Apparatus and method for temporarily plugging a tubular

A method for controlling the pressure at which a fluid is introduced through a tubular, the method comprising:

• (a) securing first and second temporary plugs to a tubular, said plugs being spaced apart so as to define a fluid tight chamber therebetween which is filled with a first fluid at a known pressure, said first plug capable of opening upon application of a predetermined pressure and said second plug capable of opening upon application of a pressure which is less than said predetermined pressure and greater than said known pressure;
• (b) introducing a second fluid into said tubular;
• and
• (c) applying a predetermined pressure to said second fluid thereby opening said first plug and subsequently opening said second plug, so as to permit said second fluid to flow past said spaced apart locations.

A method for controlling the pressure at which a fluid is introduced into a subterranean well through a tubular, the method comprising:

• (a) securing first and second temporary plugs to a tubular, said plugs being spaced apart so as to define a fluid tight chamber therebetween which is filled with a first fluid at a known pressure, said first plug capable of opening upon application of a predetermined pressure and said second plug capable of opening upon application of a pressure which is less than said predetermined pressure and greater than said known pressure;
• (b) introducing a second fluid into said tubular;
• and
• (c) applying a predetermined pressure to said second fluid thereby opening said first plug and subsequently opening said second plug, so as to permit said second fluid to flow past said spaced apart locations within a subterranean well.

A method for introducing a second fluid into a subterranean wellbore and for introducing a third fluid into the subterranean wellbore at a controlled pressure, the method comprising:

• (a) securing first and second temporary plugs to a tubular, said plugs being spaced apart so as to define a fluid tight chamber therebetween which is filled with a first fluid at a known pressure, said first plug capable of opening upon application of a predetermined pressure said second plug capable of opening upon application of a pressure which is less than said predetermined pressure and greater than said known pressure, and the first plug having a channel at least partly therein providing for fluid communication between an interior portion of said tubular above said first plug and said well outside said tubular;
• (b) introducing a second fluid into said tubular at a pressure less than the predetermined pressure and allowing the second fluid to flow through said channel and into said well outside said tubular;
• (c) introducing a third fluid into said tubular;
• and
• (d) applying a predetermined pressure to said third fluid thereby opening said first plug and subsequently opening said second plug, so as to permit said second fluid to flow past said spaced apart locations within a subterranean well.