Study of Barium Sulfate Scale Dissolution into Ethylenediaminetetraacetic acid (EDTA)

Abstract

Barium sulfate (barite) scale deposition may cause the problem in surface and subsurface production equipment resulting in reduced production, decrease in pressure, and premature failure of down holes equipment. One of the barite scale management is by using dissolver. There are many chelating agents that can be used to dissolve this scale including ethylenediaminetetraacetic acid (EDTA). In this work, EDTA is used to dissolve the laboratory-reproduced barium sulfate scale. Barite scale was reproduced in the laboratory by mixing barium chloride (BaCl2) solution and sodium sulfate (Na2SO4) solution at 25°C. The sensitivity analysis was performed to determine the optimum parameters/conditions in which EDTA dissolution is optimum through Inductively Coupled Plasma Optical Emission Spectrometry (ICP-EOS) analysis and characterization study using Field Emission Scanning Electron Microscope (FESEM). This includes the effect of agitation, temperature, pH, catalyst used, and the presence of oxalate ion. These laboratory tests showed that the solubility of barite increased as it was agitated; at high pH of 11 to 13; and at elevated temperature of 95°C. Potassium chloride (KCl) at high elevated temperature was used as synergy/activator to improve the dissolution of barium sulfate with EDTA. As a conclusion, this project sets a framework to identify the best EDTA formulation and estimate its dissolution profile to ensure a more informed treatment design for barite scale removal.