Fundamentals of Fluid Flow in Porous Media


Chapter 5

Miscible Displacement

Multiple Contact Miscibility Processes

An injected solvent which is not miscible with oil at first contact may achieve miscibility during multiple contacts and mass transfer between reservoir oil and injected fluid. In-situ mass transfer of intermediate molecular weight components between gas and oil phases results in mixtures that are miscible with either the injected solvent or initial oil phases. The multiple contact miscibility are categorized as ‘vaporizing gas drive’ (VGD), ‘condensing’, ‘condensing/vaporizing-gas’ (enriched gas) and CO2 displacement.

The condensing and vaporizing gas drive for enriched gas injection was first proposed and verified by experiments and numerical simulations by Zick in 1986

[1]. Interphase mass transfer of the intermediate components is the key process of the mechanism. Later, analytical theory for the combined condensing/vaporizing mechanism was developed. It can be argued that condensing/vaporizing gas drive is the most common mechanism developed in miscible injection field projects as injected solvents usually contain somewhat light- and heavier-intermediate components.


[1] “Introduction to Chemical Engineering Thermodynamics”, J. M. Smith, H.C. Van Ness, M. M. Abbot


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