Patent ID: 6244350
Filing Date: 2001-06-12
Classification: E21B

Abstract:
An apparatus for launching at least one plug into a tubular in a wellbore, said apparatus comprising a hollow upper section and a hollow lower section, said hollow upper section comprising at least first and second upper ports (12, 13) longitudinally spaced therein, said second upper port (13) being disposed above said first upper port (12), a landing seat (7) between said hollow upper section and said hollow lower section, and a first fluid displaceable member (4) retained below said second upper port (13), said hollow lower section adapted to retain at least one plug (8) and comprising at least a first lower port (10) thereabove and a landing collar (6) for said fluid displaceable member (4), the arrangement being such that in use, when the apparatus is installed at the top of a liner and lowered into the wellbore, and a first dart lands on said landing seat (7) blocking said first upper port (12), creating a fluid pressure differential around said first fluid displacement member (4) and through said second upper port (13), the fluid pressure differential being used to displace said first fluid displacement member (4) to said landing collar (6), allowing the fluid pressure differential about said plug through said first lower port (10) to launch said plug,said apparatus further comprising a third upper port (14) in said hollow upper section above said second upper port (13) and a second fluid displaceable member (5) retained below said third port (14) said hollow lower section adapted to retain a second plug (9), and comprising a second lower port (11) thereabove, so that in use, when a second dart (16) lands on said first dart (15) blocking said second upper port it allows a fluid pressure differential to be created about said second fluid displaceable member (5) through said second upper port which displaces said second fluid displaceable member (5) to said first fluid displaceable member blocking said first lower port (10), allowing the fluid pressure differential about said second plug (9) through said second lower port to launch said second plug.