Mineral analysis of sandstone formation using chelating agents during sandstone matrix acidizing

Abstract

For many years, the most common acid practice for sandstone acidizing is based on mud acid and dolomite formations using hydrochloric acid. During various stages of sandstone acidizing, different acids react with different minerals, and interactions of minerals with acids are an origin for precipitation reactions, which can be possibly deleterious as they may reduce reservoir permeability. During this research, the effects of chelates on pore size distribution, mineralogy, and grain size distribution have been investigated. Various chelates (GLDA, HEDTA, EDTA) were examined to react with different Berea Sandstone samples at a temperature of 180 °F and under 1000 psi confining pressure. Experimental techniques and analysis like Tescan Integrated Mineral Analysis (TIMA), were implemented in this research to understand the effect of chelates on Berea Sandstone. These results are related to elemental mass, element deportment, mineral mass, mineral locking, grain size distribution, and particle size distribution of the core samples reacted with different chelating agents. It has been found that all the chelating agents are effective in increasing the porosity and dissolving the cations from the Berea sandstone core sample. HEDTA proved to be more effective in dissolving quartz as compared to other chelates. GLDA proved to be more effective in the dissolution of rutile and zircon minerals. The significance of this research is the application of environment-friendly chelating agents to sandstone formation. Moreover, the detailed mineral analysis revealed that the most number of particles were dissolved by HEDTA.