Effect of Chelating Agents on Tight Sandstone Formation Mineralogy During Sandstone Acidizing

Abstract

Dissolution of the wellbore damage is the main target of sandstone acidizing. The presence of minerals like clays, feldspar, zeolites, and alumino-silicates makes acidizing a challenging task because they may form undesired products (precipitates) when reacted with mud acid. Secondary and tertiary reactions are responsible for the formation of these products. To avoid the formation of precipitates, which are formed due to the reaction of conventional acids with minerals, chelating agents were utilized in this research paper. The chelating agents provide the advantage of deep penetration and slow reaction rate. The chelating agents HEDTA (hydroxyethylethylenediaminetriacetic acid), GLDA (tetrasodium glutamate diacetate), and EDTA (ethylethylenediaminetriacetic acid) were allowed to react with Colton sandstone formation under 1,000 psi confining pressure and 180°F temperature. The reacted core samples were tested for different analyses to analyze the effect of chelates on the core sample properties. The analyses performed are elemental analysis, mineral analysis, grain-size analysis, and porosity, particle, and density analysis. In elemental analysis, due to the tight nature of the Colton sandstone, the chelates were not that effective. From mineral analysis, HEDTA proved to be effective in the dissolution of quartz, ankerite, orthoclase, and calcite compared to GLDA and EDTA. According to a porosity analysis investigation, HEDTA produced the most additional pore spaces when reacted with the Colton sandstone formation.