Method for removing alkaline sulfate scale
AssigneeMobil Oil Corporation
InventorsRichard L. Morris, James M. Paul
Life of this patent
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Abstract
Alkaline earth metal scales, especially barium sulfate scale deposits are removed from oilfield pipe and other tubular goods with a scale-removing composition comprising an aqueous alkaline solution having a pH of about 8 to about 14, a polyaminopolycarboxylic acid, preferably EDTA or DTPA and a catalyst or synergist comprising oxalate anion. When the scale-removing solution is contacted with a surface containing a scale deposit, substantially more scale is dissolved at a faster rate than previously possible.
Claims14
A method for removing alkaline earth sulfate scale comprising contacting the scale with an aqueous solution having a pH of about 8 to about 14 and comprising a chelating agent comprising a polyaminopolycarboxylic acid present in a concentration of from 0.1 M to 1.0 M or salt of such an acid, and a synergist which comprises oxalate anions present in a concentration of from 0.1 M to 1.0 M to dissolve the scale.
Dependencies are inferred from the claim text.