Reactive Flow Simulation In CO₂ Flooding Process For Enhanced Oil Recovery

CO₂ EOR?Enhanced Oil Recovery?has been commonly applied in North America and other parts of the world.CO₂ can be very effective in terms of displacement efficiency but due to low density and viscosity,its volumetric sweep efficiency is low,thereby lowering the overall sweep efficiency of the process.On the other hand,injection of CO₂ can affect the mineralogy of the reservoir;causing mineral dissolution and precipitation which could cause damage to the reservoir.Two methods to combat CO₂ sweep efficiency problems are investigated in this thesis.One method is by mobility control though the use of CO₂ foams and another is conformance control using CO₂-triggered gels.CO₂ foam and gel models were built and verified by experiments and parameters were matched.Experimental and modeling results indicate that CO₂ foam is more effective at reducing the mobility and relative permeability of CO₂ than WAG?water alternating gas?.When CO₂ dissolves in the formation water it can lower the pH which can trigger the reaction of PAM,Resorcinol,Methenamine to form gel.In sandpack flooding tests,this gel proved to be effective at blocking the high permeability layers,causing CO₂ to flow to the lower permeability layers and hence increase the volumetric sweep efficiency.In addition,a CO₂-rock water reaction model was built to investigate mineral reactions during CO₂ flooding.Experimental and modeling results indicate that CO₂injection can trigger the dissolution of some minerals and precipitation of others in a sandstone rock sample.The effect of CO₂ induced geochemical reaction is dependent on reservoir type and the properties of the formation water.