3Straight hole Well deviates < 3 deg. per 100 ft (30m) Cone with a maximum angle of 5 deg
4A well with an excessive angle in it that has not been drilled on purpose that way is call a crooked hole.If the bit hits a subsurface rock layer with a dip greater than 45 deg., the bit tends to be deflected down dip. If rock layer dip less than 45 deg., the bit tends to be deflected updip.
5Directional Drilling or Deviation Drilling Modern rotary rigs can be controlled so that the well is drilled out at a pre-determined angle during directional or deviation drilling and ends up in a pre-determined location called target.
6Directional Drilling (Patterns) Directionally drilled wells will usually be drilled according to one of three basic hole patterns.
7Directional Drilling (Patterns) After making an initial deflection from vertical, the well may be drilled to the target, or deflected once more to allowed the bottom of thehole to be drilledvertically(“double dogleg”).