PETE 311 QUIZ 4

capillary pressure

pressure difference between non-wetting and wetting phases

What does capillary pressure physically represent?

Resistance to fluid movement due to surface tension and pore geometry

Applications of Pc data

determines fluid distribution, saturation, recoverable oil, relative permeability, and simulation inputs

drainage

increase in non-wetting phase saturation

imbibition

increase in wetting phase saturation

drainage examples

Hydrocarbon displacing water in water-wet rock

waterflooding an oil reservoir that is oil-wet

gas injection in an oil or water wet reservoir

imbibition examples

accumulation of oil in an oil-wet reservoir

waterflooding a water-wet oil reservoir

accumulation of condensate as pressure decreases in a dew point reservoir

capillary rise

driven by adhesion and surface tension forces

factors affecting capillary rise

interfacial tension, contact angle, tube radius, density difference

Pc = (2σ cosθ) / r

r- smaller radius increases Pc

higher σ increases Pc

Higher θ decreases Pc

hysteresis

dependence of capillary pressure on saturation history

FWL(free water level)

depth where Pc=0

vertical fluid distribution

controlled by density difference and capillary pressure

transition zone

region where water saturation gradually changes

effect of contact angle

Lower contact angle increases displacement pressure and irreducible saturation

effect of interfacial tension

Higher tension increases transition zone thickness

effect of density difference

Smaller density difference increases transition zone thickness