Appendix E Example Riser Running Procedure
E.1 MOVING STACK INTO RUNNING POSITION.
Safe handling of the BOP stack depends on the magnitude of vessel motions and the nature of the handling equipment on the particular rig. Some rigs are equipped with special transfer and guidance equipment to guide the BOP stack through the moonpool and the splash zone.
If the vessel motion characteristics permit, the stack can be moved into the running position. On most floating rigs, a set of spider beams is set across the moonpool either on the rig floor or cellar deck level. The stack is moved and positioned on top of the spider beams either by overhead trolleys or a bottom supporting cart or skid. The BOP stack components should be function tested and pressure tested as required using the BOP control system for functioning. This testing can be done either before or after the stack is positioned on the spider beams. After successful testing, the BOP stack is ready to be run.
- 2 RUNNING THE RISER AND BOP STACK. For a typical running procedure, the following steps include the most critical running operations.
- Prior to lifting the BOP off the spider beams, the BOP controls should be set in the running position and the riser connector should be verified to be latched. The controls should not be operated again until the stack is landed.
- The first riser section (usually two joints) above the BOP stack should be long enough to allow the BOP stack to be run into the water without stopping. When the BOP stack is in the water, its motions are damped.
- The riser couplings should be made up in accordance with manufacturer's recommended procedures. Correct make-up and preload of each coupling should be verified prior to its use as a tensile member. The make-up and break-out tools should be calibrated frequently and set to impart the proper preload to the riser coupling. (See RP2R for a further discussion of preload.)
- Ensure that the riser spider is properly engaged and supporting the riser before removing the handling tool. A gimballed spider should be considered when vessel pitch or roll motions cause large bending moments on the coupling.
- As riser joints are added to the string, the choke and kill lines and appropriate auxiliary lines should be pressure tested at regular intervals (usually every fifth joint). The choke and kill lines should be filled with water, control system supply lines should be filled with control fluid.
- The correct number and length of riser pup joints should be run so that, at mean sea level with the BOP stack latched to the wellhead, the outer barrel of the telescopic joint will be sufficiently above mid-stroke to accommodate stroke out caused by vessel offset.
- The collapsed and pinned telescopic joint should be made-up to the uppermost joint in the riser string and the outer barrel should be hung off in the spider. On most rigs, the BOP stack is landed with the telescopic joint collapsed and pinned, the additional string length provided by the temporary installation of an extra riser joint (referred to as a landing joint) above the telescopic joint. On some rigs, however, the diverter is made up at this point so that the telescopic joint can be unpinned and fully extended to prepare for landing the BOP stack. The shoe on the inner barrel and the pins joining the inner and outer barrels should each be designed to support the combined submerged weight of the BOP stack and riser as well as loads from dynamic effects. To avoid confusion, only the collapsed and pinned case will be further considered here.
- The riser, supported by the hook attached to the landing joint, should be lowered sufficiently to allow the riser tensioner lines to be attached to the outer barrel of the telescopic joint. The riser tensioners should be adjusted to reduce the hook load while the telescopic joint is supported on the hook. At this point, the BOP stack is in position to be landed.
- 3 LANDING THE STACK The BOP stack landing operation can be monitored using the underwater television system, divers, or a remote operated vehicle (ROV).
Caution should be exercised during the landing operation to avoid putting the riser in compression. Therefore, the BOP stack should be landed with the tensioners supporting more than the weight of the telescopic and riser joints, and the hook or heave compensator supporting the balance of the total weight.
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