300 



Subsurface Geologic Methods 



data should be a part of every core-analysis report made on sand samples. 

 Clean, porous limestones usually show the same permeability to water 

 as to dry gas because the measuring fluid does not react with the sample. 

 Permeability may be measured parallel or vertical to the bedding 

 planes of the formation. Vertical permeability should be measured for 

 all formations having fluid contacts because of the importance of selecting 



Figure 126. Core-log of well B. 



the completion zone least likely to be affected by fluid coning. (See figs. 

 126 and 127) . The degree of coning of water or gas is a function of the 

 pressure distribution and the horizontal and vertical permeability ratios 

 and may be calculated for any point in a thick formation if complete 

 permeability data are available. ^^ Core-analysis data may be used to cal- 



' Caran, J. C, and Caran, R,, op. cit. 



