LAUNCHING TOOL FOR OBJECTS DOWNHOLE

The invention comprises a tool for launching objects downhole, such as one or more plugs in a desired sequence. The movements leading to the release of the individual plugs are regulated by virtue of displacement of o il through at least one orifice. The wiper plugs are retained in the tool until such time as they are physically displaced beyond the lower end of the tool. The biased retainers holding the plugs within the tools are released upon a predetermined movement of the plugs beyond the lower end of the tool. If the retaining mechanism for the plug does not automatically release upon sufficient extension of the wiper plug from the tool, a pressure assist can be used to launch any given plug. The darts used to move an actuating piston to release the plugs are separated from the plugs and retained in the tool so that they do not need to be drilled out later.