1. Chapter 5 Drilling Techniques and Drilling Problems

2. Straight hole Well deviates < 3 deg. per 100 ft (30m)
Cone with a maximum angle of 5 deg

3. If the bit hits a subsurface rock layer with a dip greater than 45 deg
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.

4. Directional 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.

5. Directional Drilling
Directionally drilled wells will usually be drilled according to one of three basic hole patterns.

6. 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”).

8. Uses of Directional Drilling

9. Situation Requiring Directional Drilling

10. 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

11. Downhole hydraulic motors with a “bent sub”

13. Device used to kick off a well

14. Jet bit

15. Jet bit

16. Whipstock

17. Whipstock

18. A steerable downhole assembly is a combination of stabilizers, bent subs, downhole turbine motor, and diamond bit that can maintain, drop, or build angle.

20. Plot of well survey data showing paths of directionally drilled wells

21. Extended Reach Well
and
Horizontal Drain Well

23. Depth of a Well

24. Problems while drilling
Fishing
Stuck pipe
Sloughing shale
Lost circulation
Formation damage
Corrosive gases
Abnormal high pressure

25. Differential sticking of drillpipe because of heavy mud weight

26. Crooked wellbore showing view of “key seated” drillpipe

28. Three types of junk baskets for retrieving foreign objects from hole