Additive for preserving the fluidity of fluids containing gas hydrates

Abstract

Anti-agglomerants for gas hydrates, comprising alkoxylated and/or acylated non-quaternary nitrogen-containing compounds, method for inhibiting the agglomeration of gas hydrates in a conduit, and compositions comprising the gas hydrate anti-agglomerant, a corrosion inhibitor and/or a paraffin deposition inhibitor.

1 . An anti-agglomerant for gas hydrates, which comprises at least one surface-active non-quaternary nitrogen-containing compound chosen from the group of compounds having the formulae IA and II: 
       
         
           
           
               
               
           
         
         wherein R is a C 6 -C 24  hydrocarbyl group; m is 2 or 3; a=0-4; b is at least 1 at each position; Σb on average is 2-12; c is 0 or 1; d on average is 0-5; each A is independently selected from H, —C(═O)CH 3 , 
         —C(═O)CH 2 CH 3 , C1-C3 alkyl groups, —[CH 2 CH(X)O], H, and 
         —[CH 2 CH(X)O], —C(═O)CH 3 , wherein X is —CH 3  or —CH 2 CH 3 , e is 1-3, and the sum of all e in the molecule is at most 6 on average; provided that at least one of groups A is selected from the group consisting of 
         —[CH 2 CH(X)O], H, —[CH 2 CH(X)O], —C(═O)CH 3 , —C(═O)CH 3 , and 
         —C(═O)CH 2 CH 3 ; 
       
       
         
           
           
               
               
           
         
         wherein R′C(═O)— is an acyl group with 6-24 carbon atoms; o=0-3, p=0-3, Σ(o+p) on average is 0-6; m is 2 or 3, and each A is independently selected from H, —[CH 2 CH(X)O], H, —[CH 2 CH(X)O], —C(═O)CH 3 , 
         —C(═O)CH 3 , —C(═O)CH 2 CH 3  and C1-C3 alkyl groups; provided that at least one of groups A is —[CH 2 CH(X)O], H, —[CH 2 CH(X)O], —C(═O)CH 3 , 
         —C(═O)CH 3  or —C(═O)CH 2 CH 3 , wherein X, e and Σe have the same meaning as for IA; 
         or their salts; or any combination thereof. 
       
     
     
         2 . Anti-agglomerant according to  claim 1  selected from the group of compounds having the formulae IIA and IIB, wherein
 IIA has the formula 
 
       
         
           
           
               
               
           
         
         wherein n is at least 1 at each position and Σn on average is 2-4, m is 2 or 3, R(C═O)— and A are as defined for II except that X is —CH 3 , provided that at least one of A is —[CH 2 CH(CH 3 )O], H, 
         —[CH 2 CH(CH 3 )O], —C(═O)CH 3  or —C(═O)CH 3 , wherein e and Σe are as defined for II; 
         IIB has the formula 
       
       
         
           
           
               
               
           
         
         wherein m is 2 or 3; R(C═O)— and A are as defined for II except that X is —CH 3 , provided that at least one of A is —[CH 2 CH(CH 3 )O], H, 
         —[CH 2 CH(CH 3 )O], —C(═O)CH 3  or —C(═O)CH 3 , wherein e and Σe are as defined for II; 
         their salts; or any combination thereof. 
       
     
     
         3 . Anti-agglomerant according to  claim 1 , comprising the compound of formula IA, wherein R is a C 8 -C 18  hydrocarbyl group; a is 0 or 1; m is 3; c is 0; the sum of b on average is 2-6; and all A are either
 —[CH 2 CH(CH 3 )O], H, wherein the sum of all e in the molecule is 2 or 3, or —C(═O)CH 3 .   
     
     
         4 . Anti-agglomerant according to  claim 3  wherein Σb on average is 2-3. 
     
     
         5 . A method for inhibiting the agglomeration of gas hydrates in a conduit, where the conduit contains a flowing mixture comprising hydrocarbons with 1-4 carbon atoms and water and where hydrates are formed from the hydrocarbons and water, the method comprising the steps:
 a) adding to the mixture an anti-agglomerant as defined in any of the previous claims in an amount that is effective to inhibit the agglomeration of hydrates at the prevailing temperature and pressure in the conduits   b) flowing the mixture containing the anti-agglomerant through the conduit.   
     
     
         6 . The method according to  claim 5  wherein the anti-agglomerant is added to the hydrocarbon/water mixture in an amount of 0.05-10%, based on the water content of the hydrocarbon/water mixture. 
     
     
         7 . The method according to  claim 5  wherein a corrosion inhibitor and/or a paraffin deposition inhibitor are added to the hydrocarbon/water mixture. 
     
     
         8 . A composition containing a) 1 part by weight of the gas hydrate anti-agglomerant as defined in  claim 1  and
 b) 0.0001-0.1 parts by weight of a corrosion inhibitor and/or a paraffin deposition inhibitor.