1. TRIBOLOGY IN DRILLING OPERATION CHIH LIN, PHD AUGUST 29, 2013

2. OUTLINE Tribology in Drilling Tribology on the rig  Engine  Mud Pump Downhole Tribology  Drillstring Components  Mud Motor  Drill Bit Typical wellbore design

3. WHY TRIBOLOGY FOR DRILLING INDUSTRY Nonproductive time (NPT) caused by preventable tool failures in offshore drilling and completion can cost tens of millions of dollars per year As much as 70% of all energy delivered by drilling equipment is lost through friction (Navarro, AADE-11-NTCE-17, 2011) Friction and drag are serious problems while drilling directional, high angle and extended reach wells Friction torque may exceed the capacity of the drilling rig while drag can severely reduce load transfer to bottomhole assembly (BHA)

4. TRIBOLOGY IN DRILLING Rig Operation WOB RPM Reactive torque Pump pressure Mud rheology Drillstring Tool joint/stabilizer- formation contact Fluid-cutting-filtercake lubrication effect Key seating Hole Bottom Cutter-rock interaction Bit OD-rock contact BHA pendulum contact Stabilizers Bottom Hole Assembly

5. (Sources: Merriam-Webster Visual Dictionary Online) Diesel engine (piston ring, crankshaft, wrist pin, bearings, seals, gears, etc.) Mud pump (valves, bearings, seals, etc.) TRIBOLOGY ON THE RIG Hydraulic rotary table (Akersolutions)

6. Crankshaft bearing Connecting rod Piston rings and liners Valve ENGINE

7. MUD PUMP Helical

8. Roller bearing failureBabbitt bearing failure COMPONENT FAILURES Possible causes of bearing failure Seal failure Contaminated lubricant Excessive vibration Incorrect installation Connecting rod failureCrankshaft failureValve failure

9. Convergent wedge Presence of viscous fluid film Relative velocity LUBRICATION PRINCIPLE Elastohydrodynam ic Lubrication Elastic deformation Convergent wedge deformation Hydrodynamic pressure leakage Journal Bearing (Lasson, 2009)

10. CURRENT PRACTICES TO REDUCE FAILURE Better understanding of the operation and wear mechanisms of bearings and seals through simulation and testing Improved manufacturing process to obtain desirable surface finish and geometry Use of advanced materials What else can you think of?

11. Drillstring Friction Tool joint/stabilizer- formation contact Fluid-cutting-filtercake lubrication effect Key seating DOWNHOLE TRIBOLOGY Tool joint wear Filtercake

12. CURRENT PRACTICES TO REDUCE FRICTION Better hole cleaning (requires extra NPT) Lightweight drill pipe (extra expenses) Use of oil/synthetic based drilling muds or lubricants in water based drilling muds (additional cost) What else can you think of?

13. DOWNHOLE TRIBOLOGY Mud motor  Rotor/Stator interaction  Radial and thrust bearings

14. DOWNHOLE TRIBOLOGY Mud motor failure modes Stator Elastomer Failure Rotor Coating Failure PDC Thrust Bearing Failure Sexon and Cooley, Wear, vol. 267, 2009

15. CURRENT PRACTICES TO REDUCE FAILURE Better bearing materials Improved lubrication What else can you think of?

16. Drill Bit  PDC Bit  Roller Cone Bit  Hybrid Bit  Reamer DOWNHOLE TRIBOLOGY PDC Roller Cone Hybrid Reamer PDC Cutter

17. DOWNHOLE TRIBOLOGY PDC Cutter Failure Roller Cone Cutter Failure Bearing Failure Reamer Cutter WearSeal Wear Seal Failure Failures (Wear and Breakage)  Cutter  Bearing  Seal

18. CURRENT PRACTICES TO REDUCE WEAR Better understanding of the operation and wear mechanisms of bearings and seals through simulation and testing Use of advanced materials What else can you think of?

19. SUMMARY – YOU NEED TRIBOLOGY Applying lubrication principle can reduce friction and improve drilling efficiency, and reduce wear and improve tool life Understanding wear mechanisms can generate insights for better material designs

20. THANK YOU FOR YOUR ATTENTION