subsea
Post on 13-Apr-2016
2 Views
Preview:
DESCRIPTION
TRANSCRIPT
Challenges in Deepwater Subsea Installation Operations
Daniel Karunakaran, Subsea7
Who we are?A company dedicated to pure play SURF (Subsea, Umbilical,
Risers and Flow lines) engineering and construction in the global oil and gas sector.
Established in 2002 from the merger of Halliburton Subsea and DSND.
Listed on the Oslo Stock Exchange since August 2005.
Earned revenues of $2.19 billion in 2007.
Employ in excess of 5,000 people globally.
Backlog at 31 December 2007 $4.2 billion
Blind Faith
Engineering, procurement, fabrication, transportation & installation.
2 x Rigid flow lines (7km)
2 x Steel Catenary Risers
Seven Oceans’ first pipe lay job.
First deepwater Steel Catenary Riser for Subsea 7
Assets: Leith Spool base, Scotland
Water Depth:2200 m
Offshore Duration: Oct 2007
Saxi Batuque, AngolaEngineering design, procurement,
fabrication and installation
16 Flow lines (50km)
32 FLETs
14 heavy suction piles
Luanda Spool base
Challenging pipe and weld design
Assets: Luanda Spool base, Skandi Navica
Water Depth: 650-810m
Offshore Duration: Sept 2007 – Jan 2008
Ormen Lange Umbilical Installation
CHALLENGESEnvironmental
• Strong current• Uneven seabed
Umbilical Properties• Low submerged weight to diameter
ratio• Low bending stiffness
Operational limitations• Maximum ROV reach 250m for
touchdown monitoring
INSTALLATION CRITERIA
2.4m Design Hs 2.5m Design Hs1.5m Design Hs
High curvature
THE DEPRESSORMain Purpose is to stabilize the catenary
• Control the touchdown point
MAIN FUNCTIONS
• Weight down the umbilical• Reduce the layback for ROV monitoring• Reduce peak tension at touchdown• Straighten the curvature at touchdown• Fulfill tight lay tolerances
DESIGN CONCEPT
• Weight element with bellmouth in both ends
• Symmetric around CoG• Lifting points• Hang-off wire and umbilical common
over boarding point• Hinged door
Lifting point Centre of gravity
DESIGN PRINCIPLE
1. Acceptable umbilical curvature through depressor
2. Support various catenary configurations
3. Easy subsea removal4. Simple and non-sophisticated
PROJECT SPECIFIC DESIGN PRINCIPLE
1. Bellmouth radius2. Inner diameter3. Required length4. Weight and operational height
above seabed
INSTALLATION CRITERIA
1.5m Design Hs
With Depressor
3.4m Design Hs
OPERATING THE DEPRESSOR
Blind Faith Deepwater SCR Installation
Pipe lay Vessel – Seven Oceans
• Built – 2007• Length – 157 m• 400Te crane capacity• 3500Te Reel• 400Te tensioner capacity• Up to 16” diameter pipes
Blind Faith Development
• Operator: Chevron• Location: Mississippi Canyon - Block 696 and Block 650• Ultra-Deepwater – 2118 m• Steel Catenary Riser (SCR)• High specification welds• 40 Te PLET• Titanium Taper Stress Joints
Challenges
• Ultra deepwater – Top tension
• PLET Handling and initiation - 40 Te PLET
Challenges
• Attachment of strakes• Entire length of SCR• 5 m / min maximum
speed
Challenges
• Welding of Titanium taper stress joint• Fatigue is critical• Very limited time to
have high quality weld• Weld performed with no
cut-outs
Blind Faith Installation
Thank you
top related