| Popis: |
As more complex oil reservoirs are discovered, innovative flow assurance solutions are required to make the development of new discoveries both technically and economically feasible. Indeed, depending on the size of the field, a long distance tie-back might be relevant to avoid the economic impact of a dedicated production platform. If the tie-back is too long, the water depth too deep and/or the fluid temperature at the wellhead too low, conventional flow assurance solutions might not be applicable. In addition, the size of the reservoir might not justify the installation of a service line or a second production line to generate a loop to allow preservation by mean of flushing the line with dead oil in order to avoid the formation of wax and or hydrates during shutdown. Active heating of the flowlines efficiently covers this gap. Among the available technologies, Heat Tracing appears as being an interesting technology as it features very high efficiency when compared to other solutions. To this date, this solution was limited to reel lay. This paper will present a design suitable for J-laying installation methods thus enabling the technology for larger diameters and remote locations, removing the need for a spool base. This new solution is based on a sliding pipe in pipe concept that has been adapted and improved in order to include a heat tracing capability while optimizing laying rates and offering enhanced monitoring capability including both temperature and stress surveillance. As in any other heat traced pipe in pipe concept, the electrical cables are spirally winded around the inner pipe and, covered with insulating material and enclosed in an outer pipe. Optical fibers are added in order to monitor stress and temperature. In the case of this technology, several innovations aiming at improving the concept have been implemented and tested. The concept mainly relies on a specific connector designed for the simultaneous connection of all electrical wires and fiber optic cables in a single and reliable 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. The performed qualification testing includes: Full scale fabrication; Testing of the connection system; Testing of the fiber optics; Testing of the packers to validate their holding capacity. All tests have been performed at full scale and included deformation and temperature testing. They allowed to demonstrate that all components can be easily integrated with a conventional Pipe in Pipe design while significantly facilitating offshore operations. The present paper will provide insight on the main features of the technology in addition to details on the performed qualification campaign. |
