Thermal Fluid-structure Coupling Characteristics Of Porous Media Based On COMSOLL

Since entering the 21 st century,China’s economy has developed rapidly,energy consumption has grown rapidly,and conventional energy has been exploited to the limit.The utilization and development of unconventional energy has become more and more important.As an important part of unconventional energy,heavy oil and super heavy oil are very urgent to be exploited and utilized.Due to the high viscosity,unfavorable exploitation and low recovery of heavy oil and super heavy oil,how to efficiently and economically develop and recover heavy oil and super heavy oil is a problem worthy of study.In the process of heavy oil production,it is necessary to inject high temperature fluid into the reservoir,which will reduce the viscosity of heavy oil,but at the same time will heat the rock skeleton of porous media in the reservoir,resulting in deformation and displacement of the rock skeleton,resulting in deformation and failure,affecting the porosity and permeability of porous media in the reservoir.Based on heat and mass transfer,seepage mechanics and rock and soil mechanics,combined with numerical simulation,this paper studies the thermal fluid-structure coupling characteristics of porous reservoir media in heavy oil thermal recovery,and analyzes the factors affecting the thermal fluid-structure coupling of porous media.First of all,this article is based on heat and mass transfer,thermodynamics,fluid mechanics and the basic theory of rock mechanics and other related disciplines,considering elastic deformation and stress distribution of reservoir porous media,seepage of heavy oil is heated,and internal factors such as heat conduction and thermal convection of the porous media,set up in the process of thermal recovery of heavy oil reservoir porous media fluid-solid coupling mathematical model of heat flow.Secondly,taking the heavy oil reservoir of L oilfield as an example,a two-dimensional simplified model of the heavy oil reservoir was established according to REV research scale,and COMSOL Multiphysics software was used to calculate and solve the numerical model of the reservoir porous medium.The influence of inlet temperature,inlet pressure,steam injection time and porous medium permeability on reservoir during heavy oil thermal recovery was investigated.The results show that the displacement and deformation of reservoir porous media and outlet temperature increase with the increase of steam injection time.The heat transfer rate and displacement in porous media increase with the increase of permeability and inlet pressure.Increasing the inlet temperature will lead to a rapid increase in the displacement and deformation of the reservoir porous medium,but a slow increase in the heat transfer rate.Finally,a 50 m×50 m macro numerical model of heavy oil reservoir was established based on COMSOL Multiphysics software,and the coupling effect among temperature field,seepage field and deformation field occurred in the porous medium of the reservoir during heating was numerically analyzed.The results show that the changes of heavy oil reservoirs with different porosity are different.The higher the porosity is,the faster the fluid flow rate and the higher the heat transfer rate are.During the heating process,the temperature field,seepage field and deformation field of the heavy oil reservoir change dramatically,and the change trend is basically consistent with the conclusion of the model based on the characterization unit.After comparison,it is found that the model based on the characterization unit is more precise in the study of reservoir porous media,and the conclusions obtained are more accurate.It provides feasibility verification for the study of porous media in reservoir based on REV micron scale and theoretical guidance for the improvement of thermal recovery technology.