SOUTHERN HORIZONS 



rushes to the surface, where, the pressure being re- 

 moved, it escapes as a gas. But still deeper within the 

 earth, where the pressure becomes as high as a thou- 

 sand pounds, then the liquefied natural gas again be- 

 comes a gas, or, as the chemists say, it re-enters the 

 vapor phase. 



When such a deeper reservoir is tapped, the liquefied 

 gas reappears in the petroleum mixture only at the 

 point when just the right combination of pressure and 

 temperature is reached. We cannot control the under- 

 ground temperature but we can maintain the pressure 

 above that saturation point which holds the hydrocar- 

 bons in the gaseous state. 



For twenty years gas has been returned to oil wells 

 to maintain the underground pressure so that as much 

 petroleum as possible can be brought from the reser- 

 voir to the surface. Cycling a gas-condensate is not quite 

 so simple. The rich gases from underground are col- 

 lected and are literally scrubbed with an absorption oil 

 which sops up the heavier hydrocarbons which are then 

 removed by distilling. The denuded oil goes back to 

 the absorbers while the stripped dry gas is compressed 

 again and returned to the reservoir. The recovered 

 condensate, distilled out of the absorption oil, is then 

 processed by regular refinery methods, to gasoline, 

 kerosene, and heavy oil fractions, and the gases butane, 

 propane, and ethane are separated out for enriching 



260 



