Dimethyl ether (DME) is a widely used industrial compound,and Shell developed a chemical EOR technique called DME-enhanced waterflood (DEW).DME is applied as a miscible solvent for EOR application to enhance the performance of conventional waterflood.When DME is injected into the reservoir and contacts the oil,the first-contact miscibility process occurs,which leads to oil swelling and viscosity reduction.The reduction in oil density and viscosity improves oil mobility and reduces residual oil saturation,enhancing oil production.A numerical study based on compositional simulation has been developed to describe the phase behavior in the DEW model.An accurate compositional model is imperative because DME has a unique advantage of solubility in both oil and water.For DEW,oil recovery increased by 34％ and 12％ compared to conventional waterflood and CO2 flood,respectively.Compositional modeling and simulation of the DEW process indicated the unique solubility effect of DME on EOR performance.