Miscellaneous Subsurface Methods 



543 



so it was necessary to turn the courses of both wells in that part of their 

 courses where the drift was greatest. Specialized directional crews super- 

 vised the operations on both wells, bottoming one well 20 feet and 

 the other 40 feet from their exact objectives. Considering the difficulty 

 of the work the record made was very good. The wells averaged 19 

 days each in drilling, or 170 feet of hole made each day. Seventeen de- 

 flecting tools were set for an average of 8^ tools to the well. Casing was 

 run without difficulty and both wells now are producing. Obviously the 

 oil from this lease never could have been produced without directional 

 drilling. 



Don 



HORIZONTAL DEVIATION 



□DDD 



Figure 268. Exploratory directional well drilled under residential district of a city. 



An interesting example of exploratory directed-drilling operations is 

 illustrated in figure 268. It was suspected that an oil structure existed 

 at about 6,000 feet below the residential district of a city. It was im- 

 possible to set up a derrick and drill vertically to explore the formation. 

 A surface location was chosen about fifteen city blocks from the proposed 

 bottom of the well. Leases were secured from each individual lot owner 

 before any actual drilling could be started. Since the well was located 

 near a city hospital, it was necessary to completely sound proof the rig. 

 Deflection was started at about a 600-foot depth by setting an Eastman re- 

 movable whipstock. A number of different types of drilling bits were 

 used at rotary speeds varying from 50 to 100 r.p.m. and with drilling 

 weights from 3 to 14 points. Drift and direction readings were taken by 

 regular single shots run in open hole on sand line and by small single 



