Aqueous solution and method for use thereof

Abstract

Oilfield treatment compositions contain water, hydrochloric acid at a concentration between 15 wt % and 45.7 wt % and a first and second fixing agent. The first fixing agent comprises urea, a urea derivative or both. The second fixing agent may be a mixture or amines and alcohols. These compositions provide corrosion inhibition when exposed to steel. The compositions may also contain an inhibitor aid.

What is claimed is: 
     
         1 . A composition, comprising:
 (i) water at a concentration lower than or equal to 20 wt %;   (ii) hydrochloric acid at a concentration between 15 wt % and 45.7 wt %;   (iii) a first fixing agent comprising urea, a urea derivative or both; and   (iv) a second fixing agent,   wherein the first fixing agent:hydrochloric acid molar ratio is between 0.4 and 3.0 inclusive.   
     
     
         2 . The composition of  claim 1 , wherein the urea derivative comprises 1,1-dimethylurea, 1,3-dimethylurea, 1,1-diethylurea, 1,3-diethylurea, 1,1-diallylurea, 1,3-diallylurea, 1,1-dipropylurea, 1,3-dipropylurea, 1,1-dibutylurea, 1,3-dibutylurea, 1,1,3,3-tetramethylurea, 1,1,3,3-tetraethylurea, 1,1,3,3-tetrapropylurea, 1,1,3,3-tetrabutylurea, ethyleneurea, propyleneurea, 1,3-dimethylpropyleneurea or 1,3-dimethylethyleneurea, or combinations thereof. 
     
     
         3 . The composition of  claim 1 , wherein the second fixing agent comprises a mixture of amines and alcohols. 
     
     
         4 . The composition of  claim 3 , wherein the concentration of the second fixing agent is between 0.1 wt % and 0.5 wt % inclusive. 
     
     
         5 . The composition of  claim 3 , further comprising an inhibitor aid comprising a mixture of phenyl ketones and quarternary amines. 
     
     
         6 . The composition of  claim 5 , wherein the concentration of the inhibitor aid is between 0.4 wt % and 0.8 wt % inclusive. 
     
     
         7 . The composition of  claim 1 , further comprising hydrofluoric acid at a concentration higher than or equal to 0.25 wt %. 
     
     
         8 .- 20 . (canceled)