Imbibition porous media

Interpretation for irreducible water saturation assumes that the rock is water-wet or mixed-wet (water-wet during drainage but the pore surfaces contacted by oil becomes oil-wet upon imbibition). If a porous medium is water-wet and a nonwetting fluid displaces the water (drainage), then the non-wetting fluid will first occupy the larger pores and will enter the smaller pores only as the capillary pressure is increased. This process is similar to the accumulation of oil or gas in the pore space of a reservoir. Thus it is of interest to estimate the irreducible water saturation that is retained by capillarity after the hydrocarbon accumulates in an oil or gas reservoir. The FFI is an estimate of the amount of potential hydrocarbon in... 

Imbibition The displacement of a non wetting phase by a wetting phase in a porous medium or a gel the reverse of drainage. 

The fractional wettability of the porous medium, defined as a measure of the fraction of the internal surface of the porous medium in contact with one fluid (13) was determined by the USBM method (14). In the USBM method for determining wettability, the logarithm to the base 10 of the ratio of areas under a secondary drainage (A3) and an imbibition capillary pressure (A2) versus water saturation curves is used to define the wettability scale. 

The imbibition of aqueous surfactant solutions into a single cylindrical capillary with walls partially wetted by water is considered in this section. A single capillary is used as a model of a porous medium. 

Imbibition of water is a physical process caused by adsorption of water to hydrophilic ion-groups forming a hydrophilic surface. A porous reservoir medium, consisting of a hydrophilic surface, may contain lipophilic liquid such as oil. When such an oil filled reservoir rock is exposed to water, the water may spontaneously be sucked into the pores and displace the oil. This physical process is a result of forces acting in the individual pores. 

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