Polyhydrogen Acid (MF) is a multi-stage acid system developed to meet the requirements of deep acidizing operations. It is a retardant acid with multi-level ionization capability. Each MF molecule contains multiple hydrogen ions (H⁺), but the reactivity of these H⁺ ions varies according to their positions, with each ionization stage having roughly the same activity.
During application, under formation conditions, the most active first-stage H⁺ ions are released first to provide acidity, followed by subsequent ionization stages. This ensures a gradual release of H⁺ ions and a balanced hydrogen-ion concentration throughout the entire reaction process, effectively reducing the damage caused by strong acids in the near-wellbore zone. As a result, the acid system gains enhanced deep-penetrating stimulation capability. In addition, MF has strong chelating ability, anti-emulsification properties, and acid-residue resistance. It also exhibits strong adsorption on clays and rocks, making it an excellent retarder for HF acid systems.