A method to measure acid diversion efficiency in rock samples. The method includes measuring a first porosity and a permeability of the rock samples. The method includes flooding a core region of the rock sample with a hydrochloric acid (HCl) system to create a wormhole, wherein during the flooding the HCl system penetrates from a first end of the rock sample to a second end of the rock sample to form the wormhole. The method includes measuring a second porosity, a pore size distribution, and a diffusion tortuosity of the rock samples with NMR. The method includes establishing a diversion index (DI) based off a ratio between the diffusion tortuosity in a first direction and the diffusion tortuosity in a second direction. The method includes determining the acid diversion efficiency based off the diversion index.