BOP - LOWERING PROCEDURE
Arockia Stalin
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Arockia Stalin
Director®| Project Management Professional | Offshore & Onshore Projects
- Pressure test of BOP is performed up to their rated working pressure.
- The BOP stack must be in perfect working order when lowered.
- Surface & BOP mounted accumulator bottles are to be pre-charged with Nitrogen to the calculated pressure.
- Prior lowering install guide lines in guide postes.
- Connect the riser, hanging from the hook to the BOP.
- Mount the riser angle beacon above the flex joint.
- Pressure test choke, kill booster & hydraulic lines to recommended test pressures.
- Carryout function test on both yellow pod & blue pod.
- Check all function are in block position.
- Switch hydraulic power unit to block position.
- Disconnect junction boxes on hose reels.
- Increase guideline tension to 8000 lbs.
- Check the tensioner's bottle pressure is at calculated value.
- Stand by bottles to be at max press.
- Hoist BOP stack assembly with the travelling block.
- Open spider beams & lower the BOP stack & continue lowering by adding riser joints.
- As each riser joint is added pressure test choke, kill & booster lines.
- Keep fitting pod hose clamps to the pod hoses & pod lines during BOP lowering.
- Connect telescopic joint (collapsed) to the last joint of riser.
- Lower telescopic joint and land it on spider below seal assembly.
- Add one dummy riser joint and slowly lower the assembly to the support ring.
- Actively lock down dogs (Rotating dogs) of support ring.
- Move slightly up and down to check that dogs are well in place.
- Unlatch blocking dogs.
- Slowly lower the assembly.
- Check riser tensioner pressure to carry all weight of string minus 20 T.
- Hoop up kill, choke, booster and hydraulic lines.
- Open the D.S compensator at 20 T.
- Continue BOP lowering monitoring the approach towards guide posts by ROV.
- Stop descent about 2-3 meters from guide posts according to heave conditions.
- Check hook load and lower stack carefully on wellhead while monitoring the ROV.
- Position the stack firmly and activate BOP wellhead connector to "lock".
- Perform pick up test by over pulling up to 20-25 T by means of compensator.
- Check all riser tensioner pressure.
- Open inner barrel & rest on spider and disconnect dummy riser.
- Make up diverter on inner barrel and install in rotary.
- Connect all hydraulic lines and break out diverter running tool.
- Decrease guide line tension to 4000 lbs.
- Carry out diverter operational check.