Patents Assigned to Enterra Oil Field Rental
  • Patent number: 5639135
    Abstract: A fishing spear for retrieving a fish from a wellbore comprises a mandrel fixedly secured to an upper sub, a collet assembly telescopically surrounding the mandrel and a support sleeve telescopically surrounding the mandrel and positioned between the mandrel and the collet assembly. An expandable fluid cavity is formed between a portion of the facing surfaces of the support sleeve and the mandrel. A coil spring, which is disposed between the support sleeve and the upper sub, downwardly biases the support sleeve so that it rests against a projecting head at the bottom of the mandrel when fluid pressure is not applied to the expandable cavity. The collet assembly includes a plurality of collet fingers, each having a collet head at the end thereof. The collet fingers are naturally inwardly radially biased in the direction of the mandrel. When the support sleeve rests on the projecting head, the collet heads are radially outwardly displaced or wedged.
    Type: Grant
    Filed: November 23, 1994
    Date of Patent: June 17, 1997
    Assignee: Enterra Oil Field Rental
    Inventor: Robert S. Beeman