Method for dissolving oilfield scale
AssigneesM-1 Production Chemicals UK Limited, Oilfield Mineral Solutions Limited
InventorRichard Keatch
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Abstract
A method of removing metal scale from surfaces that includes contacting the surfaces with a first aqueous solution of a chelating agent, allowing the chelating agent to dissolve the metal scale, acidifying the solution to form a precipitant of the chelating agent and a precipitant of the metal from the metal scale, isolating the precipitant of the chelating agent and the precipitant of the metal from the first solution, selectively dissolving the precipitated chelating agent in a second aqueous solution, and removing the precipitated metal from the second solution is disclosed.
Claims21
A method of removing metal scale from surfaces, comprising:
- contacting the surfaces with a first aqueous solution comprising:
- a chelating agent;
- allowing the chelating agent to dissolve the metal scale from the surfaces into the first aqueous solution;
- acidifying the first aqueous solution to form a precipitant of the chelating agent and a precipitant of the metal from the metal scale in the first aqueous solution, wherein both the precipitant of the chelating agent and the precipitant of the metal are present together in the first aqueous solution;
- isolating the precipitant of the chelating agent and the precipitant of the metal from the first aqueous solution and introducing the precipitant of the chelating agent and the precipitant of the metal into a second aqueous solution;
- selectively dissolving the precipitant of the chelating agent in the second aqueous solution;
- and
- removing the precipitant of the metal from the second aqueous solution.
A method of removing scale from surfaces, comprising:
- contacting the surfaces with a first aqueous solution comprising:
- EDTA;
- and
- potassium carbonate;
- allowing the EDTA to dissolve the scale from the surfaces into the first aqueous solution, wherein the scale comprise at least one of barium sulfate, strontium sulfate, and radium sulfate;
- acidifying the first aqueous solution to form a precipitant of EDTA and precipitant of an insoluble salt of at least one of barium, strontium, and radium in the first aqueous solution, wherein both the precipitant of EDTA and the precipitant of the insoluble salt are present together in the first aqueous solution;
- isolating the precipitant of EDTA and the precipitant of the insoluble salt of the at least one of barium, strontium, and radium from the first aqueous solution and introducing the precipitant of EDTA and the precipitant of the insoluble salt into a second aqueous solution;
- selectively dissolving the precipitant of EDTA in the second aqueous solution;
- and
- removing the precipitant of the insoluble salt of at least one of barium, strontium, and radium from the second aqueous solution.
Dependencies are inferred from the claim text.