The Northern Niagaran Pinnacle Reef Trend (NNPRT) has generated significant oil and gas production in Michigan. The best reservoir rock in the Reef Trend reservoirs are from porous and permeable dolomite of the Guelph Dolomite. Low-to-non reservoir limestone occurs interstratified with reservoir dolomite in many locations. This study utilizes available cores data, thin section Petrographic Image Analysis (PIA), Mercury Injection Capillary Pressure (MICP) and a newly developed Niagaran Reef depositional model (Rine, 2015) to characterize the distribution of pore geometry within each dolomitized Niagaran Reef Complex (Brown Niagaran - Lower Salina Group) reservoir facies and lithofacies. This study shows that three distinct pore types are present in dolomitized Niagaran Reef Complex Reservoirs: interparticle (intercrystalline), separate vugs and touching vugs. Intercrystalline porosity is the most predictable pore type in dolomitized reef reservoirs where a high correlation in porosity and permeability occurs. Both separate vugs and touching vugs pore types possess a low correlation between porosity and permeability. A new method to describe the uniformity of pore geometry using Relative Standard Deviation (RSD) allows for more reliable characterization of petrophysical properties and permeability prediction from well log-derived porosity.