Applications Of The Phase Field Theory In The Displacement Process Of Heavy Oil Thermal Recovery

Due to the high viscosity and high flow resistance of heavy oil,conventional oil extraction method is not applicable for exploiting heavy oil.Nowadays,the main method to exploiting heavy oil is thermal recovery method.High temperature steam flooding is a very important technology in the heavy oil thermal recovery.Using the advantage of phase field theory in simulating two-phase interface,I have simulated the movement of the interface between the steam and heavy oil to research the displacement process between the steam and heavy oil.The main works are as the following aspects:(1)Based on the theory of heat and mass transfer in porous media and Darcy seepage equation,combining Cahn-Hilliard phase field equation,and considering the interaction between the velocity field and temperature field,I have established the two-phase incompressible fluid displacement phase field theory model in porous media.Reservoirs flow field is divided into two regions—the steam zone and the oil zone—by the oil-steam moving interface,fluids flow driving the two-phase interface moves together.Considering the steam and heavy oil with different viscosity and mobility,I have introduced the approaches to deal many important parameters of the two-phase interface between steam and heavy.(2)Using finite difference method to discrete and calculate the flow field equation and phase field equation,I have simulated the displacement process between heavy oil and steam.By comparing the simulation results of phase field theory to the theoretical analysis results,I have verified the correctness and applicability of two-phase displacement phase field theory model.(3)In this paper,I have used phase field theory to simulate the flow characteristics of two-phase flow field in reservoir.Chosen the two-dimensional DC flow field to be the computational domain,I have used phase field theory to simulate the two-phase displacement process in reservoir,the movement of two-phase interface,the temperature distribution of oil layer in thermal recovery,and analyzed the effect of thermal recovery method on improving heavy oil exploitation.The hot steam is injected into the oil layer,by heat transfer,heats the heavy oil,increases the temperature of heavy oil,to reduce the viscosity of heavy oil,improves the flow capacity of heavy oil,and then improves the efficiency of the exploitation of heavy oil.(4)In this paper,I have analyzed the effect of thermal recovery method on heating heavy oil and the effect of steam on displacing the heavy oil under different steam injection condition.The difference of injection pressure is the key point of discussion.I have analyzed the maximum displacement distance in steam flooding,the temperature variation in reservoir,and the viscosity change of heavy oil,got the most reasonable injection pressure,provided a better basis for improving the efficiency of thermal recovery and optimizing steam injection program.