| 摘要 |
A jarring and bumping tool is provided, having a mandrel telescopically received within a barrel for relative longitudinal movement. Upper and lower seals form an oil- containing annular space therebetween. The mandrel carries a free-floating annular primary piston which sealably engages a reduced-diameter piston fitting section of the barrel when passing therethrough. The mandrel also carries a secondary cylinder assembly with a transverse top wall and a downwardly extending annular secondary cylinder beneath the primary piston, forming a piston chamber between the mandrel and secondary cylinder assembly. The mandrel also carries a spring which biases a free-floating annular secondary piston upwards into the piston chamber. A port through the top wall of the cylindrical member provides fluid communication between the annular space and the piston chamber. Thus, when the mandrel is pulled upwards the primary piston seals against the piston fitting section, oil in the annular space is compressed and forced through the port and into the piston chamber against the secondary piston to compress the spring, and the drill string is stretched. When the primary piston clears the piston fitting section, fluid moves rapidly around the primary piston, the mandrel extends, and impact faces connect to deliver a jarring stroke upwards.
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