Apparatus and method for launching plugs in cementing operations

摘要

An apparatus for use in launching cement plugs in a well cementing operation, comprising: a cylinder (130); a piston (110) slideably received in the bore of the cylinder; and an actuator, operable by the piston, for launching a plug from the apparatus into the well; wherein the cylinder has a resiliently mounted latching member (132) positioned in the wall thereof and biased to project into the bore of the cylinder; and the piston has a profiled outer surface defining a recess (114) into which the latching member (132) can project to hold the piston in position in the cylinder.

主权项

1. An apparatus for use in launching cement plugs in a well cementing operation, comprising:
a cylinder having a bore and an inner wall; a drive piston slideably received in the bore of the cylinder; and a main rod, operable by the piston, for launching a plug from the apparatus into the well; wherein:
the apparatus is placed inside a tubular body; the cylinder has a resiliently mounted latching member positioned along the inner wall and biased to project into the bore of the cylinder; the drive piston has a profiled outer surface with angled surfaces defining a recess into which the latching member can project to hold the piston in a position in the cylinder;
the angled surfaces of the drive piston are arranged such that a first maximum force is required to move the piston such that the latching member passes over a first maximum diameter of the piston and engages in the recess, and a second maximum force is required to move the piston such that the latching member leaves the recess, passes over a second maximum diameter of the piston and completely releases the piston; andthe second maximum diameter is larger than the first maximum diameter.