Most Read

Latest

Drilling 16 inch Section - Best Practices

  • Hold a pre-job safety meeting on BHA make up.

  • Make up 16” BHA as detailed in well specific programme.
  • Ensure a ported float is included in the string.
  • Circulate through the BHA and report weight in DDR.
    • Note: If a conventional motor steering assembly is to be used, ensure that the Directional Driller witnesses the correct toolface offset being entered into the MWD computer and a sign off form completed.

    • RIH with 16” BHA and tag stab-in shoe or cement.

  • Check pulse from MWD tool and commence displacing the mud whilst drilling out the shoe. Clean up the rat hole and condition mud throughout. Maintain flow rates below 2850 LPM to avoid excessive washout at the 20” shoe.
  • Utilise required mud weight from start of section (e.g. 1.5 sg) unless shallow salt well with expected loss zone.
  • Drill ahead.  The minimum flow rate to keep the hole clean is 2650 LPM.
  • Perform drill off tests to establish optimal RPM/WOB combination.
  • Increase flow rate to 3000 – 3400 LPM once the BHA is 15m below the 20” shoe provided losses are not observed.
  • On connections wipe the full stand once by pumping out and reaming back down. Wipe the bottom single once by pumping out and reaming back down. The driller must nominate a responsible person to control the mud pumps (e.g DD, Toolpusher, KPO Drilling Supervisor). This person will be responsible for shutting down the pumps quickly in the event of a pack-off.
  • Drill ahead to 13 3/8” casing point taking directional surveys approx. every three stands.
    • Directional Driller to monitor dynamic inclination readings and report to Drilling Supervisor if inclination trend will exceed 1.5 deg

  • Optimise flow rate (3500-4000lpm) and drilling parameters to maximise ROP and maintain inclination below 2 deg.

  • Monitor hole cleaning (SPP, PWD, drag, torque trends)
    • Driller to record up and down and rotating weights for each stand and report divergence from normal.

  • Monitor shakers for signs of cavings and pit levels for mud loss/gain. Mud logger to inform DSV immediately.

  • Don’t wait for survey after connection - if survey is corrupted continue drilling take survey after next connection.
  • Do not make wiper trips unless hole conditions - such as unmanageable increase in torque or drag - dictate. 
  • Drill to TD allow 5m rat hole.
  • Circulate bottoms up with full circulation (4000 LPM & 90-100 rpm until the shakers are clean.
  • Sweep hole with 5 m3 of Baralift pill if required.
  • Spot 10m3 of viscosified mud on bottom. This is to ensure that any fill is maintained in suspension, thus making it easier to wash the casing to bottom.
  • POOH, perform wiper trip if hole condition dictates.
  • The KPO Drilling Supervisor will be on the rig floor from start of the trip out of hole until the string is in cased hole.
  • Prior to starting the trip (during circulating bottoms up) check the following:
    • Record up-weight, down-weight, rotating weight and off bottom torque.
    •  Have a single of drill pipe available in the V door.
    • List of tight spots/intervals encountered during connections and previous trips.
    • BHA schematic with measurements between stabilisers and bit.

  • Upon encountering tight hole:

    • Go down and re-establish up-weight, down-weight, rotating weight and off bottom torque.
    • Apply overpull - starting with 20klbs - mark the pipe - go down - check the down drag - if negligible increase in down-drag then proceed by trying greater overpull.
    • Apply 30klbs overpull - mark the pipe - go down - check the down drag - if negligible increase in down-drag then proceed by trying greater overpull.
    • Apply 40klbs overpull - mark the pipe - go down - check the down drag - if negligible increase in down-drag then proceed by trying greater overpull.
    • Continue applying the above technique using 10klb increments up to a maximum of the weight of the BHA.
    • If on any overpull attempt, the down drag indicates that the pipe is becoming jammed, then make several attempts with less overpull.
    • If after several attempts there is no further progress (as seen from marks on the pipe) then go down, circulate clean - then try again.
    • If still no success to pass, then go down again and commence back-reaming procedures. Do not attempt to pump out of the hole as this may cause hydraulic compaction whereas rotation may disperse the blockage.  
  • If during a trip, the crew have to change tour, ensure that the Tool Pusher on tour is on the brake until a full handover is done between the drillers.
  • Back-reaming should be used as the last resort and with the same flow rate that was used during drilling.
  • Back-ream for 5m maximum, circulate cuttings clear of the BHA, then try to pull through the obstruction again using the above procedure - without pumps or rotation.
  • During back-reaming the driller must nominate a responsible person to control the mud pumps (e.g DD, Toolpusher, KPO Drilling Supervisor). This person will be responsible for shutting down the pumps quickly in the event of a pack-off.
  • In the event of a pack-off:- stop the pumps - go down with the pipe (maintaining rotation) - re-establish circulation - circulate clean.
  • Attempt to pull through obstruction again without pumps or rotation.
  • Repeat the above process - with patience. The objective is to POOH with the absolute minimum of back-reaming.
  • On the trip out of the hole, in casing, or during the running of the 13 3/8” casing, the mud pumps should be checked to ensure their reliability during the cement displacement.