1. PETE Well Drilling
Lesson 5 Hole Problems

2. Lesson 5 - Hole Problems Lost Circulation Stuck Pipe Junk in Hole
Keyseat- Crooked Hole
Differential Sticking
Mechanical Sticking
Junk in Hole
Kicks and Blowouts
Crooked Hole

3. Homework
Read: * Applied Drilling Engineering, Ch. 1 * Definitions HW #2 ADE 1.12, 1.13, due Friday, Sept

4. Hole Problems - Lost Circulation
Indication:
Flow out < Flow in (e.g 400 < 500)
Drop in Mud Pit Volume
Blowout

5. Hole Problems- Lost Circulation
Causes:
High Formation Permeability (e.g. fractures)
Low Formation Pore Pressure
Poor Drilling Fluid Characteristics
Induced Fracturing of Formation From Rapid Pipe Movement

6. Hole Problems- Lost Circulation
Results:
Costly Mud Makeup
Loss of Production
Fire
Loss of Permit to Drill

7. Hole Problems- Lost Circulation
Preventive Measures:
Crew Education
Good Mud Program
Study Wells in Area
…to be prepared

8. Hole Problems- Lost Circulation
Remedial Measures:
Use Lost Circulation Material as Mud Additive (fibrous or granular)
Drill Through Troublesome Interval and Case Off
Decrease Mud Weight
Decrease Circulation Rate

9. Hole Problems - Stuck Pipe (drill pipe, drill collars, casing)
Indication:
Cannot Pick Up Pipe (Venezuela case)
Causes:
Cave - ins
Keyseat - Crooked Hole

10. Hole Problems - Stuck Pipe
Causes, cont’d:
Differential Pressure Sticking
Filter Cake
Deposited AFTER Circulation Stops
- While Still on Bottom

11. Hole Problems - Stuck Pipe
Results:
Fishing Operations
Back off, POH, RIG w/fishing string
Loss of Hole
or at least part of the hole

12. Hole Problems - Stuck Pipe
Preventive Measures:
Use Minimum Mud Weight Required to Control Formation Pressures.
Use Special Drill Collars (spiral)
Use Centralizers on Casing
Periodically Establish Circulation while Running Casing or Drillpipe in Deep Hole

13. Hole Problems - Stuck Pipe
Remedial Measures:
If Circulation Can Be Established:
Erode Mud Filter Cake - at High Fluid Velocity (speed up pumps)
Spot Special Fluid; Oil, Acid
Reduce Mud Weight as Far as Possible
Rotate Pipe - Keep Moving Pipe

14. Hole Problems - Stuck Pipe
Remedial Measures:
If Circulation Cannot Be Established:
Cut Pipe or Unscrew Joint - and Fish

15. KEY
SEAT

16. P1 >> P2 P1 P2

17. F = mN N = DP A F = m DP A Thick Filter Cake Thin Filter Cake
How is filter cake formed?
Pipe Stuck in Wall Cake

18. Hole Problems - Junk in Hole
Indication:
Bit Parts Missing
Items from Surface Dropped into Hole
Erratic Torque

19. Hole Problems - Junk in Hole
Cause:
Negligence of Crew
Result:
Fishing Operation

20. Hole Problems - Junk in Hole
Preventive Measure:
Crew Education
Remedial Measures:
Run Junk Basket
Run Basket with Collapsible Teeth (“Poor Boy” Basket)
Run Magnet

21. Hole Problems - Blowout (oil, gas or water)
Indication:
Returns to Surface after Circulation is Stopped (KICK!)
Well Out of Control - Big Problem!
Lost Circulation . . .

22. Hole Problems - Blowout (oil, gas or water) [surface or underground]
Causes:
Loss of Hydrostatic Head due to Lost Circulation
Poor drilling Fluid
Swabbing Effect while Pulling Drillpipe
Insufficient Mud Weight

23. Hole Problems - Blowout
Results:
Possible Loss of Life and Property
Legal and Financial Problems

24. Hole Problems - Blowout
Preventive Measures:
Crew Education
Be Alert
Blowout Control Equipment on RIG including Pit Volume Indicators

25. Hole Problems - Blowout
Remedial Action:
If on Bottom:
Use proper Mud Weight
Add Lost Circulation Materials
In Extreme Case of Blowout:
May Have to Directionally Drill a Relief Well

26. Hole Problems - Crooked Hole
Indication:
Periodic Directional Surveys
Stuck Drill String
Casing Problems

27. Hole Problems - Crooked Hole
Causes:
Too much Weight on Bit
Dipping Formation
Anisotropic Formation
Too Small Drill Collars
No Stabilizers

28. Hole Problems - Crooked Hole
Results:
Uneven Spacing (on bottom)
Legal Problems
Production Problems
Cementing Problems

29. Hole Problems - Crooked Hole
Preventive Action:
Avoid Buckling of Drill Pipe by using sufficient number of drill collars
Use “Oversize” Drill Collars
Use Reamers and Stabilizers
Start the Hole Vertically

30. Hole Problems - Crooked Hole
Remedial Action:
Plug Back and Sidetrack
Use Whipstock
Use Reamers in 3 Locations

31. Lost Circulation Example
This Example shows how to determine the mud weight that can be supported by the formation and also the mud weight that will control the subsurface pressure.
Well depth = 16,000 ft
Protective casing seat = 12,500 ft
Mud Weight = 17.0 lb/gal
Drillpipe size = 4.5 in.
Hole size, casing I.D. = 8.5 in.
Annulus volume = 0.05 bbl/ft
Water required to fill hole = 20 bbl

32. Before Water
After Water
Water bbls
400 ft
Mud lb/gal
12,500 ft
16,000 ft
BHP = ?
BHP = 13,963 psig

33. Example - Solution
Determine: The effective hydrostatic head and mud weight in lb/gal.
Solution:
Water gradient = * 8.33 = psi/ft
Mud gradient = * = psi/ft

34. Example 3.1 Pressure imposed at total depth:
400 ft of water x psi/ft = 173 psi
15,600 ft of mud x psi/ft = 13,790 psi
Total pressure at 16,000 ft = 13,963 psi

35. Example 3.1 Pressure imposed at the casing seat:
400 ft of water x psi/ft = psi
12,100 ft of mud x psi/ft = 10,696 psi
Total pressure at 12,500 ft = 10,869 psi

36. Before Water
After Water
Water bbls
400 ft
Mud lb/gal
12,500 ft
EMW = lb/gal
10,869 psig
16,000 ft
EMW = lb/gal
BHP = 13,963 psig

37. END of Lesson 5 Hole Problems