| 摘要 |
<p>SINGLE ACTING HYDRAULIC FISHING JAR a single acting hydraulic fishing jar is disclosed for use in a tubular drilling string for applying upward jarring forces for dislodging a "fish" from a well. The jar is adapted to be run into a well on a drill string and connected to a fishing tool in the well bore. This jar comprises outer and inner housing members positioned in telescoping relation for longitudinal movement of one relative to the other and having a hammer member on one and an anvil member on the other. the housing members enclose a chamber adapted to contain a fluid for controlling application of jarring forces. A sliding seal closes one end of the chamber and supports the inner housing member, or mandrel, for sliding movement in the outer housing member. A piston is positioned in spaced relation to the sliding seal for movement of each relative to the other in the hydraulic fluid chamber. The piston is arranged so that movement of one housing relative to the other in one direction will move the piston toward the sliding seal. The chamber between the piston and the sliding seal has an outlet controlled by a valve member supported for sliding movement on the mandrel. Predetermined relative movement of the housing members engages the valve member to move it to open position to permit flow of fluid from the fluid chamber to substantially eliminate the resistance to further movement of the housing members and thus permit movement of a hammer member carried by the mandrel into engagement with an anvil member carrier on the outer housing with an impact force.</p> |
