How Pipelines Are Installed Under the Ocean - Network and Repair Underwater

Summary

This video provides an in-depth exploration of subsea pipelines, detailing their function in transporting oil and gas across oceans. It begins with the basics of wellheads, flowlines, and export pipelines, before delving into the complexities of the subsea network, including production manifolds, risers, and power supply systems like umbilicals. The video also covers installation methods, from seabed preparation to advanced techniques like S-lay, and concludes with the maintenance and repair processes. This comprehensive guide highlights the critical infrastructure and technology required to support subsea pipeline operations.

Takeaways

• 😀 A subsea pipeline is an underwater pipe used to transport oil or gas across long distances.
• 😀 The subsea pipeline network in Europe is extensive, with multiple types of pipelines serving different purposes.
• 😀 Flowlines transport oil or gas from the wellhead to processing facilities, while export pipelines carry processed oil or gas to onshore or offshore facilities.
• 😀 Transmission pipelines move oil or gas from coast to coast, mainly for trading purposes.
• 😀 Subsea systems involve several components such as subsea trees, jumpers, manifolds, and risers to manage oil flow.
• 😀 The subsea system requires power from umbilical cables, which contain high-voltage cables, electric cables, fiber optic cables, chemical, and hydraulic fluid lines.
• 😀 A subsea boosting pump is used when a reservoir has low energy to increase the oil flow rate.
• 😀 A subsea tieback allows new production sites to connect to existing platforms, saving costs on new infrastructure.
• 😀 Export pipelines often connect multiple offshore platforms to a main export pipeline, reducing individual construction costs.
• 😀 The installation of subsea pipelines involves seabed preparation, trenching, and laying pipes using methods like Tow-in, S-lay, and J-lay.
• 😀 In case of damage, subsea pipelines are repaired using subsea cranes, repair clamps, and bypass pipes to maintain oil flow during the repair process.

Q & A

What is a subsea pipeline and what is its primary function?

A subsea pipeline, also known as an offshore pipeline, is a length of pipe laid on or beneath the seabed. Its primary function is to transport oil or gas over long distances, connecting offshore oil and gas fields to onshore facilities or other offshore platforms.

What are the different types of pipelines used in a subsea system?

The subsea system uses various types of pipelines including flowlines (production pipelines), export pipelines, and transmission pipelines. Flowlines transport oil or gas from wellheads to processing facilities, export pipelines carry processed oil or gas to shore, and transmission pipelines move oil or gas over long distances for trading.

What role does the subsea tree play in subsea pipeline systems?

The subsea tree regulates pressure and controls the flow of oil or gas. It is installed at the wellhead to manage the extraction of oil and gas under high pressure from newly tapped reservoirs.

How do jumpers and production manifolds function in a subsea pipeline system?

Jumpers are short pipes that connect subsea trees to production manifolds, allowing oil or gas to flow from the subsea tree into the production manifold. The production manifold collects and directs fluid from multiple wells into one or more flowlines.

What is the difference between PLET and PLEM in subsea pipeline systems?

PLET (Pipeline End Termination) and PLEM (Pipeline End Manifold) are connection points in subsea systems. A PLET connects two pipelines, while a PLEM is capable of connecting and distributing the flow from more than two pipelines.

Why are subsea boosting pumps necessary in some subsea pipelines?

Subsea boosting pumps are used in cases where a reservoir has low energy or insufficient pressure. These pumps increase the flow rate of oil or gas to ensure efficient transportation through the pipelines.

What is the function of an umbilical in subsea pipeline systems?

An umbilical is a large cable that provides power to various subsea equipment. It contains high-voltage cables, electric cables, fiber optic cables, chemical fluid lines, and hydraulic fluid lines, supplying the necessary services to subsea equipment like manifolds and pumps.

What are subsea tiebacks, and why are they used?

Subsea tiebacks are processes that connect new production sites to existing platforms, reducing the cost of building new processing facilities. This helps expand production capacity by connecting multiple flowlines from different platforms.

How are subsea pipelines installed in deep-sea environments?

In deep-sea environments, pipelines are installed using remotely operated vehicles (ROVs) and pipelaying vessels. The seabed is surveyed, and the pipes are welded together on a pipelaying vessel before being lowered onto the seafloor. The process is continuous to avoid pipeline damage from stretching.

What are the main methods for laying subsea pipelines, and how do they differ?

The three main methods for laying subsea pipelines are Tow-in installation (used for short pipe sections), S-lay (used for long pipelines where the pipe is welded together and laid down in an 'S' shape), and J-lay (used for very steep areas). The S-lay method is demonstrated in the animation.