Tie-backs to existing facilities are a long established method of expanding developments, as they often offer a cost-effective solution. For short length tie-backs located in regions that are remote and/or subject to severe weather conditions, however, the feasibility of installation can become a significant constraint. Factors such as high mobilisation cost of pipelay vessels and conditions that make pipeline towing impractical limit the potential design solutions. Defining these constraints early in the project is critical to successful execution. This extended abstract explores the challenges faced when developing such a tie-back by considering a case study of Origin Energy’s Geographe development, located in the Otway Basin. The location and harsh weather conditions constrained the viable installation options, which shaped the design. A flexible flowline was selected because it could be installed from a wider range of vessels and in a less limiting weather window. Subsea coolers are located at the wells for control of top of line (TOL) corrosion and to protect the flexible flowline from exposure to overly high temperatures. The cooler design brings its own challenges, requiring a two-stage process. First, modelling of the production fluid is used to determine the cooling requirements; then, CFD is used to design the cooler piping and structure to achieve this. A design with multiple, smaller structures was used to maximise the number of capable installation vessels. This extended abstract discusses the constraints that can occur, how the design must accommodate them, and the implications on execution of the project.
Terminal Airspace Capacity Evaluation Model under Weather Condition from Perspective of a Controller
