PIPELINE ENGINEERING Multi-Diameter Pigging – Factors affecting the design and selection of pigging tools for multi-diameter lines Karl Dawson PPSA Aberdeen 19 th November 2008

Agenda Why Multi-Diameter Lines? Definitions Pig Selection Pig Design Provision of data for pig design Prototype Development and Validation Testing Case Study Summary Presentation End

Definitions Industry Accepted Definitions: Dual-diameter – Operates in 2 distinct diameters Multi-diameter – Operates in two or more diameters and may operate in a range diameters or sizes in between

Why Multi-Diameter Lines? Multi-Diameter lines are installed due to: Cost – Procurement – Installation – Associated features Standardisation – deepwater – Valves – Connectors Weight Space Necessity – Tie-in – Control Pressure losses Subsea Pigging Loop

Pig Selection Purpose of Pigging Operation: Dewatering Cleaning – debris removal Gauging Batching Inspection Camera Apply internal treatment Wax Removal

Pig Design Internal Diameters – Range of sizes Bend Radii – 5D, 3D or 1.5D Feature definition and configuration – Valve Gate Full bore ball Check Lengths of run Transitions Location of features – In relation to one another and specified diameters Factors Affecting Pig Design:

Pig Design Continued Factors Continued: Flow and Pressure Conditions Medium Expected Debris or Internal Line Condition Pig Trap – Dimensions – Configuration Interaction of Pig Characteristics to Negotiate Features Build up of Deposits Dual Diameter with Unbarred Tee

Provision of Data Interaction of line and pig features Influencing factors: Interaction Variation Combination All available data is of use in the process of design: ‘Every Little Helps’ Stick to the facts – never assume Wye and Bend Combination

Prototype Development and Validation Testing Why Test? Prove design Prove Functionality Gather Data Experience the unpredictable The overall objective to maximise tool effectiveness and to minimise risk Test Rig Example

Case Study 600m Water Depth: 8” x 10” Flooding, Cleaning and Dewatering Tool Operational Requirements: 8” Launcher and pipe work ID = mm Connector ID = mm 5D bend ID = mm Tapered transition = 1 in 6 10” Line ID = mm Buckle arrestor = mm Length fixed at 400 mm due to laydown head To be back loaded in to laydown head ID = mm Bi-directional capability Functional Requirements: Remove construction debris Flood line for hydrotest Dewater line

Pig Design: Mandrel Body Segmented Supports active in all diameters Diameter specific seals for each line section Symmetrical disc packs Transmitter housing Initial Design Case Study 600m Water Depth: 8” x 10” Flooding, Cleaning and Dewatering Tool

Test Rig Design: Case Study 600m Water Depth: 8” x 10” Flooding, Cleaning and Dewatering Tool

Final Proven Design Modifications made following trials: Extra discs fitted and radial grooves added to improve support in larger diameter Support flexibility improved in tapered transitions through reconfiguring the disc pack Quantity of sealing discs reduced to prevent discs clashing and loss of positive seal Pig has successfully been run in field operations Case Study 600m Water Depth: 8” x 10” Flooding, Cleaning and Dewatering Tool

Conclusions Involvement in the FEED stage is invaluable for both parties Free flow of information is key to an effective and suitable design solution Changes are ok, but the impact must be assessed Testing of the intended design is essential at reducing the risk involved in field operations With modern design capabilities and functional testing, multi- diameter pigging need not be a subject to be avoided, instead with careful consideration even the most arduous of diametrical variations may prove piggable

End Thank you kindly for listening Questions Welcome