Figure 25-7. Correction of core dip for well deflection. 



dips for well deflection. In this instance, the hole must be considered vertical 

 when the dip is measured. Then the whole system is tilted until the well is in 

 its true position and the new attitude of the bedding plane determined. 



This problem is very simply solved by the use of polar projection and 

 rotation of the sphere. In Figure 25-7 the well is placed at the center of the 

 net in a vertical position. The well may be considered the normal to the core 

 top, now in a horizontal position. The observed dip in the core is measured 

 from the core top. The normal to the bedding plane is represented by d, 20 

 degrees from center in a direction opposite azimuth 259 degrees. When the well 

 is tilted into its true position, azimuth 155 degrees is placed on the E point, and 

 the sphere is rotated 55 degrees. While w moves to w' position, d moves to d', 



539 



