The SIEM/HELIX vessels are well intervention vessels. The main work scope is to overhaul excisting wells or to do maintenance to wells. This is for instance when a well is clogged or there are other reasons or risks why a well is requires maintenance. Coiled tubing or wirelining are examples of well intervention, where chemicals are pumped into the well.
The SIEM/HELIX projects (SIEM-HELIX I and II) have a well intervention system, including a Multi Purpose Tower (MPT). Besides the MPT and Hydraulic Power Unit (HPU) Huisman delivered skidding systems and other transportation equipment, for example for risers.
Special about the SIEM/HELIX projects is the top tension: Most other Huisman delivered systems work with riser tensioners, but this vessel does not have riser tensioners. Instead, the whole riser string is held by the MPT. The MPT is equipped with Passive Heave Compensators to provide the passive heave compensation while connected to the well. The PHC system has a suppression valve to facilitate an Emergency Quick Disconnect (often also called an Emergency Disconnect Sequence).
At the end of the engineering phase I joined this project. My main work scope was to check up on all the diagrams and drawings, to check for inconsistencies. I also guided the production and commissioning phase of the projects. I was a contact person for all client, yard and class questions on the hydraulic system. This also includes a course for Helix employees to make them familiar with the system and procedures, and practice with them on a simulator to fulfill all procedures.