Plug injection method and apparatus

Apparatus for use in launching a device plug into a well conduit, comprising:

• a tubular body having a central passageway and means at its opposite ends for connecting said body in pipe string;
• inlet means through the wall of said body to enable a fluid to be pumped through said passageway;
• cylinder means attached to said body and inclining upward and outward thereof, said cylinder means being adapted to receive a device that is to be moved into said passageway and down into said pipe string;
• piston means in said cylinder means movable from an outer position to an inner position therein for moving said device into said passageway;
• gate means on said cylinder means for permitting and preventing movement of said device;
• and remotely and selectively operable means for actuating said piston means and said gate means.

A method of injecting an operating device into the passageway of a body having its upper end coupled to an upper pipe member and its lower end coupled to a lower pipe member and allowing rotation of the pipe members relative to said body, comprising the steps of:

• providing a pressure responsive sleeve that is slidably splined to said upper member for movement between upper and lower positions;
• biasing said sleeve toward said upper position;
• applying fluid pressure to said sleeve to shift it to said lower position;
• automatically coupling said sleeve to said lower pipe member in said lower position to transmit rotation on said upper pipe member to said lower pipe member via said sleeve;
• and injecting an operating device into said passageway when said sleeve is in said upper position.

A method of sequentially launching upper and lower cementing plugs that are releasably connected to one another and to a tubular member above said upper cementing plug, comprising the steps of:

• providing releasing seats in each of said plugs, said seat in said lower plug having a lesser internal dimension than the seat in said upper plug:
• pumping a first releasing member through said upper plug and into the releasing seat in said lower plug;
• releasing said lower plug from said upper plug when said first releasing member seats in said releasing seat on said lower plug to enable said lower plug to move downward in a well conduit ahead of said first plug;
• pumping a second releasing member into said releasing seat in said upper plug;
• and releasing said upper plug from said tubular member when said second releasing member seats in said releasing seat in said upper plug to enable said upper plug to move downward in the well conduit.