298 



Subsurface Geologic Methods 



Cores may be analyzed on location or preserved for off-location 

 analyses. Methods of core preservation include quick-freezing and sealing 

 in airtight containers such as small-diameter plastic tubes. These tubes, 

 which may be obtained to fit the core diameters very closely, reduce 

 the void. If the void is sufficiently small, cores may be preserved for 

 indefinite periods in airtight containers. Pressure is created in the con- 

 tainer by the evaporation of a very small amount of the fluids in the 

 outer portion of the core; only the center of the core is used for satura- 



Figure 125. Summary of core data, gas reserve, and recoverable gas for well A. 

 Capacity is sufficiently high for commercial gas production. Recoverable gas 

 volume has been calculated to a residual pressure of 200 p.s.i. 



