Gas hydrate inhibitors and methods for making and using same

Abstract

Phosphate brine compositions reduce hydrate formation in flowlines under conditions conducive for hydrate formation in the absence of the phosphate, where the phosphate brines include a compatible anti-corrosion system and may include nitrate brines.

We claim: 
     
         1 . A method for inhibiting gas hydrate formation in downhole fluids comprising:
 using a downhole fluid including:
 a base fluid comprising a phosphate brine, and 
 an inhibiting amount of a corrosion system including:
 at least one compatible anti-corrosion and/or neutralization additive is selected from the group consisting of mono carboxylic acids, dicarboxylic acids, poly carboxylic acids, hydrochloric acid (HC1), hydrobromic acid (HBr), sulfuric acid, sulfonic acids, sulfinyl acids, phosphoric acid, polyphosphoric acid, and mixtures or combinations thereof, 
 
   where the base fluid reduces or inhibits hydrocarbon gas hydrate formation under conditions conducive to hydrocarbon gas hydrate formation in the downhole fluid, and   where the additives reduce or prevent corrosion by the base fluid.   
     
     
         2 . The method of  claim 1 , wherein the downhole fluid comprises a drilling fluid, a completion fluid, or a production fluid. 
     
     
         3 . The method of  claim 1 , wherein the downhole fluid further includes:
 an effective amount of a foaming system and a gas to form a foamed downhole fluid having desired foam properties.   
     
     
         4 . The method of  claim 3 , wherein the foamed downhole fluid comprises a foamed drilling fluid, a foamed completion fluid or a foamed production fluid. 
     
     
         5 . The method of  claim 1 , wherein:
 the phosphate brines for use in the present invention include, without limitation, phosphoric acid brines, polyphosphoric acid brines, alkali metal phosphate brines, alkaline earth metal phosphate brines, transition metal phosphate brines, and mixtures or combinations thereof.   
     
     
         6 . The method of  claim 5 , wherein:
 the alkali metal phosphate brines include mono lithium hydrogen phosphate brines, mono sodium hydrogen phosphate brines, mono potassium hydrogen phosphate brines, mono rubidium hydrogen phosphate brines, mono cesium hydrogen phosphate brines, di-lithium hydrogen phosphate brines, di-hydrogen phosphate brines, di-potassium hydrogen phosphate brines, di-rubidium hydrogen phosphate brines, di-cesium hydrogen phosphate brines, and mixture or combinations thereof,   the alkaline earth metal phosphate brines include magnesium phosphate brines, calcium hydrogen phosphate brines, and mixture or combinations thereof, and   the transition metal phosphate brines include zinc phosphate brines, and mixture or combinations thereof.   
     
     
         7 . The method of  claim 1 , wherein the base fluid further includes:
 a nitrate brine.   
     
     
         8 . The method of  claim 7 , wherein the nitrate brines are selected from the group consisting of alkali metal nitrate brines, alkaline earth metal nitrate brines, transition metal nitrate brines, and mixtures or combinations thereof. 
     
     
         9 . The method of  claim 8 , wherein:
 the alkali metal nitrate brines are selected from the group consisting of lithium nitrate brines, sodium nitrate brines, potassium nitrate brines, rubidium nitrate brines, cesium nitrate brines, and mixture or combinations thereof,   the alkaline earth metal nitrate brines are selected from the group consisting of magnesium nitrate brines, calcium nitrate brines, and mixture or combinations thereof, and   the transition metal nitrate brines are zinc nitrate brines.   
     
     
         10 . The method of  claim 1 , wherein:
 the mono-, di- and polycarboxylic acids are selected from the group consisting of saturated carboxy acids having from 1 to about 20 carbon atoms, unsaturated carboxy acids having from about 2 to about 20 carbon atoms, aromatic acids having from about 5 to about 30 carbon atoms, saturated dicarboxy acids having from 1 to about 20 carbon atoms, unsaturated dicarboxy acids having from about 2 to about 20 carbon atoms, aromatic diacids having from about 5 to about 30 carbon atoms, saturated polycarboxy acids having from 1 to about 20 carbon atoms, unsaturated polycarboxy acids having from about 2 to about 20 carbon atoms, aromatic polyacids having from about 5 to about 30 carbon atoms, or mixtures and combinations thereof, and   the sulfonic acids include, without limitation, alkyl sulfonic acids, alkenyl sulfonic acids, aryl sulfonic acids, where the alkyl groups include 1 to about 20 carbon atoms, the alkenyl groups include 2 to about 20 carbon atoms and the aryl groups include 5 to about 30 carbon atoms.   
     
     
         11 . The method of  claim 1 , wherein the corrosion system further includes:
 a quaternary salt selected from the group consisting of quaternary ammonium salts (R 1 R 2 R 3 R 4 N + A − ), quaternary phosphonium salts (R 1 R 2 R 3 R 4 P + A − ), amines (R 1 R 2 R 3 N), phosphines (R 1 R 2 R 3 P), and mixtures or combinations thereof, where the R 1 , R 2 , R 3  and R 4  are the same or different and are carbyl groups having between 1 and about 20 carbon atoms selected from the group consisting of saturated, unsaturated, cyclic, acyclic, aromatic, or mixed carbyl groups and sufficient hydrogen atoms to satisfy the valence, where one or more carbon atoms may be replaced by a hetero atom or group selected from oxygen, sulfur, amido, boron, or mixtures thereof, and one or more of the hydrogen atoms can be replace by halogens, alkoxides, or mixtures thereof, where A −  is a counterion selected from the group consisting of hydroxide ion (OH), a halogen ion including F − , Cl − , Br−, and I−, a sulfate ion (SO 4   2− ), a nitrate ion (NO 3   − ), or mixtures thereof.   
     
