Defined retrograde

Stanghellini et al. [122] have carefully defined the most common abnormalities of phase III activity and other abnormal motility patterns that occur in patients with chronic intestinal pseudoobstruction, who often suffer from bacterial overgrowth [113], This concerns phase III with abnormal migration (stationary or retrograde) and with abnormal isotonic component, abnormal burst activity, and a failure of the postprandial pattern. 

We will first consider phase diagrams. Then we will define the critical point for a two-component mixture. This will be the correct definition for multicomponent mixtures. Also, we will look at an important concept called retrograde condensation. Then the pressure-volume diagram will be discussed, and differences between pure substances and two-component mixtures in the two-phase region will be illustrated. Finally, the effects of temperature and pressure on the compositions of the coexisting liquid and gas will be illustrated. 

There are five types of reservoir fluids. These are usually called black oil, volatile oil, retrograde gas, wet gas, and dry gas. The five types of reservoir fluids have been defined because each requires different approaches by reservoir engineers and production engineers. 

As a practical matter, when producing gas-oil ratio is above 50,000 scf/STB, the quantity of retrograde liquid in the reservoir is very small and the reservoir fluid can be treated as if it were a wet gas (defined later). 

A set of equations known collectively as gas material balance equations has been devised to determine original gas in place and predict gas reserves. These equations were derived for dry gases and can be used for wet gases, if care is taken in defining the properties of the wet gases. The equations are applicable to retrograde gases only at reservoir pressures above the dew point. 

The pressure at which this dissociation is predicted to occur is called the hydrate pseudo-retrograde pressure at T. Pseudo-retrograde behavior is defined as the disappearance of a dense phase upon pressurization, which is counter-intuitive. This behavior resembles, but is not strictly the same as, vapor-liquid retrograde phenomena (de Loos, 1994). 

Sawchenko PE, Swanson LW (1981) A method for tracing biochemically defined pathways in the central nervous system using combined fluorescence retrograde transport and immunohistochemical techniques. Brain Res 270 31-51. 

In other words, retrograde condensation is defined as the formation of liquid by an isothermal decrease in pressure or an isobaric increase... 

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