Method and apparatus for temporarily maintaining a downhole foam element in a compressed state

Abstract

The present invention is directed to a degradable wrap and method for temporarily maintaining a downhole foam element in a compressed state. The degradable wrap is fitted around the foam element and temporarily maintains the foam element in a compressed state against an outer surface of a downhole sand control device. It is provided to keep the foam element in the compressed state while a production assembly comprising the downhole sand control device and foam element mounted thereon is placed downhole in a well bore adjacent to a production zone. The degradable wrap is permeable to the production fluid and degrades over time. Once the degradable wrap has degraded the foam element fills the annulus between the production screen and casing string or well bore wall. The foam element acts to inhibit the flow of water along the annulus and is useful in zone isolation.

1 . A method for temporarily maintaining a compressible foam element in a compressed state against an outer surface of a downhole sand control device, comprising the steps of: 
 (a) installing a production assembly downhole within a casing string or well bore, the production assembly comprising a degradable wrap securely fitted around the compressible foam element so as to cause the compressible foam element to assume a compressed configuration against the downhole sand control device; and    (b) degrading the degradable downhole wrap thereby causing the compressible foam element to expand into contact with the casing string or well bore.    
   
   
       2 . The method according to  claim 1 , further comprising the step of isolating a a section of the production assembly.  
   
   
       3 . The method according to  claim 2 , wherein the isolating step comprises the steps of installing an isolation pipe having a top end and a bottom end inside the production assembly and sealing the isolation pipe to the production assembly.  
   
   
       4 . The method according to  claim 3 , wherein the step of installing the isolation pipe inside the production assembly is performed after the step of installing the production assembly downhole in the casing string or well bore and production has been flowing for a period of time.  
   
   
       5 . The method according to  claim 3 , wherein a coil tubing is employed to install the isolation pipe inside of the production assembly and to seal the top and bottom ends of the isolation pipe to the production assembly.  
   
   
       6 . The method according to  claim 1 , wherein the degradable wrap is biodegradable and gradually degrades by thermal hydrolysis in the presence of the aqueous solution.  
   
   
       7 . The method according to  claim 6 , wherein the biodegradable wrap is in the form of a string or tape, which is helically wound around the compressible foam element.  
   
   
       8 . The method according to  claim 7 , wherein the biodegradable wrap is formed into a tubular sheath.  
   
   
       9 . The method according to  claim 8 , wherein the biodegrable tubular sheath is formed of a woven cloth.  
   
   
       10 . The method according to  claim 1 , wherein the degradable wrap comprises a degradable polymer selected from the group consisting of homopolymers, random, block, graft, and star- and hyper-branched aliphatic polyesters.  
   
   
       11 . The method according to  claim 1 , wherein the degradable wrap comprises a degradable polymer selected from the group consisting of polysaccharides; chitins; chitosans; proteins; aliphatic polyesters; poly(lactides); poly(glycolides); poly(ε-caprolactones); poly(hydroxybutyrates); poly(anhydrides); aliphatic polycarbonates; poly(orthoesters); poly(amino acids); poly(ethylene oxides); and polyphosphazenes.  
   
   
       12 . The method according to  11 , wherein the degradable wrap comprises an aliphatic polyester having the general formula of repeating units shown below:  
     
       
         
         
             
             
         
       
     
     where n is an integer between 75 and 10,000 and R is selected from the group consisting of hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatoms, and mixtures thereof.  
   
   
       13 . The method according to  claim 11 , wherein the degradable wrap further comprises a plasticizer.  
   
   
       14 . The method according to  claim 13 , wherein the plasticizer comprises a derivative of oligomeric lactic acid, selected from the group defined by the formula:  
     
       
         
         
             
             
         
       
     
     where R is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R is saturated, where R′ is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R′ is saturated, where R and R′ cannot both be hydrogen, where q is an integer and 2≦q≦75; and mixtures thereof.  
   
   
       15 . The method according to  claim 1 , wherein the degradable wrap is permeable enabling a production fluid to pass through the compressible foam element and the sand control device.  
   
   
       16 . A production assembly, comprising: 
 a base pipe;    a sand control device incorporated within, or mounted to, the base pipe;    a compressible foam element mounted to the sand control device; and    a degradable wrap securely fitted around the compressible foam element so as to cause the compressible foam element to assume a compressed configuration.    
   
   
       17 . The production assembly according to  claim 16 , wherein the degradable wrap is biodegradable and gradually degrades by thermal hydrolysis in the presence of an aqueous solution.  
   
