Abstract: There is disclosed a hydraulic jarring device in which an impediment mechanism for controlling the movement of a mandrel with respect to a barrel is exposed to a fluid pressure which is significantly reduced from that pressure generated by the tensional load applied to the jarring device by the hoisting apparatus used to recover an object lodged within a well bore. The impediment mechanism, in one embodiment, is actuated by one or more hydraulically operated plungers slidably mounted within the housing of the jarring device. The plungers cooperate with a control sleeve whose movement is in turn controlled by a metering valve operating at a pressure significantly less than that above the plungers, and having an effect on movement of the sleeve inverse to the tension generated by the hoisting apparatus. The metering valve, in one embodiment, comprises a movable helical plug having a needle nose which associates with a valve seat to control fluid flow.

Abstract: Well bore pressure is utilized to develop an activating pressure during telescoping movement between an outer drill string and an inner mandrel for momentarily locking the mandrel to the drill string. Locking is effected through laterally displaceable mechanical elements carried by the mandrel and held engaged for a predetermined period of time during which an axial tension is applied to the mandrel. A control circuit independent of the amount of axial tension load provides for sudden release of the locking elements at the end of said predetermined period which results in free travel of the mandrel to an impact position to deliver a jarring blow to the drill string for dislodging stuck elements or junk in the well bore.

Abstract: Disclosed is a tool for injecting into or washing perforations in a cased well bore. The tool includes an outer housing and an inner mandrel with a fluid passage therebetween. Perforations are cleaned by discharging fluid from the passage into a region between closely spaced cups for maintaining pressure. Also disclosed is a valve system whereby the washing of perforations can be performed either by pumping fluid down the casing or the tubing string. The washing fluid discharged between the cups enters the perforations and is circulated behind the casing until reentering the casing bore through other perforations either above or below the cups. The fluid is returned to the well surface through the tubing by entering either from the tool bottom or through ports in the housing which are in communication with the inner mandrel.

Abstract: An apparatus is disclosed for packing the annular space between the exterior of a sand screen or liner and the well casing or bore with accurately sized sand or gravel to prevent the intrusion of well sands into the well casing or bore. The apparatus includes a hydraulically actuated fluid diverting means and release mechanism to open diverting passageways and separate the sand screen or liner assembly from the run-in tool before introduction of the sized sand or gravel and without rotation of the run-in tool with respect to the sand screen or liner. The diverting means is capable of being closed at the completion of the injection process to facilitate the resumption of production from the well without the necessity of pulling the assembly out of the well bore for closing the diverting means thereby providing a novel method for gravel packing or sand packing a well.