Degradable Fluid Sealing Compositions Having an Adjustable Degradation Rate and Methods for Use Thereof

Abstract

When performing subterranean treatment operations, it can be desirable to temporarily divert or block fluid flow by forming a degradable fluid seal. Methods for forming a degradable fluid seal can comprise: providing a sealing composition comprising: a degradable polymer, and a water-soluble material comprising a first portion and a second portion of rigid particulates, each portion having a sealing time and a particulate size distribution associated therewith, the particulate size distributions of the first portion and the second portion differing from one another; determining an amount of the first portion relative to the second portion needed to produce a degradable fluid seal having a desired sealing time that is different than that of the sealing time of either the first portion or the second portion; introducing the sealing composition into a subterranean formation; and allowing the sealing composition to form a degradable fluid seal in the subterranean formation.

The invention claimed is: 
     
         1 . A method comprising:
 providing a sealing composition comprising:
 a degradable polymer, and 
 a water-soluble material comprising a first portion of rigid particulates and a second portion of rigid particulates, each portion of rigid particulates having a sealing time and a particulate size distribution associated therewith, the particulate size distributions of the first portion of rigid particulates and the second portion of rigid particulates differing from one another; 
   determining an amount of the first portion of rigid particulates relative to the second portion of rigid particulates in the sealing composition needed to produce a degradable fluid seal having a desired sealing time that is different than that of the sealing time of either the first portion of rigid particulates or the second portion of rigid particulates;   introducing the sealing composition into a subterranean formation; and   allowing the sealing composition to form a degradable fluid seal in the subterranean formation.   
     
     
         2 . The method of  claim 1 , wherein the water-soluble material comprises a water-soluble polymer. 
     
     
         3 . The method of  claim 2 , wherein the water-soluble polymer comprises at least one polymer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, acetyl cellulose, hydroxyethyl cellulose, shellac, chitosan, chitin, dextran, guar, xanthan, starch, a scleroglucan, a diutan, poly(vinyl pyrollidone), polyacrylamide, polyacrylic acid, poly(diallyldimethylammonium chloride), poly(ethylene glycol), poly(ethylene oxide), polylysine, polymethacrylamide, polymethacrylic acid, poly(vinylamine), any derivative thereof, any copolymer thereof, and any combination thereof. 
     
     
         4 . The method of  claim 1 , wherein the degradable polymer comprises particulates of a gelled degradable polymer. 
     
     
         5 . The method of  claim 3 , wherein the degradable polymer comprises at least one crosslinked polymer selected from the group consisting of a crosslinked polyacrylamide, a crosslinked polymethacrylamide, any hydrolyzed or partially hydrolyzed variant thereof, any derivative thereof, any copolymer thereof, and any combination thereof. 
     
     
         6 . The method of  claim 1 , wherein the degradable polymer comprises at least one crosslinked polymer selected from the group consisting of a crosslinked polyacrylamide, a crosslinked polymethacrylamide, any hydrolyzed or partially hydrolyzed variant thereof, any derivative thereof, any copolymer thereof, and any combination thereof. 
     
     
         7 . The method of  claim 6 , wherein the sealing composition is introduced into the subterranean formation in a treatment fluid having a basic pH. 
     
     
         8 . The method of  claim 1 , wherein at least a portion of the subterranean formation has a permeability of at least about 0.5 D. 
     
     
         9 . The method of  claim 1 , further comprising:
 performing a treatment operation in the subterranean formation while the degradable fluid seal is intact; and   allowing the degradable fluid seal to degrade.   
     
     
         10 . A method comprising:
 providing a sealing composition comprising:
 particulates of a gelled degradable polymer, and 
 a water-soluble material comprising rigid particulates having a sealing time and a particulate size distribution associated therewith, the particulate size distribution of the water-soluble material differing from that of a like unsized water-soluble material; 
   determining a particulate size distribution of the rigid particulates needed to produce a degradable fluid seal having a desired sealing time;   introducing the sealing composition into a subterranean formation;   forming a degradable fluid seal in the subterranean formation from the sealing composition;   performing a treatment operation in the subterranean formation while the degradable fluid seal is intact; and   allowing the degradable fluid seal to degrade.   
     
