The Construction and Importance of Offshore Pipeline
An offshore pipeline is a pipe laid on, or below, the seabed. They transport oil or gas to long distances. While pipelines transfer resources to the shore, an infield pipeline connects subsea wellheads, manifolds, and the platform to a development field.
Offshore pipeline construction projects require planning and considering many topographical factors, as well as offshore ecology and ecological loading. Large-scale projects particularly, are undertaken by international teams.
One of the first main offshore pipeline projects was Operation PLUTO. It was built amongst the Isle of Wight and France through World War II and stretched 48 km. This was an operation by oil companies, British engineers and the armed forces of Britain.
What is Used to Build Offshore Pipelines?
The key material used in the making of offshore pipelines is carbon steel, though other steels are put to use in the industry. The pipes are often supplied in single joints of 40 feet coated with concrete-weight epoxy for corrosion protection and allow their fitting on the seabed.
Recently, pipe-in-pipe constructions are used for providing thermal insulation to the inside of pipelines underwater.
The components of an Offshore Pipeline
An offshore gas pipeline system has compressor stations, city gate stations pipelines, and storage facilities. A compressor station is the hub of a pipeline system. It supplies energy for ensuring that gas flows through the pipeline at the precise pressure and flow rate.
There are three types of offshore pipeline, export, infield, and transportation pipelines.
Infield pipelines transport liquors, a mix of oil, water, and gas from the subsea wells to the process platform.
Procedure pipeline transporting only gas or only oil from the platform is recognized as a single-phase pipeline, while those that transfer a mix of the two are called multi-phase pipelines.
A transmission pipeline transports oil or gas from one shore to another. There are 3 types of pipes used in this procedure:
A SMLS has high flexibility and is fit for low temperate gases or liquids.
A HFW is thicker and has pressure welding, making it robust.
Similarly, a SAW has outstanding corrosion resistance, ideal for offshore pipeline systems.
The Construction Process of Offshore Pipeline
Before an offshore pipeline can be laid, there is a need for a seabed survey for obstacles and for ensuring there are no ecological issues with the site. Once the seabed is cleared, the pipes are joined, tested for faults and painted.
Numerous approaches can be put to use for installing pipes on the seabed. With a tow-in fitting, sections of pipeline are attached to markers and dragged out to sea. The buoys are then detached and the pipe sinks to the seabed.
With an S-Lay Fitting, large ships lower the welded pipes onto the seabed over a ‘stinger’ that juts out water in an s-shape. With a J-Lay fitting, the pipes are eased off the ship deck at a vertical angle, which forms a j-shape.
Each pipe weighs more than a few tonnes so they are ’re laid in trenches and in some locations, secured with residue from the seabed for further security.
Upon the installation of pipes on the seabed, a part is drawn onshore with a winch. The pipes are then linked to the onshore section and a tie-in is constructed.
With the whole pipeline in place, hydro testing is done, where pipe has water to check for defects. The pipeline condition is also monitored using with electronic devices.
Coming to a Conclusion
Due to the rising demand for oil and gas all over the world, the demand for offshore pipeline is on the rise, and it will reach USD 18,716 million by 2030.