     
         12 . A downhole fluid composition:
 a base fluid comprising a phosphate brine, and   an inhibiting amount of a corrosion system including:
 at least one compatible anti-corrosion and/or neutralization additive is selected from the group consisting of mono carboxylic acids, dicarboxylic acids, poly carboxylic acids, hydrochloric acid (HC1), hydrobromic acid (HBr), sulfuric acid, sulfonic acids, sulfinyl acids, phosphoric acid, polyphosphoric acid, and mixtures or combinations thereof, 
   where the base fluid reduces or inhibits hydrocarbon gas hydrate formation under conditions conducive to hydrocarbon gas hydrate formation in the completion fluid, and   where the additives reduce or prevent corrosion by the base fluid.   
     
     
         13 . The composition of  claim 12 , wherein the downhole fluid comprises a drilling fluid, a completion fluid, or a production fluid. 
     
     
         14 . The composition of  claim 12 , wherein the downhole fluid further include:
 an effective amount of a foaming system and a gas to form a foamed downhole fluid having desired foam properties.   
     
     
         15 . The composition of  claim 14 , where the foamed downhole fluid comprises a foamed drilling fluid, a foamed completion fluid or a foamed production fluid. 
     
     
         16 . The composition of  claim 12 , wherein:
 the phosphate brines for use in the present invention include, without limitation, phosphoric acid brines, polyphosphoric acid brines, alkali metal phosphate brines, alkaline earth metal phosphate brines, transition metal phosphate brines, and mixtures or combinations thereof.   
     
     
         17 . The composition of  claim 16 , wherein:
 the alkali metal phosphate brines include mono lithium hydrogen phosphate brines, mono sodium hydrogen phosphate brines, mono potassium hydrogen phosphate brines, mono rubidium hydrogen phosphate brines, mono cesium hydrogen phosphate brines, di-lithium hydrogen phosphate brines, di-hydrogen phosphate brines, di-potassium hydrogen phosphate brines, di-rubidium hydrogen phosphate brines, di-cesium hydrogen phosphate brines, and mixture or combinations thereof,   the alkaline earth metal phosphate brines include magnesium phosphate brines, calcium hydrogen phosphate brines, and mixture or combinations thereof, and   the transition metal phosphate brines include zinc phosphate brines, and mixture or combinations thereof.   
     
     
         18 . The composition of  claim 12 , wherein the base fluid further includes:
 a nitrate brine.   
     
     
         19 . The composition of  claim 18 , wherein the nitrate brines are selected from the group consisting of alkali metal nitrate brines, alkaline earth metal nitrate brines, transition metal nitrate brines, and mixtures or combinations thereof. 
     
     
         20 . The composition of  claim 19 , wherein:
 the alkali metal nitrate brines are selected from the group consisting of lithium nitrate brines, sodium nitrate brines, potassium nitrate brines, rubidium nitrate brines, cesium nitrate brines, and mixture or combinations thereof,   the alkaline earth metal nitrate brines are selected from the group consisting of magnesium nitrate brines, calcium nitrate brines, and mixture or combinations thereof, and   the transition metal nitrate brines are zinc nitrate brines.   
     
     
         21 . The composition of  claim 12 , wherein:
 the mono-, di- and polycarboxylic acids are selected from the group consisting of saturated carboxy acids having from 1 to about 20 carbon atoms, unsaturated carboxy acids having from about 2 to about 20 carbon atoms, aromatic acids having from about 5 to about 30 carbon atoms, saturated dicarboxy acids having from 1 to about 20 carbon atoms, unsaturated dicarboxy acids having from about 2 to about 20 carbon atoms, aromatic diacids having from about 5 to about 30 carbon atoms, saturated polycarboxy acids having from 1 to about 20 carbon atoms, unsaturated polycarboxy acids having from about 2 to about 20 carbon atoms, aromatic polyacids having from about 5 to about 30 carbon atoms, or mixtures and combinations thereof, and   the sulfonic acids include, without limitation, alkyl sulfonic acids, alkenyl sulfonic acids, aryl sulfonic acids, where the alkyl groups include 1 to about 20 carbon atoms, the alkenyl groups include 2 to about 20 carbon atoms and the aryl groups include 5 to about 30 carbon atoms.   
     
     
         22 . The composition of  claim 12 , wherein the corrosion system further includes:
 a quaternary salt selected from the group consisting of quaternary ammonium salts (R 1 R 2 R 3 R 4 N + A − ), quaternary phosphonium salts (R 1 R 2 R 3 R 4 P + A − ), amines (R 1 R 2 R 3 N), phosphines (R 1 R 2 R 3 P), and mixtures or combinations thereof, where the R 1 , R 2 , R 3  and R 4  are the same or different and are carbyl groups having between 1 and about 20 carbon atoms selected from the group consisting of saturated, unsaturated, cyclic, acyclic, aromatic, or mixed carbyl groups and sufficient hydrogen atoms to satisfy the valence, where one or more carbon atoms may be replaced by a hetero atom or group selected from oxygen, sulfur, amido, boron, or mixtures thereof, and one or more of the hydrogen atoms can be replace by halogens, alkoxides, or mixtures thereof, where A −  is a counterion selected from the group consisting of hydroxide ion (OH − ), a halogen ion including F − , Cl − , Br−, and I−, a sulfate ion (SO 4   2− ), a nitrate ion (NO 3   − ), or mixtures thereof.