Objective
Maintenance and repair of submarine pipelines gets harder and harder when depth increases.
For this reason SNAM, joint owner of the world's deepest pipeline (350 m), has developed (with other Companies of ENI Group) new techniques for automatic maintenance and repair of such pipelines.
The new system is called S. A. S. (Stazione Autonoma Sottomarina) and, at the present time, its construction is completed.
Although a series of deep water test was already scheduled, it is now considered that a full demonstration of the capability of the system is necessary, including the repair of a 20" sealine in deepwater.
The innovations and know-how expected from these trials consist in proving for the first time the feasibility of such operation at great dephts in complete automatic mode (all steps are computerized), and safety as the human presence is not required on the sea bottom.
The unexpected very poor bearing capacity (0,1 kg/cm2) and visibility of the seabed turned out to make harder testing the system. Furthermore, the malfunction of sensors compromised sommetimes the use of total automatic procedures (for example the acoustic navigation system). At any rate, concrete, polyethylene coating removal and pipe cutting were automatically carried out by the pipe preparation module, which, in addition recovered to the surface the cut pipe section - 12,25 m long simulating the damaged section. The base frame was also installed and clamped between the two prepared pipe ends; their distance and orientation were automatically measured and stored int the process computer 8on the surface). The first end connector was forged on the pipe end, problems encountered during extraction of the press caused damage to the lifting trolley. The seatrials were interrupted.
At present time a serie of modifications, ameliorations and studies are under way and a new deep sea trials campaign is foreseen for 1992.
2. A Main project phases
The project is developed in five main phases:
1) construction of connection systems
2) construction of a pipeline section (140 m)
3) transport of the pipeline offshore and laying at 350 m awater depth
4) repair of the pipeline on the sea bottom at 350 m
5) analysis of results and final report.
2. B Project phases
For each project phase the work schedule can be subdivided into the following groups of operations:
B1) construction of connection systems
. modifications and improvements to the connection system developed by Nuovo Pignone
. preliminary tests on reduced and full size scale
. construction of connection systems
B2) Preparation of the testing pipeline section
. setting up of onshore yard for transporting the pipeline offshore . purchase of 20" pipe lenghts, welding and installation of floats
B3) Transport of the pipeline offshore and laying 600 m depth
. mobilization and demobilization of two ocean-going tugs
. towing of the pipeline to the site ofinstallation and laying on the seabed
2. C) Repair of the pipeline
. Mobilization of a dinamically positioned ship and of a support vessel
. Modifications in the dinamically positioned ship for the installation on board of a part of the repair system
. Leasing of a complete R. O. V. system (SCORPIO class)
. Repair of the pipeline consisting in:
- removing any artificial overlays from the pipeline (to be defined in details later on)
- raising the pipeline from the seabed
- cutting and cleaning the two ends to be connected
- recovery the damaged pipe section by lifting it to the surface
- transporting the base frame into the seabed and measuring the spool to be connected
- installation of connectors on the pipe ends, sealing tests
- installation of the spool-piece, locking and sealing test of components
- recovery of modules from the seabed.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
20097 SAN DONATO MILANESE
Italy