An Efficient Single Step Approach for Barium Sulfate (BaSO₄) Scale Removal at High Temperature

The barite scale (barium sulfate) is considered one of the most common scales in oil and gas wells. Barite scale removal is crucial for flow assurance but it still represents a challenge to the oil and gas industry because of its low solubility in water and mineral acids such as HCl. Despite the huge amounts of chelating agents required to remove the barite scale, the solubility of barite (BaSO₄) in these chelates is very limited. In this experimental work, a new formulation to remove the barite scale is presented with a small volume of chelating agent used and a converting agent as the main feature of the dissolver. Dissolution of BaSO₄ was conducted using tetrapotassium ethylene-diamine-tetra-acetic acid (K4-EDTA) chelating agent and then obtaining the dissolution rate at 200°F to mimic the wellbore condition. The concentration of the K4-EDTA was selected based on the optimum dissolution rate of BaSO₄ at 24 h of soaking time. The variation of pH was investigated using potassium base KOH at two different pH values (10.5 and 13). Converting agent concentrations were obtained based on the high solubility of the scale to the total amount of solids. As the result of the study, it was revealed that a 15 wt% concentration of potassium base EDTA with 10 wt% K₂CO₃ as a converting agent at high pH was highly effective in dissolving up to 100% of 3 wt% BaSO₄ in less than 6 h at temperatures of 200°F and 300°F. This new formulation has proven to be a reliable and efficient solution for removing BaSO₄ from wellbores and surface equipment.