Abstract: Acid fracturing as an important stimulation technology for carbonate reservoir is closely related with reaction process of acidrock reaction process in effectiveness. The previous acid-rock reaction models have failed to describe fractal feature of rock particle surface and 3D corrosion of acidic liquid on the grain, so there are obvious differences compared with such a real reaction process. This paper conducts regular characterization of the area and volume of rough rock particles by method of fractal geometry, develops the fractal mathematic model of 3D acid corrosion of rough carbonate rock particles on the basis of chemical reaction kinetics and mass transfer theory, and analyzes the variation trends of total corrosion time and corrosion rate of carbonate rocks. The study shows that the effect of fractal dimension of carbonate rock particle on the total corrosion time is remarkable, and the larger the fractal dimension, the longer the total corrosion time; moreover, such a time is not increasing or decreasing monotonously with the increases of rock equivalent radius and main concentration of hydrogen ion content. For a certain relative reaction time, the larger the fractal dimension, the higher the particle corrosion rate.

Key words: fractal, mathematic model, carbonate rock, acid fracturing