This paper considers the dissolution of a carbonate rock in a rectangular HxL 2D domain using a two-scale mathematical model. The impact of the aspect ratio (F=H/L) on the dissolution at the "core" and "wellbore" scales was studied. As the scale of the domain increase, the wormhole structure changes from a straighter and wider to a thinner and more ramified shape. It was shown that a change in the domain scale significantly affects the optimal acid breakthrough pore volume for the porosity values ​​considered in this paper, and it turned out that on the “wellbore” scale, breakthrough requires half the amount of acid than on the “core” scale for all F. It was also shown that the optimal acid breakthrough pore volume changes along the domain length by a clear law for all F, which is described by equation  with high approximation coefficients . This equation makes it possible to extrapolate the acid optimal breakthrough pore volumes obtained in laboratory conditions to a larger scale, for example, the scale of the near-wellbore zone.