     
         11 . The method of  claim 10 , wherein, during or after degrading, the degradable fluid seal dissolves in a fluid present in the subterranean formation. 
     
     
         12 . The method of  claim 10 , wherein the water-soluble material comprises a first portion of rigid particulates and a second portion of rigid particulates, each portion having a sealing time and a particulate size distribution associated therewith, the particulate size distributions of the first portion of rigid particulates and the second portion of rigid particulates differing from one another. 
     
     
         13 . The method of  claim 12 , wherein a sealing time of the degradable fluid seal can be altered by changing an amount of the first portion of rigid particulates relative to the second portion of rigid particulates. 
     
     
         14 . The method of  claim 10 , wherein the water-soluble material comprises a water-soluble polymer. 
     
     
         15 . The method of  claim 14 , wherein the water-soluble polymer comprises at least one polymer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, acetyl cellulose, hydroxyethyl cellulose, shellac, chitosan, chitin, dextran, guar, xanthan, starch, a scleroglucan, a diutan, poly(vinyl pyrollidone), polyacrylamide, polyacrylic acid, poly(diallyldimethylammonium chloride), poly(ethylene glycol), poly(ethylene oxide), polylysine, polymethacrylamide, polymethacrylic acid, poly(vinylamine), any derivative thereof, any copolymer thereof, and any combination thereof. 
     
     
         16 . The method of  claim 10 , wherein the gelled degradable polymer comprises at least one crosslinked polymer selected from the group consisting of a crosslinked polyacrylamide, a crosslinked polymethacrylamide, any hydrolyzed or partially hydrolyzed variant thereof, any derivative thereof, any copolymer thereof, and any combination thereof. 
     
     
         17 . The method of  claim 16 , wherein the sealing composition is introduced into the subterranean formation in a treatment fluid having a basic pH. 
     
     
         18 . The method of  claim 10 , wherein at least a portion of the subterranean formation has a permeability of at least about 0.5 D. 
     
     
         19 . A method comprising:
 providing a plurality of gelled degradable polymer particulates;   providing a first portion of a water-soluble material and a second portion of a water-soluble material, each portion comprising rigid particulates and each portion having a sealing time and a particulate size distribution associated therewith, the particulate size distributions differing from one another;   mixing the first portion of the water-soluble material and the second portion of the water-soluble material with the plurality of gelled degradable polymer particulates, thereby forming a sealing composition;   determining an amount of the first portion of the water-soluble material relative to the second portion of the water-soluble material in the sealing composition needed to produce a degradable fluid seal having a desired sealing time that is different than that of the sealing time of either the first portion of the water-soluble material or the second portion of the water-soluble material; and   introducing the sealing composition into a subterranean formation to form a degradable fluid seal therein.   
     
     
         20 . The method of  claim 19 , further comprising:
 choosing the particulate size distributions of the first portion of the water-soluble material and the second portion of the water-soluble material needed to produce a degradable fluid seal having a desired sealing time.   
     
     
         21 . The method of  claim 19 , wherein the water-soluble material comprises a water-soluble polymer. 
     
     
         22 . The method of  claim 21 , wherein the water-soluble polymer comprises at least one polymer selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, acetyl cellulose, hydroxyethyl cellulose, shellac, chitosan, chitin, dextran, guar, xanthan, starch, a scleroglucan, a diutan, poly(vinyl pyrollidone), polyacrylamide, polyacrylic acid, poly(diallyldimethylammonium chloride), poly(ethylene glycol), poly(ethylene oxide), polylysine, polymethacrylamide, polymethacrylic acid, poly(vinylamine), any derivative thereof, any copolymer thereof, and any combination thereof. 
     
     
         23 . The method of  claim 19 , wherein the gelled degradable polymer comprises at least one crosslinked polymer selected from the group consisting of a crosslinked polyacrylamide, a crosslinked polymethacrylamide, any hydrolyzed or partially hydrolyzed variant thereof, any derivative thereof, any copolymer thereof, and any combination thereof.