Miscellaneous Subsurface Methods 519 



spudding bit. The resulting increase in angle derived from the whipstock 

 run usually will sidetrack the plug. A new technique has been used re- 

 cently in running whipstocks when a maximum deflection is desired. A 

 roller reamer is made up above the whipstock bit when a full-gauge 

 whipstock is used (fig. 248). This set-up prevents the tendency of the 

 bit to decrease deflection as it drills by the bottom of the whipstock. This 

 set-up has been used in a number of cases to sidetrack plugs when ordi- 

 nary methods failed. 



It is good practice to check the results of a deflecting-tool run by 

 taking a reading in the "rathole." When a small-diameter "rathole" is 

 made, a small-type single shot should be used to eliminate the danger of 

 sticking the single shot in the well. Some operators prefer to make a 

 drift and direction determination after the "rathole" has been reamed. 

 If it is found that the tool run has been unsuccessful, another tool may be 

 set immediately for correction, or the deflected hole sidetracked by drilling 

 with a sharp bit used below a long drill collar. 



Orientation of a deflecting tool consists in making the tool face in the 

 direction desired by the operator as it is landed at the bottom of the hole. 

 Two methods are in general use for accomplishing this orientation. 



The drill-pipe alignment method is used whenever a tool is set in a 

 well which is nearly vertical at the setting point. It also is used for 

 orientation at shallow depths, as it is more rapid than the bottom-hole 

 orientation method. The system of orientation requires a crew of two 

 engineers. They use drill-pipe clamps, a sighting telescope, and a sight- 

 ing bar (fig. 247) . After the tool has been made up on the drill pipe, it is 

 faced in the direction in which it is desired to land it at the bottom of the 

 well. A sighting bar is placed in an orienting clamp, which is afl&xed to 

 the drill pipe just above the deflecting tool and sighted at one of the 

 derrick legs. The telescope is placed in a drill-pipe clamp affixed to the 

 upper end of the drill-pipe stand. The telescope is sighted downward 

 along the drill pipe. This upper clamp is adjusted so that the telescope 

 cross hair is aligned with the sighting bar. Then the telescope is removed 

 from the upper clamp. The lower clamp is removed, the pipe is lowered 

 into the well, and the sighting bar is placed in the same clamp from 

 which the telescope was removed. The bar is sighted upon from above in 

 the same manner as before. This process is repeated until the deflecting 

 tool is near bottom. The sighting bar is placed in the last clamp and the 

 drill pipe turned until the bar again is sighted at the same derrick leg. 

 Thus, the tool is faced on bottom in the same direction as it was at the 

 surface. Briefly stated, a line of sight is projected upward in a vertical 

 plane to the top of each succeeding stand of pipe as the tool is lowered 

 into the well. In practice the orientation by this method is very rapid 

 and highly accurate (fig. 249). 



The other orientation method extensively used is called the "bottom- 

 hole-orientation system." It is used in wells that have more than two 



