The O-lay offshore pipe lay technique has been discussed a lot lately. The reason for this because the O-lay method can be seen as one of the future pipe laying methods that is interesting for many area’s due to the relative low costs of operation, the possibility to lay from a few meters to several thousands of meters of depth and the high speed of laying.
The main difference between the new, state of the art, O-lay technique 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 and that after the pipeline has been coated according its specifications the pipeline will be transported as a whole, in a huge floating flat spiral to the location where it will be laid.
Although the technology is set up for laying pipe the reverse is possible as well. Retrieval of pipeline no longer in use is also possible with this technology. In some particular cases the pipeline can be reused for another oil or gas field again. Due to its length of the pipe being laid and that it is supplied in a whole to the lay barge the lay barge has a different role in the organization. It will only act as a pipe laying vehicle and storing, welding and inspection of the pipe finds place elsewhere.
Using the O-lay method pipe can be laid in very shallow as well very deep water due to the fact that the pipe is stored outside the lay barge. For deep water operation the possibility to prepare and construct the insulated “Pipe in Pipe” on an onshore location has several advantages compared to the preparation being done offshore and gives a lot of time saving during offshore operations.
With the O-lay method it is possible to use concrete weight coating around the pipe due to specific characteristics of concrete when using special additives. Several tests in laboratory and under real conditions have shown that the method described is feasible for pipelines of all diameters.