Theoretical Research Of Porous Flow For Condensate Gas With Phase Change

Theory of flow in porous media for condensate gas with phase change was studied in this thesis. The main works of this thesis includs:1.An effective experiment method is brought out to study distribution and flow rules of condensate near well bore region in this paper. The real porous media is modeled by the phantom micromodel with similar pore structure. The experiments were carried out in porous media under high temperature and high pressure to observe the forming, distribution and flow rules of condensate. The results indicate that the condensate accumulate easily at small pore, stagnant pore, pore throat and pore surface, which evolves to a plug gradually. It is difficult to accumulate for the condensate in big pore. The flow manner of the condensate includes mainly three styles: schlep by gas, crawl along pore wall and plug flow.2.The flow pattern observed in micromodel test could be divided into two half-cycles: namely open half-cycle and closed half-cycle. The evolution equations were set up to describe the spatial fluid distribution at any point in time using perturbation theory. A tank with volume similar with the gas pore volume and a conduit is to model condensate gas flow in pore. The average gas pressure is update using the mass balance equation applied to the tank. The pressure drop is calculated using the viscous flow equation applied to the conduit. The microcosmicmathematical model for Condensate gas flow in pore was set up.3. According to the result of the numerical simulation, the relationship between relative permeability and interface tension, saturation, velocity as follows:The relative gas permeability predicted by the model increases with the increasing demensionless rate ; The predicted gas relative permeability decreases, the predicted condensate relative permeability increases with the increasing condensate saturation; the predicted gas relative permeability decreases, the predicted condensate relative permeability increases when IFT increases. Based on the relations between relative permeability and interface tension, saturation, velocity, the simple models of the relative permeability were set up. The relative permeability predicted by the simple models accords with the experimental data, which shows that the simple models is high precision.4.New momentum equations are set up, considering Non-Darcy flow effects, the phase change between condensate gas and condensate, phase velocity and fluid character, based on a simple model of three zones. Interfacial drag force and capillary pressure were introduced into the new model. At the same time energy equations are deduced considering latent heat of vaporization and fluid-solid heat coupling. A mathematical model of multiphase flow in porous media with phase change is set up in this paper combining new momentum equations, new equations of energy with equations of mass conservation. The process of depletion type condensate gas was simulated using the program for a mathematical model of multiphase flow in porous media with phase change.