This research concluded that, as the concentration of Fe2+ increases in mix-water used in the preparation of cement sheath cubes, the individual performance responses of compressive and tensile strengths decreased, while porosity and permeability increased. This premise contributed to cementing, which means that a high concentration of Fe2+ also caused the failures of wellbore integrity and complete wellbore zonal isolation. Moreover, using hypotheses at the significance level of 0.05 to develop models for the performance responses conducted. These developed models were to help save the time and cost implications of repeating such rigorous laboratory work. In addition, each of the developed models' lack-of-fit p-value is more significant than 0.05, while each of the models' terms' p-value is less than 0.05. Therefore, this research declared the developed predictive models are adequate and robust.