FEED work begins on Barossa subsea facilities

Barossa has entered the 'Define' (FEL 3) phase of the project where the development concept is defined and optimized and project planning matured. 

The goal of the Define phase is to complete any required optimization work and perform preliminary engineering and project execution planning in sufficient detail to support full project funding and approval. The team will accomplish this by progressing engineering and project plans to a level of detail necessary to generate the detailed basis of design, a detailed Project Execution Plan (“PEP”), a project control cost estimate, and an integrated project schedule to an AFE quality range of –10% to +15%. In addition, further risk analysis work is undertaken with mitigation plans developed for critical risks. Finalization of negotiations and contracting plans will occur during this phase. Long-lead items, if required, would also be ordered during this phase. This Front-End Engineering Design (FEED) is a key activity of the FEL-3 phase, which also includes tendering for execute contracts and confirming project execution plans, cost and schedule ranges.  

A FEED contract for the Subsea Umbilicals, Risers and Flowlines (SURF), Gas Export Pipeline (GEP) and associated systems design work was awarded to specialist engineering contractor, Intecsea, in Perth. Intecsea will mature the design to a level which is sufficient for contracts to be bid and prepared for award at project sanction.  

ConocoPhillips Barossa have a team of experienced subsea engineers who will guide Intecsea and also facilitate design at critical areas such as the FPSO and Bayu-Undan pipeline tie-in interfaces. This is one of the biggest challenges for FEL 3. Contracts and Procurement experts from ConocoPhillips Barossa will prepare and tender all of the subsea packages in preparation for award at FID.  

In addition to the Intecsea FEED contract, some elements of the Subsea Production System (are required to commence drilling of the wells, so these will be purchased as Long Lead Items.  

Scope 1: Subsea Production System (SPS)

The SPS controls delivery of gas from the wells to the FPSO and comprises:

  • Xmas trees which are connected to the top of the well to control the gas flow;
  • Production manifolds that direct gas and condensate into the flowlines;
  • Diverless connectors which join the subsea flowline network together; and
  • Production control system which commands the subsea valves and monitors instrumentation (such as pressure and temperature sensors on the Xmas Trees).

Scope 2: Subsea Umbilicals, Risers, and Flowlines (SURF)

The SURF scope includes all the equipment which connects the SPS and Gas Export Pipeline (GEP) to the FPSO. Control umbilicals supply power and communications to the Xmas Trees and production manifolds. Dynamic risers connect flowlines on the seabed to the turret on the FPSO. As the FPSO is continuously moving on the surface of the sea, the risers need to be able to absorb this movement and so are arranged in a flexible configuration maintained by distributed buoyancy.  

Scope 3: Gas Export Pipeline (GEP)

The FPSO will separate the natural gas and condensate extracted from the field, and the dry gas will be transported from the FPSO via a new 260km pipeline (GEP) to a tie-in point on the existing Bayu-Undan pipeline. A pipelay vessel which welds 12m long joints of pipe together will install the GEP by laying the pipe onto the seabed in a controlled manner. The installed pipeline is then connected to the risers at the FPSO on one end, and the Bayu-Undan pipeline at the other end using spools.