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• The reason for the poor effect of acid fracturing with retarded acid in dolomite reservoir was found. • The correlation between the acid-rock reaction control mode and etching morphology was analyzed. • The effects of different factors on the conductivity of fractures were studied. • Two uneven acid injection approaches were discussed. Retarded acids are often used for acid fracturing in carbonate reservoirs to reduce acid leakoff. Compared with limestone reservoirs, dolomite reservoirs are seen with lower fracture conductivity using retarded acid. This study focuses on the acid etching morphology of fracture, and investigates influential factors and improvement methods of fracture conductivity. Our analysis shows the etching morphology has no direct dependency upon the controlling regime of acid-rock reaction. It is determined by reaction rates. Low conductivity is caused by the slow reaction between dolomite and retarded acid, and difficulties in creating irregular etched grooves on fracture surfaces. A small amount of dolomite in reservoirs does not impact conductivity, and yet dolomitic contents over 80% will lead to tremendous reduction of conductivity. It is feasible to form the irregular etching morphology by reducing the flow rate and the thickening agent concentration while alternately injecting two types of acid solutions into reservoirs. [ABSTRACT FROM AUTHOR]