Here we report comprehensive dissolution rate measurements of carbonate minerals at reservoir storage conditions with temperature T up to 373 K and CO2 pressure p up to 10.0 MPa in two reactor configurations in order to investigate the impacts of brine chemistries and realistic organic surface contaminants on the dissolution kinetics of carbonates. Using a batch reactor implementing the rotating disk technique, surface reaction rates of non-porous carbonate minerals were obtained by eliminating the impacts of transport effects for a range of CO2-acidified brine systems including sodium chloride, sodium bicarbonate, magnesium chloride and a multicomponent brine system based on a specific Middle Eastern subsurface brine. Experimental results show significant reductions in reaction rates in (CO2 + H2O + NaHCO3) systems where no measurable dissolution rates were observed at a salt molality m of 1.0 mol·kg-1. The measured reaction rates were subsequently compared to predictions from published models derived from (CO2 + H2O) systems at comparable experimental conditions. The impacts of realistic surface contaminants were also studied in the batch reactors at carbon storage conditions at CO2 pressure of up to 10.0 MPa. Calcite surfaces were treated with fatty acids (such as stearic and oleic acids) and crude oil. Following surface treatments, significant changes in the initial wetting property of the mineral surfaces (from water-wet to oil-wet) were observed. Further, changes in mineral surface morphologies upon reaction with CO2-saturated solutions were characterized using optical microscopy. The impacts of brine chemistry and surface contaminants were also investigated in flow reactor setups using cylindrically-shaped calcite channels. These flow measurements were performed at laminar flow conditions to eliminate possible film destruction due to mechanical effects present in the batch reactor setup. In addition, a variation in saturation states is expected across the dissolution channels. In these flow studies, while we observe that the impacts of surface contaminants were negligible, brine chemistry had a significant impact on measured reaction rates.