Innovative and Cost Efficient Heat Traced Flowline with Improved Reliability

Abstract

The purpose of this publication is to present the development and qualification of an innovative heat traced flowline concept. Heat Tracing is a relevant solution for long tieback or when relying on a standard or hybrid production loop is not economical or not feasible. This concept is aimed at improving existing solutions and adapting the concept to J-laying installation methods thus allowing for the installation of larger diameters or accessing remote areas where a spooling base is not easily accessible. The developed concept is based on a conventional sliding pipe in pipe configuration that has been adapted and improved in order to include a heat tracing capability while optimizing laying rates. As commonly used in heat traced pipe in pipe concept (e.g. onshore applications), the electrical cables are wound around the inner pipe, covered with insulating material and enclosed in an outer pipe. Fiber optic cables are in general added for temperature monitoring purposes. In the case of this solution, several innovations aimed at improving the overall performance of the system have been implemented and tested. The proposed solution relies on a specific connector that allows for the simultaneous connection of all electrical wires and fiber optics in a single and quick operation. The concept of sliding pipe in pipe has also been improved, relying on packers and specific pipe end design that simplify the handling of quad joints and speed up offshore installation in J-lay. More specifically, the arrangement of the cables allows for an increased level of redundancy and reliability in the system while simplifying its operations. Finally, the pipe not being plastically deformed during installation fiber optics allow for the monitoring of both temperature and stress by the fiber optics. The paper will present: The main features of the concept;The qualification testing performed, including the connection system, fiber optics and packers;A specific focus on the reliability of the system;Details on the monitoring capabilities of the system which allows for improved operability. All tests have been performed at full scale and included pressure, temperature and deformation testing. They allowed for the demonstration that all components can be easily integrated within a conventional Pipe in Pipe design while significantly facilitating offshore operations. The performed tests allowed for validating and qualifying the design that is now ready for its first implementation.