Submarine pipeline
A submarine pipeline (also known as marine, subsea or offshore pipeline) is a pipeline that is laid on the seabed or below it inside a trench. In some cases, the pipeline is mostly on-land but in places it crosses water expanses, such as small seas, straights and rivers. Submarine pipelines are used primarily to carry oil or gas, but transportation of water is also important. A distinction is sometimes made between a flowline and a pipeline. The former is an intrafield pipeline, in the sense that it is used to connect subsea wellheads, manifolds and the platform within a particular development field. The latter, sometimes referred to as an export pipeline, is used to bring the resource to shore. Sizeable pipeline construction projects need to take into account a large number of factors, such as the offshore ecology, geohazards and environmental loading – they are often undertaken by multidisciplinary, international teams.
Route selection
One of the earliest and most critical tasks in a submarine pipeline planning exercise is the route selection. This selection has to consider a variety of issues, some of a political nature, but most others dealing with geohazards, physical factors along the prospective route, and other uses of the seabed in the area considered. This task begins with a fact-finding exercise, which is a standard desk study that includes a survey of geological maps, bathymetry, fishing charts, aerial and satellite photography, as well as information from navigation authorities.