文档介绍：Chapter 5 Drilling Techniques and Drilling Problems
Well deviates < 3 deg. per 100 ft (30m)
Cone with a maximum angle of 5 deg
Straight 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.
A well with an excessive angle in it that has not been drilled on purpose that way is call a crooked hole.
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.
Directional Drilling or Deviation Drilling
Directional Drilling
Directionally drilled wells will usually be drilled according to one of three basic hole patterns.
Directional Drilling
After making an initial deflection from vertical, the well may be drilled to the target , or deflected once more to allowed the bottom of the
hole to be drilled
vertically
(“double dogleg”).
Uses of Directional Drilling
Situation Requiring Directional Drilling
Directional Drilling
The deviation begins when the hole is deflected using one of several techniques:
(1) downhole hydraulic motors with a
“bent sub”
(2) jet bits
(3) whipstocks
Downhole hydraulic motors with a “bent sub”