Mineral Analysis of Dolomite Formation During Carbonate Acidizing Using Chelating Agents

DOI: 10.14800/IOGR.1362

Abstract

During carbonate acidizing, the reaction between hydrochloric acid (HCl) and carbonate minerals is particularly rapid, especially in high-temperature wellbore environments. Due to the swift reaction kinetics and the rapid consumption of acid, deep penetration is often limited, resulting in the formation of small wormholes and localized dissolution, which minimizes skin damage. To address these challenges, chelating agents have been introduced as an alternative for reacting with dolomite formations. Chelating agents, being slower-reacting acids, have demonstrated effectiveness in high-temperature environments. In this study, three chelating agents—HEDTA (Hydroxyethylenediaminetetraacetic acid), GLDA (L-glutamic acid diacetic acid), and EDTA (Ethylenediaminetetraacetic acid)—were employed to interact with Guelph dolomite core samples under high-pressure (1000 psi) and high-temperature (180°F) conditions. The reacted dolomite samples were subsequently analyzed for changes in various properties, including mineralogy, grain size distribution, porosity, and morphology. Mineralogical and grain size distribution analyses revealed that GLDA and HEDTA were effective in dissolving calcite, while EDTA demonstrated a higher effectiveness in dissolving ankerite. Additionally, mineral locking analysis indicated that GLDA and HEDTA successfully disrupted the bond between quartz and calcite, which may contribute to an increase in reservoir permeability.