Oilfield Scale Removal by Chelating Agents: An Aminopolycarboxylic Acids Review

Abstract This literature review summarizes the theory and application of chelating agents in scale removal. The objective of this work is to give the reader a better understanding of scale removal methods by chelating agents in oil field applications. This paper reviews results that were obtained through various laboratory tests, which aid in understanding chelating agent interactions with formation rock and formation fluids. Results were obtained through a variety of tests including compatibility, dissolution, Inductively Coupled Plasma (ICP), Environmental Scanning Electron Microscope (ESEM) and X-Ray Diffraction (XRD). At high temperatures, conventional acids such as hydrochloric acid (HCl) show severe corrosion, lack of penetration and sludging characteristics. Several organic acids were proposed to solve these issues. However, even organic acids result in solubility and incompatibility issues. Based on these shortcomings, chelating agents are often used and show good dissolving power, low corrosion, low sludging tendencies, excellent iron control, and some are highly degradable and environmentally friendly. In addition, chelating agents are commonly used to dissolve most oil field scales that are both insoluble in HCl and detrimental to production. This work summarizes the applications of chelating agents in the stimulation sector, including the latest developments and field applications of chelating agents. Readers can easily expand on this paper to further explore the wide range of applications chelating agents can offer the oil and gas industry.