Slack removal apparatus

Claim 1

In apparatus for maintaining a predetermined stress in a running-in string disposed in a well bore underlying a body of water and which is supported by a rig including a derrick and a deck mounted on a barge, or the like, floating in the body of water and having a block and tackle, including a crown block and a traveling block with lines therebetween, at least one line extending from the crown block to a support at a lower Portion of the rig, means operatively connecting the running-in string to the traveling block, and means for maintaining a predetermined stress in the running-in string, the improvement which comprises means attached to the rig and operatively connected to the line extending from the crown block to the support and separate from the crown block and support for maintaining a substantially constant pull on the line to remove slack from the line as the predetermined stress maintaining means compensates for movement of the barge which comprises: a. a cylinder; b. a piston slidable relatively in the cylinder and constituting with the cylinder a piston-cylinder assembly; c. first means attaching the piston-cylinder assembly to the rig; d. second means slidably connecting the piston-cylinder assembly to the line, one of the first and second means being attached to the piston and the other to the cylinder so that the piston is moveable longitudinally along the cylinder; and e. means for maintaining fluid under substantially constant pressure in the cylinder and on the piston as the piston and cylinder move longitudinally relative to each other, and whereby a substantially constant pull is maintained on the line to remove slack from the line as the predetermined stress maintaining means compensates for movement of the barge, and including the following additional elements: f. means for constantly feeding fluid under pressure to the cylinder; g. means for constantly conducting the fluid from the cylinder; and h. a flow restricting instrumentality in the conducting means for creating a back pressure in the fluid in the cylinder.