540 



Subsurface Geologic Methods 



sissippi and the Cimarron rivers at various points are examples. An oil 

 structure beneath Lake Centralia in the Salem, Illinois, field was devel- 

 oped with wells spaced at bottom by slant drilling. This is an outstand- 

 ing example of directional drilling in hard-rock country. The average de- 

 flection of 250 feet was attained without difficulty. 



Other works of man present similar opportunities for the use of slant 

 drilling. Deep-water ship channels, dredged turning basins, wharves, and 

 transit sheds, as well as industrial sites, such as steam-generating plants, 

 ship yards, dry docks, and manufacturing establishments, would have pre- 



FiGUKE 266. Wells drilled to produce oil beneath harbor area of Long Beach, Cali- 

 fornia. Many wells shown in this figure are directional. 



vented development of the multiple-zoned oil reservoir beneath Long 

 Beach harbor, California (fig. 266) . By carefully planned directional 

 wells drilled in cylinders the whole harbor area is being drained of the 

 subsurface oil without disturbing the expensive surface installations. Pro- 

 duction of oil from beneath the large Navy establishment at Roosevelt 

 Base has not been hampered by the repair yards and graving dock at the 

 surface. Oil is produced through directed wells, which honeycomb the 

 underground formations. 



A spectacular example of this type of work is offered by the produc- 

 tion of oil from under the capitol and other state buildings in the heart 



