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Lesson 5 Hole Problems

PETE 411 Well Drilling. Lesson 5 Hole Problems. Lesson 5 - Hole Problems. Lost Circulation Stuck Pipe Keyseat- Crooked Hole Differential Sticking Mechanical Sticking Junk in Hole Kicks and Blowouts Crooked Hole. Homework.

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Lesson 5 Hole Problems

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  1. PETE 411Well Drilling Lesson 5 Hole Problems

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

  3. Homework Read:*Applied Drilling Engineering, Ch. 1*DefinitionsHW #2 ADE 1.12, 1.13, 1.14 due Friday, Sept. 13. 2002

  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) • Returns to Surface after Circulation is Stopped (KICK!) • Well Out of Control - Big Problem! • Lost Circulation . . . Indication:

  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 • Use proper Mud Weight • Add Lost Circulation Materials Remedial Action: If on Bottom: 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 • 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 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.

  32. After Water Before Water Water - 20 bbls 400 ft Mud - 17.0 lb/gal 12,500 ft 16,000 ft BHP = 13,963 psig BHP = ?

  33. Example - Solution Determine: The effective hydrostatic head and mud weight in lb/gal. Solution: Water gradient = 0.052 * 8.33 = 0.433 psi/ft Mud gradient = 0.052 * 17 = 0.884 psi/ft

  34. Example 3.1 Pressure imposed at total depth: 400 ft of water x 0.433 psi/ft = 173 psi 15,600 ft of mud x 0.884 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 0.433 psi/ft = 173 psi 12,100 ft of mud x 0.884 psi/ft = 10,696 psi Total pressure at 12,500 ft = 10,869 psi

  36. After Water Before Water Water - 20 bbls 400 ft Mud - 17.0 lb/gal 12,500 ft EMW = 16.72 lb/gal 10,869 psig 16,000 ft EMW = 16.78 lb/gal BHP = 13,963 psig

  37. END of Lesson 5 Hole Problems

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