Relevance. The trend of an annual increase in the share of fields introduced into industrial development and confined to carbonate reservoirs. Predetermines the prospects for the development of inflow stimulation methods. The article deals with issues related to increasing the efficiency of hydrochloric acid treatments of carbonate reservoirs. Aim. Determination of technological solutions to increase the efficiency of hydrochloric acid treatments on carbonate reservoirs. Methods. Experimental research, statistical methods. Results and conclusions. The paper introduces the analysis of acid compositions used for hydrochloric acid treatments and the results of laboratory studies of hydrochloric acid compositions on core samples in the Eastern Siberia. The authors have determined the compatibility of formation fluids and acid compositions as well as the rate of core dissolution for selected compositions. The authors carried out the experiments on measuring the filtration-capacitive properties of core samples. The effectiveness of using urea as a hydrochloric acid modifier for selective hydrochloric acid treatments of carbonate reservoirs was confirmed in laboratory conditions. The authors obtained the changes in the rate of hydrochloric acid with dolomite from urea residues. They assessed the expected effect from the use of urea in hydrochloric acid treatments of carbonate reservoirs and the predicted values of the increase in oil production after hydrochloric acid treatments with urea. It was shown that using an acid composition with urea increases the efficiency of oil production by 26% compared to the application of a base solution of 24% HCl during in hydrochloric acid treatments. The paper introduces the analysis of the competitive advantages of urea in comparison with analogues on the Russian market. This showed that this reagent is widely available on the Russian market and its cost is lower than that of the reagents presented when testing acid compositions.