Wednesday, 8 November 2017

QUICK IMPORTANT TIPS ABOUT DRILLING PROBLEMS, REMEDY AND SOLUTIONS

DRILLING 
oil gas drilling problems and solutions


Below general good practice steps to avoid general drilling problems encountered during drilling operations                                 

Inadvertent Side-tracking (in soft formation)

  • Wash through obstruction without rotating with the drilling Bottom Hole Assemply BHA.
  • Use bullnose (with centre jet plugged) on all hole opener and Underreamer runs.
  • When reaming a dogleg, lower the Drill String at a rate greater than the Penetration Rate RPM at which the section was drilled.

Gumbo (sticky shale)   

  • Use seawater native clay mud for sticky formation.
  • Control drill to at; 600 ft/hr.
  • Maintain circulation velocity at 200 ft/min.
  • If hole condition permits, drill the section with seawater and dump returns overboard.

Hole Cleaning

  • Maintain high annular velocity (+800 gpm for 12-1/4"€ WBM hole and +1000 gpm for 12-1/4" OBM hole sections).
  • Control drilling to at; 600 ft/hr.
  • Conduct frequent wiper trips.
  • Space out Stabilisers every 5 - 10 stands in the Drill String.
  • Pump in and out of hole - rotate if necessary.
  • Use low rheology fluid.

Borehole Instability (brittle shale)

  • Increase mud weight if possible.
  • After drilling each stand, wipe the full Drill Pipe stand at least twice with pumps on. If wiping a full stand causes directional problems, wipe with 2 singles at least twice.
  • Monitor drill cuttings for any sign of caving. If the cutting amount is suspicious, sweep hole with Hi-Vis pill and consider a wiper trip.
  • Use non-water based drilling fluids for brittle shale.

Lost Circulation (common in drilling carbonate formations)

  • Control drill so as not to overload the annulus with cutting.
  • Drill with maximum pump rate to clean the hole.
  • Ensure lost circulation material is adequately stocked on board
  • When sweeping hole with Hi-Vis pill, ensure the first pill is out of the hole prior to pumping another.

Swelling Shale                 

  • Minimise the openhole expose times.
  • Control the fluid loss from the drilling fluid to the formation.
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