing coal seams
    Patent number: 4283089
    Abstract: A pretreatment for use in fracturing coal seams to increase gas permeability of the seams. The pretreatment involves injecting a material capable of swelling coal into a coal seam prior to fracturing the coal seam. The pretreatment material swells the coal and closes the natural cleats therein, enhancing the effectiveness of the subsequent fracturing step.
    Type: Grant
    Filed: June 12, 1980
    Date of Patent: August 11, 1981
    Assignee: Conoco, Inc.
    Inventors: Raymond L. Mazza, H. Douglas Dahl, Ronald W. Umphrey
  • Borehole pressure cell
    Patent number: 4030345
    Abstract: A device and method for determining strength properties of a subterranean formation. The device is insertable into a borehole formed in the formation, and includes a pair of inflatable semi-cylindrical members mounted on a shaft. The inflatable members when pressurized exert radial force in all directions except along the plane between the members, with the result that a higher parting force is exerted on the formation perpendicular to the plane between the members than across any other plane through the axis of the device.
    Type: Grant
    Filed: August 13, 1976
    Date of Patent: June 21, 1977
    Assignee: Continental Oil Company
    Inventors: Tibor O. Edmond, H. Douglas Dahl