Innovative technology
The pipe laying technology as described here is very different from the common offshore technologies used at present. As compared to conventional methods of offshore pipe line installation, our method considerably reduces the length and costs of pipeline installation operations. For larger diameter pipes (up to 32") we expect to obtain a pipeline installation speed as high as 15 to 25 kilometer per day.
| spiral production & transport | Offshore pipeline installation and installation of PLET |
Our method can reach this high speed because the time consuming welding and testing procedures are no part of the actual pipeline installation process itself anymore.
Onshore welding and testing
The most significant difference between the new, state of the art, O-lay system and the existing systems is that the total length of the pipe is welded and tested onshore on a site that is near the waterfront. Depending on the local situation, series of “pipe segments” with a length of 50 to 1000 meter are produced and temporarily stored in the pipe yard untill they are transported onto the water.
Floating transport
The “pipe segments” are welded together in the final pipe line string and then transported onto the water. They will be kept afloat by means of floatation devices. A spiral will be formed with the floating pipe with a diameter that is sufficiently large to prevent the pipe from deforming in its plastic area. Normally the diameter of the floating circle is 500 times the pipe diameter (Example: A pipe with OD 20 inch will form a spiral of 250 meter diameter). The spiraled pipe can form a total length of more than 100 km pipeline. When the pipe spiral has reached its predetermined length, the entire spiral can be transported (towed by tugboats) to the installation location. Once the spiral arrives at the installation location, the spiral shall be unwound and with the aid of a special prepared vessel it will be lowered to the seabed. This method of pipe laying is interesting for very shallow water depths and depths where S-lay and J-lay methods are used.
Retrieving
Except of installing pipe with the O-lay method, it is also possible to retrieve pipe from the sea bottom and after inspection wind the pipe into a spiral. In this way it is possible to re-use the pipe on a different location. This will reduce the costs even further and is particulaarly applicable on very small oil or gas fields.
Tested
Several tests in laboratory and under real conditions have shown that the method is feasible for pipelines of all diameters. For pragmatic reasons we like to use the method for pipes with diameters not larger than 32".
