Evaluation of the effectiveness of mixing hydrochloric acid and organic acid as stimulation fluids in a tight gas carbonate reservoir

Matrix acidizing is a widely used technique in carbonate formations to improve production and injection rates by restoring or improving permeability. This study evaluates the stimulation efficacy of organic and inorganic acid combinations in the Sarajeh carbonate formation, with a focus on improving permeability within this potential tight gas formation. Through solubility and continuous flow tests, a mixture of HCl 7.5% + HAc 2.5% was found to significantly outperform the traditional HCl 15% solution. The HCl 7.5% + HAc 2.5% mixture had a solubility rate of 59.27% and improved permeability by 4.4 times compared to HCl 15%, indicating a higher dissolving capacity. The results of continuous flow tests showed that the mixed acid had the best pore volume to breakthrough (PVBt) value of 2.574 at a controlled injection rate of 2 cc/min. This study demonstrates the superior performance of a lower concentration HCl‐HAc acid formulation in matrix acidizing carbonate formations and confirms its potential as a more effective alternative to high concentration HCl treatments for the Sarajeh reservoir.