In this paper, quantitative thermodynamic parameters are quantified and applied to evaluate the oil-gas miscibility developments and to determine the minimum miscibility pressures (MMPs) from the bulk to nanometer scale. First, mathematical formulations of the Gibbs and interfacial energies and the solubility parameter in the bulk phase and nanopores are derived coupled with a modified equation of state and semianalytical correlation. Second, the calculated Gibbs and interfacial energies and solubility parameters are utilized to analyze the miscibility development, based on which specific thermodynamic MMP criteria are developed. The calculated MMPs from the new thermodynamic MMP criteria are compared with and validated by the measured MMPs of a total of 55 dead and live oil-pure and impure gas systems in the bulk phase and nanopores at different conditions. Moreover, the effects of temperature, oil and gas compositions, and pore radius on the MMP are evaluated. It is found that the miscibility interpretation may be in variation based on different thermodynamic properties even though the miscible state performs similarly in the macroscopic perspective. Three new thermodynamic MMP criteria are developed based on the first derivatives of the Gibbs energy and solubility parameter and the second derivative of the interfacial energy with respect to pressure, which are linearly regressed and extrapolated to determine the MMP with a critical linear correlation coefficient. The three thermodynamic criteria are found to be accurate and physically correct for the MMP determinations of various oil-gas systems in the bulk phase and nanopores at different conditions, wherein the solubility parameter and interfacial energy criteria are slightly better than the Gibbs energy criterion. Overall, the miscibility is strongly dependent on the temperature, oil and gas compositions, and pore radius.