706 



Subsurface Geologic Methods 



The difference between the permeability-saturation relationship for 

 water and that for oil and gas must be dependent upon the distribution 

 and the particular location of the fluids in the pores as the saturation 

 changes (fig. 376) . The nonwetting-fluid phases always will tend to con- 

 centrate in the larger pores and in the central parts of these pores, 

 whereas the wetting phase will tend to be retained in the smaller pores, 

 re-entrant corners and crevices, around the points of inter-grain contact, 

 and in those portions of the pore spaces that are less effective for transmis- 



< 



o 



I- 



LiJ 



q: 



1.0 



0.9 



0.8 



0.7 



SAMPLE 4 



K = 79.0md. 



t 0.6 



0.5 



m 

 < 

 ijj 



:e 



UJ 

 Q. 



UJ 0.4 

 > 



< 



0.3 



0.2 



0.0 



o 



iO 20 30 40 50 60 

 WATER SATURATION - PERCENT 



70 



80 



Figure 382. Variation of relative permeability to gas of Big Lake dolomite 

 with connate-water saturation, McElroy field, Texas. 



