600 



20 



18 



16 



14 



12 



0? 10 



8 



6 



4 



2 







russell-dickey. POROSITY AND PERMEABILITY [Ch. 32 



-U (jS w )(ycosd) 



_7 -Variation in interfacial 

 .[tension (dynes/cm 



10 20 30 40 50 60 70 80 90 100 

 S w 

 2( w. rrX - Variation in- 



6- Variation in. 



jpj.\ I i i i " "~ i i 



4o^-|- contact angle (degrees)- 



.0=3O< 



10 20 30 40 50 60 70 80 90 100 

 S w 

 4.0 nsn i /"-Variation in porosity- 



(fractional)- 



10 20 30 40 50 60 70 80 90 100 



S w 



10 20 30 40 50 60 70 80 90 100 

 S w , saturation of wetting phase 

 in percent of pore volume 



Fig. 9. Effect of different interfacial tensions, contact angles, permeabilities, and 

 porosities on the capillary pressure-water saturation curve. (After Rose and 



Bruce, 1949, p. 131.) 



Woodbine sand from the Hawkins pool, with permeabilities between 

 2,000 and 6,000 millidarcys, while "Rangely" applies to several samples 

 of Weber sand with permeabilities ranging from 1 to 10 millidarcys. 

 Each of these samples has its own distinct capillary pressure-satura- 

 tion curve. When the j function is calculated for each capillary pres- 

 sure and plotted against the water saturation at that pressure, it is 

 found that all samples of the same rock give nearly identical curves, 

 but that curves of different rocks are different. The authors point out 

 that this suggests very strongly that each reservoir rock is character- 

 ized by some particular texture which persists through variations in 

 grain size. Apparently this constant factor is expressed by the square 

 root of the porosity divided by the permeability. 



