| 摘要 |
An apparatus for jarring a portion of drill string lodged within a borehole, by jarring downhole using tension only, including a first member for attaching a first lower end of the apparatus to the upper end of the lodged tool or pipe through a threadable attachment; a second member for attaching a second end of the apparatus to a drill string on its upper end portion; a third anvil or hammer member which is triggered by spring having stored compressional force transferred by tension from the drill string to the apparatus when the drill string is pulled upward. There is also provided an actuator for rapidly releasing the tension force provided by the spring downward onto the stuck pipe in order to provide an impacting, downward force onto the pipe in an effort to dislodge the pipe. There is further provided a slow release mechanism for slowly releasing the tension force stored by the spring in the event the tool is not fired downhole.
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