Each of the foregoing solutions to the off-shore location problem, with the 

 possible exception of a shallow-water drilling barge which can be moved from 

 one location to another with relative ease, involves a great deal more expense 

 and labor than a similar on-shore location, and because of this fact, the maximum 

 possible use must be made of each established off-shore location. Most of these 

 locations are currently designed to accommodate a number of wells all drilled 

 from the same surface location. The platform or island is usually so located 

 that one of the wells is a straight hole. The remainder of the wells are direction- 

 ally drilled to bottom-hole targets that are in accord with the established well- 

 spacing pattern for the field. All the wells drilled from these off-shore locations 

 are usually drilled with the same drilling rig — the derrick being movable, or the 

 crown block and the rotary table both being movable. 



Figure 32-5 illustrates a typical off-shore platform under contruction in 

 the Gulf of Mexico. This derrick and platform will be used to drill 6 wells, 5 

 directional and 1 straight. The LST, which will be hooked up to the structure, 

 will be used as a housing and maintenance unit for the drilling crew and as 

 storage for drill pipe, casing, drilling mud, and other material. 



Figure 32-4. Directional drilling of a relief well to control a well which is blowing wild. 



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