The Leakage Simulation Of Supercritical Carbon Dixoide In A Porous Geological Medium With Low-permeability Layers

The increase of carbon dioxide?CO₂?in the air leads to many environmental problems,such as the rise of sea levels,climate deterioration,and water cycle imbalances.In order to control the greenhouse effect,the CO₂ is pressurized to the supercritical state to be injected into the geological formation.The complex formation and various rock types can hinder the migration movement of CO₂.Consequently,the CO₂ can be dissolved into the brine slowly,and be sealed in the tiny pores,or react with particular rocks to achieve long-term storage.However,on a long-term scale,a large amount of CO₂ accumulates in the geological formation,and there is still a risk of CO₂ leaking through the crack or the oil well wall or even through the cap layer.In this paper,a study of the leakage flow process in this storage is carried out.According to the geometric character,the structure of the geological formation can be seen as a porous medium with low permeability cap layers.?1?Based on geological data of the storage location,setting up a porous media model with low permeability layers.We apply a simplified the model mainly by changing permeability distribution in this media.Relying on Fortran,a high-precision numerical simulation has been set up to simulate the complex flow in this porous media and the streamfunction-vorticity equation is solved by pseudo spectral methods.?2?Based on these different physical models,we analyze the CO₂ leakage flow patterns.Considering different initial CO₂ concentration distribution and multiply cap rock layers,the leakage flow are simulated in different cases.Moreover,the rate,the velocity,the dynamic evolution of leakage drops are analyzed.?3?Geological parameter and CO₂ characteristic both affect the numerical simulation results,in other word,the leakage patterns.Therefore,we analyze the buoyancy coefficient B of CO₂,the dimensionless thickness h of the cap layer,the dimensionless permeability ratio?of the cap layer to the storage layer to study how these parameters influence the leakage process.In short,a high-precision numerical simulation method is used to simulate the migration and leakage of CO₂ in the geological formation.Therefore,the flow characteristics and mechanism of the CO₂ leakage process are revealed,which provides a basis for establishing a quantitative model of leakage,also provides reference value for the practical application of CO₂ geological storage.