Chelating Agents in Productivity Enhancement: A Review

摘要

This literature review summarizes the theory and application of chelating agents in acidizing both carbonate and sandstone formations, and in hydraulic fracturing. The objective of this work is to explain the key role that chelating agents play in stimulation. This paper reviews results that were obtained through various laboratory tests, which aid in understanding chelating agent interactions with formation rock and fluids. Results were obtained through the following tests: coreflooding, corrosion tests, compatibility, Inductively Coupled Plasma (ICP), Environmental Scanning Electron Microscope (ESEM) and X-Ray Diffraction (XRD). At high temperatures, conventional acids such as HCl show severe corrosion, lack of penetration and sludging characteristics. Several organic acids were proposed in the reviewed literature 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 to acidizing, chelating agents allow for the application of saline water fracturing because of their water-softening properties. They also contribute to high-temperature water fracturing through delayed chelation of both the crosslinker and breaker. This work summarizes the applications of chelating agents in the stimulation sector. Over 100 papers were reviewed, including the latest developments and field applications of this technology. Readers can easily expand on this paper to further explore the wide range of applications chelating agents can offer the oil and gas industry.