Calcium Sulfate Scale Dissolution Efficiency by Various Chemicals Additives

Abstract

Calcium sulfate scale is one of the challenges that face production stability in the oilfield industry as it is one of the most challenging scales to manage. Sulfate-scales are very hard to dissolve because of their low solubility-product. This work studies the dissolution capacity of different chemical additives and recipes on calcium sulfate scales. In this work, the maximum dissolution capacity (gram of scale/mole of chelating agent) of various chemical additives and recipes will be studied to evaluate the efficiency in the dissolution of Calcium Sulfate scales. Several experiments were conducted at multiple doses, pH, and in-presence of a catalyst. Potassium Carbonate was used as a catalyst in the dissolution of Calcium Sulfate scales. The performance of each additive was studied in a catalyzed and non-catalyzed pathway and with various. A Series of experiments conducted showed that parameters such as the additive-dose, pH, and a catalyst affect the dissolution efficiency. The dissolution performance efficiency of each additive (Lactic Acid, Citric Acid, L-Glutamic Acid-N, N-diacetic Acid (GLDA), and Gluconic Acid) was compared to the additive performance efficiency under a catalyzed pathway in a formulated recipe. The outcome of this work will contribute to the economic value added by finding the most efficient and cheap recipe to remove Calcium Sulfate scales from the wellbore.