Liner/casing buoyancy arrangement, method and system

Abstract

An arrangement for a buoyant liner or casing string including a shoe plug affixed to the string and configured to hold a pressure differential from a higher pressure outside of the string to a lower pressure inside of the string and to unseat upon a pressure differential of a higher pressure inside of the string to a pressure outside of the string.

1 . An arrangement for a buoyant liner or casing string comprising:
 a shoe plug affixed to the string and configured to hold a pressure differential from a higher pressure outside of the string to a lower pressure inside of the string and to unseat upon a pressure differential of a higher pressure inside of the string to a pressure outside of the string.   
     
     
         2 . The arrangement as claimed in  claim 1 , wherein the shoe plug comprises a cone and a seat. 
     
     
         3 . The arrangement as claimed in  claim 2 , wherein at least one of the cone and seat comprise a degradable material. 
     
     
         4 . The arrangement as claimed in  claim 1  further including a plug affixed to the string in spaced relationship to the shoe plug to create a pressure chamber of lower pressure than ambient hydrostatic pressure when run in a borehole. 
     
     
         5 . The arrangement as claimed in  claim 4 , wherein the pressure chamber is an atmospheric pressure chamber. 
     
     
         6 . The arrangement as claimed in  claim 4 , wherein the plug comprises a disappear on demand material. 
     
     
         7 . The arrangement as claimed in  claim 6  wherein the plug includes a trigger. 
     
     
         8 . The arrangement as claimed in  claim 7  wherein the trigger is an igniter. 
     
     
         9 . A borehole system comprising:
 a borehole in a subsurface formation;   a string in the borehole;   a shoe plug affixed to an end of the string, the shoe plug configured to hold a pressure differential from a higher pressure outside of the string to a lower pressure inside of the string and to unseat upon a pressure differential of a higher pressure inside of the string to a pressure outside of the string.   
     
     
         10 . The borehole system as claimed in  claim 9  further comprising a plug disposed in the string spaced from the shoe plug to create a pressure chamber. 
     
     
         11 . The borehole system as claimed in  claim 10 , wherein the plug comprises disappear on demand material and a trigger. 
     
     
         12 . A method for managing a borehole comprising:
 affixing a shoe plug to a string, the shoe plug configured to hold a pressure differential from a higher pressure outside of the string to a lower pressure inside of the string and to unseat upon a pressure differential of a higher pressure inside of the string to a pressure outside of the string;   running the string to depth;   applying pressure to the inside of the spring to exceed pressure outside of the string; and   unseating the shoe plug to allow full bore flow in the string.   
     
     
         13 . The method as claimed in  claim 12  further including:
 affixing a plug to the string spaced from the shoe plug to create a pressure chamber therebetween. 
 
     
     
         14 . The method as claimed in  claim 13  further including triggering the plug to disappear. 
     
     
         15 . The method as claimed in  claim 12  further including degrading the shoe plug. 
     
     
         16 . A casing/liner string buoyancy arrangement comprising:
 3 or more seals in the string spaced apart from one another;   a chamber defined between each two adjacent seals constituting a plurality of chambers, the plurality of chambers and contents therewithin having a lower specific gravity than borehole fluid anticipated to be encountered by the arrangement, during use.   
     
     
         17 . The arrangement as claimed in  claim 16  wherein one or more of the seals comprises a degradable material. 
     
     
         18 . The arrangement as claimed in  claim 16  wherein one or more of the seals comprises a disappear-on-demand material. 
     
     
         19 . The arrangement as claimed in  claim 16  wherein at least one of the plurality of chambers contains a gas or fluid. 
     
     
         20 . The arrangement as claimed in  claim 16  wherein the seals are individually addressable to unseal such that fluid exchange in a specific one or more of the plurality of chambers is enabled.