Gases such as carbon dioxide, nitrogen, and methane that can be present in a steam-assisted gravity-drainage (SAGD) steam chamber, but do not condense into the liquid phase to any large degree at reservoir conditions, are referred to as noncondensable gases (NCGs). The coinjection of NCGs with steam during SAGD results in changes in production rate, total oil recovery, and the amount of steam required to mobilize the bitumen in place. To investigate the impact of NCGs on SAGD performance by means of numerical simulation, it is important to model gas solubility in both bitumen and water accurately. This study presents a systematic approach to predict the K-values for the gas-bitumen and gas-water phase equilibria over a wide range of pressures and temperatures.