   
       18 . The production assembly according to  claim 17 , wherein the biodegradable wrap is in the form of a string or tape, which is helically wound around the compressible foam.  
   
   
       19 . The production assembly according to  claim 17 , wherein the biodegradable wrap is formed into a tubular sheath.  
   
   
       20 . The production assembly according to  claim 19 , wherein the biodegrable tubular sheath is formed of a woven cloth.  
   
   
       21 . The production assembly according to  claim 16 , wherein the degradable wrap comprises a degradable polymer selected from the group consisting of homopolymers, random, block, graft, and star- and hyper-branched aliphatic polyesters.  
   
   
       22 . The production assembly according to  claim 16 , wherein the degradable wrap comprises a degradable polymer selected from the group consisting of polysaccharides; 
 chitins; chitosans; proteins; aliphatic polyesters; poly(lactides); poly(glycolides); poly(ε-caprolactones); poly(hydroxybutyrates); poly(anhydrides); aliphatic polycarbonates; poly(orthoesters); poly(amino acids); poly(ethylene oxides); and polyphosphazenes.    
   
   
       23 . The production assembly according to  claim 22 , wherein the degradable wrap comprises an aliphatic polyester having the general formula of repeating units shown below:  
     
       
         
         
             
             
         
       
     
     where n is an integer between 75 and 10,000 and R is selected from the group consisting of hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatoms, and mixtures thereof.  
   
   
       24 . The production assembly according to  claim 22 , wherein the degradable wrap further comprises a plasticizer.  
   
   
       25 . The production assembly according to  claim 24 , wherein the plasticizer comprises a derivative of oligomeric lactic acid, selected from the group defined by the formula:  
     
       
         
         
             
             
         
       
     
     where R is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R is saturated, where R′ is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R′ is saturated, where R and R′ cannot both be hydrogen, where q is an integer and 2≦q≦75; and mixtures thereof.  
   
   
       26 . The production assembly according to  claim 16 , wherein the degradable wrap is permeable enabling a production fluid to pass through the compressible foam element and the downhole sand control device.  
   
   
       27 . An apparatus for temporarily maintaining a compressible foam element in a compressed state against an outer surface of a downhole sand control device, comprising a degradable wrap securely fitted around the compressible foam element.  
   
   
       28 . The apparatus according to  claim 27 , wherein the degradable wrap is biodegradable and gradually degrades by thermal hydrolysis in the presence of an aqueous solution.  
   
   
       29 . The apparatus according to  claim 28 , wherein the biodegradable wrap is in the form of a string or tape, which is helically wound around the compressible foam element.  
   
   
       30 . The apparatus according to  claim 28 , wherein the biodegradable wrap is formed into a tubular sheath.  
   
   
       31 . The apparatus according to  claim 30 , wherein the biodegrable tubular sheath is formed of a woven cloth.  
   
   
       32 . The apparatus according to  claim 27 , wherein the degradable wrap comprises a degradable polymer selected from the group consisting of homopolymers, random, block, graft, and star- and hyper-branched aliphatic polyesters.  
   
   
       33 . The apparatus according to  claim 27 , wherein the degradable wrap comprises a degradable polymer selected from the group consisting of polysaccharides; chitins; chitosans; proteins; aliphatic polyesters; poly(lactides); poly(glycolides); poly(ε-caprolactones); poly(hydroxybutyrates); poly(anhydrides); aliphatic polycarbonates; poly(orthoesters); poly(amino acids); poly(ethylene oxides); and polyphosphazenes.  
   
   
       34 . The apparatus according to  claim 33 , wherein the degradable wrap comprises an aliphatic polyester having the general formula of repeating units shown below:  
     
       
         
         
             
             
         
       
     
     where n is an integer between 75 and 10,000 and R is selected from the group consisting of hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatoms, and mixtures thereof.  
   
   
       35 . The apparatus according to  claim 33 , wherein the degradable wrap further comprises a plasticizer.  
   
   
       36 . The apparatus according to  claim 35 , wherein the plasticizer comprises a derivative of oligomeric lactic acid, selected from the group defined by the formula:  
     
       
         
         
             
             
         
       
     
     where R is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R is saturated, where R′ is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R′ is saturated, where R and R′ cannot both be hydrogen, where q is an integer and 2≦q≦75; and mixtures thereof.  
   
   
       37 . The apparatus according to  claim 27 , wherein the degradable wrap is permeable enabling a production fluid to pass through the compressible foam and the downhole sand control device.