expert

ELF CONGO

KOMBI - LIKALALA

PROJECT

POSITIONING, SURVEY & ROV

YANGA FP BOW STRING INSTALLATION
TASKS LIST

1. METHOD STATEMENT
Bow string assembly

Bow string is built of a 2 inch wire, a 10 m, 1.5inch sling fitted onone end to the bow string with a 35T shackle.
The other end, the sling is equipped with Rov operated crossby shacklewhich end is prolongated by a nylon rope and Nokalon buoys
Flottability of the buoys is adjusted in order to balance weight ofthe shackle and one third of the sling’s one.

Monitoring of the operation
Support Vessel is positioned with DGPS in front of NW face of the YAFPplateform.
ROV is operated from Support Vessel and positioned with USBL and sonar
Monitoring of the relative position of the string lower end versusB1F node is performed by ROV (visual and Sonar).
Horizontal control of the position of the sling is performed by rotatingand rising/lowering the crane hook
Vertical control of the level of the string is done using the cranewinch.

Bow string Installation
86.5 m Bow string, 35 tons shackles, 10 m sling, 35 T ROV operatedshackle and buoy assembly are mobilised onboard M/V PEARL FISH, stringbeing reeled onto the tow main drum .
Rigger team with equipment is mobilised onboard YAFP plateform fromM/V PEARL FISH.
While vessel is position keeping 100 m in front of YAFP north-westface, complete line is lowered by the stern. Vessel slowly proceed towardthe Yanga platform crane and connect the crane hook to the upper end ofthe line using a small 1 ‘’sling.
Yanga crane heave the string and position it close to B1F jacket nodelocation facing ROW 2 under visual and sonar control of the ROV.
Vessel is positioned 50 to 100 m from the NW face of the YAFP.
ROV is launch from the Vessel and keep visual contact of the stringlower end.
After having adjusted the distance to the node and the level of thestring end, ROV passes the 10 m sling around B1F node and connect the 35TROV operated shackle to the lower end of the Bow string.
String is put under tension while ROV perform visual control of theplacement of the sling at the node level.
String is transferred from the hook to the 4 m plateform level andtemporarly secured to the boat landing SouthWest corner bollard.
Inspection of the bow string is performed by ROV

2. EQUIPMENT PREPARATION
The following parts are mobilised in PNR
Bow string is built of a 2 inch wire, a 1.5 inch sling fittedon one end to the bow string with a 35T shackle.
On the other end, the sling is equipped with Rov operated crossby shacklewhich end is prolongated by a nylon rope and Nokalon buoys
Flottability of the buoys is adjusted in order to balance the weightof the shackle and two third of the sling’s one.
ROV operated shackle is binded to the sling with tie raps and tapein order to be unable to move.3. ROV SUPPORT VESSEL MOBILISATION
Bow string is laid on the BOS Congo quai. Upper end is connected tothe tugger winch of the Support Vessel and reeled under tension.
Lower end of the string is secured on the stern of the vessel deckin order to be easily dropped into water. 35 T shackle is connected , 10m sling is connected, 35 t ROV modified shackle is connected and fittedto the sling other end in order to be unable to move. Nokalon type buoyassembly is connected by nylon rope.
Flottability of the sling/ shackle/ buoys is adjusted in order thebuoys to balance 2/3 of the sling weight and shackle weight.

4. YAFP PLATEFORM MOBILISATION

Upon arrival of the Pearl Fish on the area, rigger team is disembarkedto the YAQ plateform with all necessary rigging equipment and safety suits,etc…
Work permit is obtained from the Site Superintendant.
Inspection of the YAFP plateform is performed and breefing meetingwith Elf Congo PPM crane operator is held.
VHF handsets tuned on channel 69 are requested for the operation forRigger team leader, Crane operator, Vessel team leader, Vessel rigger teamleader, ROV team.
Lifting sling and 10 T shackle are connected to the crane hook.
Crane is positioned in front of B1 row, standing-by.
In the mean time, selected B1F (level ?74m) Node is made clear of anyrope and wire by ROV. No fishing net was observed during previous inspectionof the jacket.5. BOW STRING DEPLOYEMENT

Keep the Vessel in positioned using DGPS with stern facing Row 1 of YAPFjacket, 100 m away from the jacket centre position.

When everybody is ready and the vessel stabilised, operation is started.

Start lowering 2 m step by 2 m step, Rov operated 35 T shackle, 1.5 inch10 meter long sling , second 35 T shackle, first 10 m of the 2 inch bowstring from the vessel stern. Buoy assembly is dropped in water when needed.

Continue lowering Bow string by 5 m steps from the vessel stern.

When the upper end of the string is at the level of the stern of the deck,Yanga Crane is positioned in front of B1 row, (configuration 30m boom length,30 degree angle with horizontal, capacity of 2.35 MT).

Position Crane hook equipped with 1inch sling and 10 T shackle 5 m abovethe sea level perpendicularly to the jacket NW face.

Move Vessel with bow string hanging along her stern toward crane hook.

Connect upper end of the bow string to the hook

Disconnect vessel tugger line from the bow string.

Vessel is moving back to a position located 60 m from the jacket center.

Launch the ROV and proceed on request to the string lower end (buoys aregood sonar reflectors).

Start rising the bow string 5m by 5m up to the maximum position of thecrane hook.

ROV proceed to the buoys/ schackle assembly and monitor its position relativeto the jacket B1F Node.

Bow string is lowered and positionned 2 m from the node level using 2mstep by 2 m step method and ROV control between steps

When String is in position, ROV starts with sling installation around theB1F node.

6. SLING INSTALLATION AROUND JACKET NODE B1F
Sling installation Method "bottom to top" (see videoprintsbelow)

All position adjustments are performed by 1 m steps when close to the nodeposition.
Shackle supported by buoys is stopped at the bottom of the node level atthe ‘point of entry ‘ position.
ROV is positioned on the left side of the node directly under the nodelevel. Bow String is positioned 2 m from the jacket B1 leg.
ROV grabbing the jacket member with its 5 function arm, grab rope withbuoys with its 7 function arms and position the buoys inside the jacketunderneath B1F/C1F member of the node.
Buoys, nylon rope, shackle and sling slide inside the jacket around theB1F/C1F member of the node.
Bow string is re-positioned 2 m to A1 leg
ROV is repositioned on the right side of the Node, direcly above the B1F/A1Fmember.
ROV proceed inside the jacket , it grabes the nylon rope with buoys andpull it outside the jacket around the node.
One the sling end with rov operated shackle has been pulled out of thejacket.
- Shackle is firmly hold by ROV.
- Bow string is lowered in order to have the second end of the sling atthe level of the ROV with ROV operated shackle. Shackle is connected tothe other end of the sling.
- ROV perform visual inspection of the Node in order to acertain the slingis properly installed around the node.
- Bow string is rised 1meter step by 1 meter step using the crane whileROV monitor the behavior of ther sling around the node.
- When a slight tension is obtained, ROV start inspection of the stringrelative to the jacket up to 5 meters under the surface.
- Plateform riggers can start recovery and rigging of the bow string ontothe boat landing

7. BOW STRING RIGGING ON YAFP BOAT LANDING
Upon the end of the tensioning of the string using crane, rigger usingPlateform surfer to connect tirefor and chain to 2 inches string.
Release tension by lowering step by step the crane hook while retensioningthe bow string using tirfor from YAFP boat landing.
When all weight is transferred from hook to tirfor, release the crane hook,secure the string onto the souther bollard of the boat landing.
Demobilise jacket after acceptation of the rigging arrangement by ELF CONGORepresentative.

1     2
3     4
5     6
7      8
9       10
11       12