Multiple-contact miscibility

Depending on temperature, pressure, and oil and solvent composition, the injected solvent may be completely miscible (first-contact miscible) with the oil or may develop multiple-contact miscibility by continuous... 

Separation Model for the Study of Multiple Contact Miscibility in Rich Gas Drives, Soc. Pet. Eng. J. 1973,147-155. 

Fig. 5.108—Effect of mobile water on oil recovery for CO2 displacements of reservoir crude oil (multiple-contact miscible process), tertiary displacements, water-wet core. ...

Tiffin, D.L. and Yellig, W.F. Effects of Mobile Water on Multiple-Contact Miscible Gas Displacements, SPEJ (June 1983) 447-54. 

The latter quantity is usually determined phenomenologically by measuring displacements of crude oil with carbon dioxide (or other injection fluid) from a long capillary tube (i.e., "slim tube") at a series of successively higher pressures. A plot of displaced oil versus pressure usually has a break at about 95-percent recovery, which is taken as the "minimum miscibility pressure." Often this is not a true miscibility in the correct thermodynamic sense. For example, many crudes contain asphaltenes that precipitate and do not dissolve even after a series of theoretical "multiple contacts" between the crude and the propagating mixture of injection fluid and non-asphaltenic components of the crude. 

There are many attractive features of EOR using CO2. First, carbon dioxide is a proven solvent for reconnecting, mobilizing and recovering waterflood residual oil. It is not completely miscible with most crude oils on first contact, as an ideal solvent is, but many studies show that it can achieve miscible-like displacement efficiency through multiple contacts (partitioning and extraction) with the crude oil (i). 

The oil phase, Soltrol 130, a refined kerosene, was doped with iodated oils of similar molecular structure. The dopants are strong photoelectric absorbers and increase the accuracy of saturation determination by increasing the X-ray attenuation. The refined, nearly single-component, oil was also used to insure complete first-contact miscibility. Because this is a single-component oil, multiple contact developed miscibility is not observed below the miscibility pressure. 

There are, in general, two types of miscible processes. One is referred to as the single-contact miscible process and involves such injection fluids as liquefied petroleum gases (LPGs) and alcohols. The injected fluids are miscible with residual oil immediately on contact. The second type is the multiple-contact, or dynamic, miscible process. The injected fluids in this case are usually methane, inert fluids, or an enriched methane gas supplemented with a C2-C6 fi action. The injected fluid and oil are usually not miscible on first contact but rely on a process of chemical exchange between phases to achieve miscibility. 

The capacity of CO2 to vaporize hydrocarbons is much greater than that of natural gas. It has been shown that CO2 vaporizes hydrocarbons primarily in the gasoline and gasoil range. This capacity of CO2 to extract l drocarbons is the primary reason for the use of CO2 as an oil recovery agent. It is also the reason CO2 requires lower miscibility pressures than those required by natural gas. The presence of other diluent gases such as N2, methane, or flue gas with the CO2 will raise the miscibility pressure. The multiple-contact mechanism works nearly the same with a diluent gas added to the CO2 as it does for pure CO2. Frequently an application of the CO2 process in the field will tolerate higher miscibility pressures than what pure CO2 would require. If this is the case, the operator can dilute the CO2 with other available gas, which will raise the miscibility pressure but also reduce the CO2 requirements. 

Gases or vapours that are water soluble or miscible or that are only soluble or highly reactive in other agents Absorption with multiple surface contact by atomizing liquid with spray nozzle or jet impaction Crabtree ozone analyser or midget venturi scrubber Water, acid, or alkali 5-25 60-100 Venturi scrubber satisfactory if dust is present Atomizer absorber will plug... 

This stochastic model of the flow with multiple velocity states cannot be solved with a parabolic model where the diffusion of species cannot depend on the species concentration as has been frequently reported in experimental studies. Indeed, for these more complicated situations, we need a much more complete model for which the evolution of flow inside of system accepts a dependency not only on the actual process state. So we must have a stochastic process with more complex relationships between the elementary states of the investigated process. This is the stochastic model of motion with complete connections. This stochastic model can be explained through the following example we need to design some flowing liquid trajectories inside a regular porous structure as is shown in Fig. 4.33. The porous structure is initially filled with a fluid, which is non-miscible with a second fluid, itself in contact with one surface of the porous body. At the... 

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