The following table lists those problems commonly encountered in drilling extended reach (ERD) and horizontal wells and recommendd precautions.
Inefficient Hole Cleaning & Reduced Borehole Stability
- Maintain high annular velocity, use turbulent flow pattern wherever possible
- Use low rheology fluid (horizontal sections)
- Use extended rheology muds for high angle 12.1/4in and larger hole sections
- Pump in/out of the hole - rotate where possible
- Perform frequent wiper trips (every 500ft or as hole conditions dictate)
- Monitor drilled cuttings for sign of caving.
Poor Toolface Control - Weight Stacking
- Monitor torque closely
- Use single bend steerable systems
- Drill in rotary mode as much as possible
- Orient after connections
- Use water-melon profile stabilisers
- Minimise heavy BHA components
- Monitor helical buckling of drill pipe in orienting mode.
Casing Wear-Excessive Torque & Drag
- Use minimum HWDP - smooth hardfacing only
- Install flowline magnets - record metal recovered twice daily
- Record torque values at the shoe on every trip
- Wiper trip at first signs of increasing torque/drag
- Keep BHA as light as possible.
Drill String Failures
- Ensure full inspection prior to well
- Perform visual inspection on every trip
- Monitor rotary torque closely
- Ensure adequate back-up equipment availability
- Perform full inspection of drill string after completion of the well.