Subsea pipe is a pipeline laid on the seabed to continuously transport oil, gas and water. Make a metaphor: offshore oil and gas facilities are all valuable “points”. Only by connecting “points” with “lines” such as oil and gas pipes, can a complete system be formed and the overall value of the production system be brought into play.
Submarine pipe: laid on the seabed, it is the main force of submarine oil and gas transmission
Expansion elbow: it is used to connect the submarine flat pipe and the riser. Due to the influence of sea water temperature difference, the steel pipe has the phenomenon of thermal expansion and cold contraction. The expansion elbow can compensate for the change of sea pipe length.
Riser: a vertical pipe on the sea floor, connecting the horizontal subsea pipe with the production facilities on the sea. The risers in shallow water are all steel pipes fixed on the pile legs of the platform. Deep water risers are usually free standing in the water, such as TTR, SCR, flexible riser, tower riser, etc.
Crossover: connecting Christmas tree and production manifold.
According to the difference of output (oil, gas, water) and output of oil field, the subsea pipe with corresponding diameter and structure shall be selected. Theoretically, the larger the output, the coarser the pipe diameter.
In order to prevent the hydrate formed by the deep water low temperature and high pressure from blocking the offshore pipe, it is necessary to use the thermal insulation pipe; while the offshore heavy oil needs to be transported after the platform is heated, so it is necessary to use the thermal oil transmission process and thermal insulation pipe structure.
Different materials of the sea pipe determine the production cost, erosion resistance, gravity requirements and welding performance of the sea pipe. At present, carbon steel is generally used, API 5L X56 and above.