Well system with degradable plug

Abstract

A downhole assembly is disclosed. The downhole assembly includes a tube disposed in a wellbore, and a shroud coupled to and disposed around the circumference of the tube to form an annulus between an inner surface of the shroud and an outer surface of the tube. The downhole assembly further includes a flow control device disposed in the annulus, and a degradable plug disposed in the annulus and positioned to prevent fluid flow between the annulus and the tube.

1 . A downhole assembly, comprising:
 a tube disposed in a wellbore;   a shroud coupled to and disposed around the circumference of the tube to form an annulus between an inner surface of the shroud and an outer surface of the tube;   a flow control device disposed in the annulus; and   a degradable plug disposed in the annulus and positioned to prevent fluid flow between the annulus and the tube.   
     
     
         2 . The downhole assembly of  claim 1 , further comprising a screen coupled to and disposed uphole from the shroud and coupled to and disposed around the circumference of the tube such that an annulus is formed between an inner surface of the screen and the outer surface of the tube. 
     
     
         3 . The downhole assembly of  claim 1 , wherein the degradable plug is positioned in-line with and adjacent to or axially displaced from the flow control device. 
     
     
         4 . (canceled) 
     
     
         5 . The downhole assembly of  claim 1 , wherein the degradable plug is engaged with the shroud and the tube to form a fluid and pressure tight seal. 
     
     
         6 . The downhole assembly of  claim 1 , wherein the degradable plug is positioned in an opening formed in a sidewall of the tube and engaged with the tube to form a fluid and pressure tight seal to prevent fluid flow between the annulus and the tube. 
     
     
         7 . The downhole assembly of  claim 1 , wherein the degradable plug is formed of a composition that degrades within the annulus within a predetermined time of exposure to a particular fluid. 
     
     
         8 . The downhole assembly of  claim 7 , wherein the degradable plug comprises
 a coating formed around the degradable plug that temporarily protects the degradable plug from exposure to the particular fluid.   
     
     
         9 . The downhole assembly of  claim 1 , wherein the degradable plug comprises a first composition imbedded with particles of a second composition to form a galvanic cell. 
     
     
         10 . The downhole assembly of  claim 1 , wherein the degradable plug comprises:
 a shell including a channel extending there through; and   a degradable core disposed within the channel and formed of a composition that degrades within the annulus within a predetermined time of exposure to a particular fluid.   
     
     
         11 . The downhole assembly of  claim 1 , wherein the degradable plug comprises:
 a shell including a channel extending there through;   a degradable core disposed within the shell and formed of a composition that degrades within the annulus within a predetermined time of first exposure to a particular fluid; and   a rupture disk that temporarily protects the degradable plug from exposure to the particular fluid, the rupture disk formed of a material that fractures when exposed to a threshold pressure.   
     
     
         12 . The downhole assembly of  claim 1 , wherein the degradable plug comprises:
 a shell including:
 a first channel extending radially there through; and 
 a second channel extending axially from an outer surface of the shell to the first channel; and 
   a degradable core disposed within the second channel and formed of a composition that degrades within the annulus within a predetermined time of exposure to a particular fluid.   
     
     
         13 . (canceled) 
     
     
         14 . A well system comprising:
 a production string; and   a downhole assembly coupled to and disposed downhole from the production string, the downhole assembly comprising:
 a tube; 
 a shroud coupled to and disposed around the circumference of the tube to form an annulus between an inner surface of the shroud and an outer surface of the tube; 
 a flow control device disposed in the annulus; and 
 a degradable plug disposed in the annulus and positioned to prevent fluid flow between the annulus and the tube. 
   
     
     
         15 . The well system of  claim 14 , wherein the downhole assembly further comprises a screen coupled to and disposed uphole from the shroud and coupled to and disposed around the circumference of the tube such that an annulus is formed between an inner surface of the screen and the outer surface of the tube. 
     
     
         16 . The well system of  claim 14 , wherein the degradable plug is positioned in-line with and adjacent to or axially displaced from the flow control device. 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . The well system of  claim 14 , wherein the degradable plug is positioned in an opening formed in a sidewall of the tube and engaged with the tube to form a fluid and pressure tight seal to prevent fluid flow between the annulus and the tube. 
     
     
         20 . The well system of  claim 14 , wherein the degradable plug is formed of a composition that degrades within the annulus within a predetermined time of exposure to a particular fluid. 
     
     
         21 . The well system of  claim 20 , wherein the degradable plug comprises
 a coating formed around the degradable plug that temporarily protects the degradable plug from exposure to the particular fluid.   
     
     
         22 . (canceled) 
     
     
         23 . The well system of  claim 14 , wherein the degradable plug comprises:
 a shell including a channel extending there through; and   a degradable core disposed within the channel and formed of a composition that degrades within the annulus within a predetermined time of exposure to a particular fluid.   
     
     
         24 . The well system of  claim 14 , wherein the degradable plug comprises:
 a shell including a channel extending there through;   a degradable core disposed within the shell and formed of a composition that degrades within the annulus within a predetermined time of first exposure to a particular fluid; and   a rupture disk that temporarily protects the degradable plug from exposure to the particular fluid, the rupture disk formed of a material that fractures when exposed to a threshold pressure.   
     
     
         25 . The well system of  claim 14 , wherein the degradable plug comprises:
 a shell including:
 a first channel extending radially there through; and 
 a second channel extending axially from an outer surface of the shell to the first channel; and 
   a degradable core disposed within the second channel and formed of a composition that degrades within the annulus within a predetermined time of exposure to a particular fluid.   
     
     
         26 . (canceled) 
     
     
         27 . A method of temporarily preventing fluid flow between a production string and a wellbore, comprising:
 positioning a degradable plug in a wellbore such that the plug prevents fluid flow between a production string and a wellbore; and   triggering a chemical reaction that causes the degradable plug to degrade to a point where fluid flow between the production string and the wellbore is permitted.   
     
     
         28 . The method of  claim 27 , wherein the degradable plug is positioned in fluid communication with a flow control device. 
     
     
         29 . The method of  claim 28 , wherein the degradable plug is positioned in-line with and adjacent to or axially displaced from the flow control device. 
     
     
         29 . (canceled) 
     
     
         30 . The method of  claim 27 , wherein the chemical reaction is triggered by exposure of the degradable plug to a particular fluid for an amount of time exceeding a threshold time. 
     
     
         31 . The method of  claim 27 , wherein triggering the chemical reaction comprises removing a protective coating formed around the degradable plug to expose the degradable plug to a particular fluid. 
     
     
         32 . The method of  claim 31 , wherein removing the protective coating comprises exposing the degradable plug to a threshold temperature that causes the protective coating to melt or a threshold pressure that causes the protective coating to fracture. 
     
     
         33 . (canceled) 
     
     
         34 . The method of  claim 27 , wherein the degradable plug degrades into particles small enough such that the particles do not impede fluid flow. 
     
     
         35 . (canceled) 
     
     
         36 . The method of  claim 27 , wherein triggering the chemical reaction comprises rupturing a rupture disk to expose a core of the degradable plug to a particular fluid for an amount of time exceeding a threshold time.