Chemical–Gravity–Thermal Diffusion Equilibrium in Two-Phase Non-isothermal Petroleum Reservoirs

Abstract

The initial state of hydrocarbon mixtures in petroleum reservoirs is the result of equilibrium among several forces, the most important of which are the chemical forces arising from chemical potential gradients of the molecular species in the petroleum accumulation, the gravitational force arising from the gravitational acceleration, and the thermal diffusion forces arising from temperature gradients. The equilibrium among these forces determines the state of pressure and a compositional gradient and the creation of a gas–oil contact (GOC) in a stationary reservoir along with the changes in other physical properties. Accurate modeling of these changes in the development of a proper stationary model for the reservoir simulation initialization leads to more realistic predictions of the future behavior of petroleum reservoirs. This is important especially when phase behavior is important in designing, modeling, and predicting the performance of the processes used to maximize the oil recovery, such as in deal...