Subsea launch

 Pipeline Description:

36” tanker unloading line connecting a pipeline end manifold (PLEM) in the Atlantic Ocean of the south coast of Spain with a refinery near Huelva, Spain. The line extends over 9 km offshore from the PLEM to shore, then crosses a slim peninsula and then the port entrance of another 1.5 km under river before reaching the refinery territory this line is operated by two different operators. 

Why is it challenging?

Two new sections of the line were constructed by two different contractors: one for the offshore section to the peninsula (conventional offshore lay) and another for the section under the river (horizontal drilling) from the technical point of view of the operator, a bi-directional inspection could not be carried out. As one pipe-laying contractor concluded its part well ahead of the other, 3P’s tools had to be installed into the PLEM long before the tie-in of the two sections on the peninsula was expected. The laying barge had to move on, so the 3P tools had to be in starting position inside the PLEM before it was lowered to the seabed. Therefore, the 3P MFL tools had to cope with a waiting period of unknown duration. 

Target of the inspection:

A profile (gauge plate) run and an MFL baseline survey over the entire pipeline length was contracted to 3P Services. These were part of the acceptance process for the pipeline construction contractors. The inspection had to be done from sea to land.