Skarv Development project
Project Description
The Skarv development is located offshore Norway, 150 nautical miles northeast of Trondheim and has proven reserves in a number of fields (Skarv A, Skarv B&C, Tilje, Idun) of about 48 bcm rich gas and 17 mcm oil and condensate with an anticipated field life of 25 years. Water depth ranges between 300 - 450 m. BP Norge AS is the operator.
Skarv is the largest current ongoing field development offshore Norway.
The concept consists of a turret-moored Floating Production Storage and Offloading (FPSO) vessel located south of Skarv A/Tilje and east of Skarv B/C. The FPSO is considered to be a harsh water production facility. The FPSO will be used as a hub, processing the fluids produced from the subsea production and pumped back into injection wells. Phase one includes 15-16 subsea wells.
Export of oil and condensate will be by shuttle tanker and gas export will be via a dedicated 26” Gas Export Pipeline (GEP) (~ 80 km) to the Åsgard Transport System.
Figure Skarv Infield Flowlines concept
Scope of Work
The contract for the works has been awarded to Tideway – Boskalis Offshore JV.
The scope of work consists of the pre and post lay intervention works by means of rock dumping associated with the flowlines and the GEP.
Pre-lay rock dumping for this project is mainly required to level out rough sea bottom conditions, prior to installation of pipelines and subsea structures.
Post lay rock dumping is required for controlling forces on pipelines prior to flooding and during operation and for controlling forces on the flowlines.
Figure Infield lay-out
Main Activities:
The pre-lay scope for infield Umbilical, Risers and Flowlines (URF) consists of 13 rock supports for the 18 flowline PLET structures
The postlay scope for for infield intervention on the flowlines is:
• • 45 infill supports for free-span corrections (IN)
• • 39 wide infill rock carpets for free-span corrections (INC)
• • 52 covers for axial locking/anchoring (ARB)
• • 15 cover for upheaval buckling control (UC)
The postlay rock supports along the GEP are:
• • 5 Intermittent Rock Berms (IRD) for axial expansion control
• • 3 Crossing Uplift Covers (CRUC) on top of pre lay crossing supports (crossing of 8 lines)
• • 33 Uplift Covers (UC) to control pipeline buckling locations
• • 17 Infills (IN) in long free span locations
• • 3 Spool supports (SPOOL) for ERB, PLEM and Cross-over spools
Figure Example of PLET support; presurvey, design and as-built
Execution of the Works
Between August 2008 and July 2011. Work is performed in several campaigns
Equipment
The works are carried out with DP Fall Pipe Vessels Seahorse, Rollingstone and Sandpiper.
Quantities
Pre lay GEP approx 70,000 tonnes
Pre lay PLET supports approx 220,000 tonnes
Post lay GEP approx 170,000 tonnes
Post lay URF approx 600,000 tonnes
Figure Seahorse loading in Sandnessjoen at Aqua Rock quarry
