Matrix acidification is one of the important measures for the stimulation of carbonate reservoirs. The studies on its formation regularity and influencing factors of acid wormhole are the basic theories of carbonate matrix acidification. An orthogonal experimental scheme considering three factors of acid injection rate

acid concentration and reaction temperature was designed. Acid displacement experiments were carried out on the cores taken from a carbonate reservoir in oilfield A. The influence of the factors on wormhole shape was studied by fractal dimension and multi-fractal spectrum width used as the target parameters. The optimization goal is to try to ensure the minimum width of multifractal spectrum while obtaining the maximum fractal dimension. Th

e results showed that in the range of factor values

the optimal combination of experimental parameters for wormhole shape was when the acid concentration was 20 %

the temperature was 50~70 °C

and the acid injection rate was 2 cm

3

/min. The factors affecting the fractal dimension and multi-fractal spectrum width were in a descending order as: acid injection rate

acid concentration and reaction temperature. Therefore

the optimization of the acid injection displacement should be emphasized in the design of the construction parameters of carbonate matrix acidification.