Today, there are more than 3 million miles of subsea pipeline located within the Earth’s oceans. These pipelines deliver trillions of cubic feet of natural gases and petroleum products each year. In recent years, the offshore oil and gas industry has experienced exponential growth due to the many commercial benefits of subsea pipelines. McDermott International, a fully-integrated provider of construction and engineering solutions for the oil and gas industry, has long been the provider of choice for pipelay and field development services. McDermott International’s Group Senior Vice President of Projects Samik Mukherjee hopes to inform the public on the importance of subsea pipelines in the oil and gas industry. Below, Samik Mukherjee will answer some of the public’s most asked questions regarding subsea pipelines.
What are Subsea Pipelines
Subsea pipelines, otherwise known as submarine pipelines, are any pipe system that has been installed below a waterline. Subsea pipelines most often refer to a pipeline used by industries to transport natural gas or crude oil underwater. Subsea pipelines can consist of various designs depending on the material being transported. This variety of pipelines are known for their complex installation processes due to highly turbulent sea conditions, which can cause bending stresses. While many subsea pipelines are installed a few meters below the water’s surface, many companies choose to place their pipelines on the seabed, which can require advanced engineering techniques to install.
How Subsea Pipelines are Installed
Subsea pipelines are placed on the seabed by large floating platforms known as pipelaying vessels. While these floating platforms can accommodate hundred of workers, multiple pipelaying vessels are required during the pipe laying process. After monitoring the seabed and located any obstructions, special barges supply pipes to the pipelayingvessels, which are then unloaded and welded. Before anticorrosion coating is applied to the pipe joints, they must be ultrasonically tested for any defects or breaks. Pipes that have passed the review stage are then placed on a conveyer and loaded onto a special boom called a stinger. The stinger slowly lowers the pipe onto the seabed at an angle, where it is attached to the pipeline.
How Subsea Pipelines are Repaired
Subsea pipelines are notorious for their complex and sometimes costly repair procedures. The repair procedure of subsea pipelines greatly depends on the pipeline’s depth, placement, and corrosion level. If a damaged pipeline has been installed at water depths above 300 m, professional divers will be able to repair the damaged pipeline using conventional repair methods. Diverless repairs occur on subsea pipelines located below 300 meters, or 985 ft, and are often carried out by mechanical connectors.