

SHI P-TYPE— FLOATI NG 



SEMI-SUBMERSIBLE 



J74'Xro'X20'| BOTTOM 



SUBMERSIBLE 



JACKUP 



Figure 6. Schematic drawings of typical rig types. By permission of Richard J. Howe, 

 Humble Oil and Refining Co. 



platform. The major problem appears to be one of 

 economic rather than technologic limitations. 



One of the more recent achievements has been 

 the installation of fixed production platforms in 

 the frigid waters of Cook Inlet, Alaska. These 

 platforms must withstand daily tides of more than 

 25 feet, with tidal currents of up to eight knots, 

 which in the winter move pack ice up to six feet 



thick past the installation four times a day. Each 

 of these platforms costs more than $10 million— an 

 expenditure for a stable base for drilling and 

 production which is essentially free on land. Well 

 completions completely underwater would elimi- 

 nate much of the need for costly fixed platforms; 

 but it is obvious that such completions pose 

 significant problems in meeting requirements, and 



VII- 206 



