| 摘要 |
A tool for connection in a wellbore drill string for maintaining penetration of a drilling bit attached to the drill string when the drill string becomes stuck or hung up during drilling operations. The tool has a telescoping outer member and inner member which form an annular chamber between them which contains a plurality of springs that are selected to provide a desired amount of contraction of the tool when a predetermined axial compressive load is applied through the tool to the drilling bit. The tool also includes interlocking splines on the outer member and the inner member which inhibit rotational movement of the outer member and inner member relative to each other, and the chamber is filled with hydraulic fluid which is pressurized to the hydrostatic pressure of the wellbore adjacent the tool by a floating piston which is movably located in the chamber. In operation, the tool contracts when an axial compressive load is applied through the tool during drilling operations. If the axial compressive load is decreased due to sticking or hangup of the drilling string, the springs operate to extend the tool, thus maintaining a force on the drilling bit which causes the drilling bit to maintain an amount of penetration in the wellbore.
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