The heavy lift crane vessel ‘Saipem 7000’ has completed the installation of all ‘Ivar Aasen’ topside modules at the Ivar Aasen oil field in the Norwegian sector of the North Sea.For the lift, the crane vessel used its dual 7,000t cranes to lift the combined 15,000t modules from a Cosco heavy lift vessel onto a steel jacket attached to the seafloor.
The main part of the topside was built in Singapore and transported through the Suez Canal to the North Sea aboard the MV Xiang Rui Kou. The living quarters along with the flare boom and other modules were picked up along the way. Ivar Aasen field operator Detnorske says first oil is expected in December 2016.
Pipeline towing method is useful for bundled pipelines where several pipelines with different functions are packed together inside a large carrier pipe. The pipeline is constructed in a designed length onshore and towed into the sea.
Since there are many pipelines bundled together inside a big carrier pipe, it is imperative to get everything right prior to installation. Due to this reason, this installation technique allows the bundled pipeline to be welded, inspected and tested onshore prior to installation in order to minimize failure.
Reel lay method installs offshore pipeline by sending the pipeline from a reel mounted on a special pipeline installation vessel. Instead of connecting each joint of pipe line at an offshore location like other methods (S-lay and J-lay method), the pipeline is pre-assembled in a spool which is mounted on the deck of the reel barge. This method can lay pipe up to 16” diameter and water depth capacity for 16” pipeline is about 800 m (2,600 ft). This method cannot lay such a big size pipe because the big pipeline is not flexible enough to be rolled into a reel.
The reels can be installed either horizontal or vertical. Horizontal reel barges can do only S-lay installation; however, vertical reel barges can perform both J-lay and S-lay pipeline installation.
The reel lay method is considered to be the fastest laying method because the majority of welding and inspections are performed onshore in order to minimize time for installation. Once all pipe on the reel is laid, the barge either head back to shore of another reel or lift a new reel from a supply boat. This is dependent of each vessel.
Some of the images of reel lay barges are shown below;
Figure 1 – Vertical reel-lay barge in S-lay configuration
J-Lay pipeline installation method is frequently used in deep water pipeline installation. The curvature of pipe line is similar to J shape (Figure 1) while the subsea pipeline is being installed. J-Lay method can handle a full range of pipeline size and it is particularly suitable for deep water pipeline installation up to 2,000 m (6,560 ft). Furthermore, the J-Lay method can withstand higher underwater current and sea state than the S-Lay method.
The J-lay method puts less stress on the pipe line because the pipeline is installed in an almost vertical position. Whereas the S-lay method puts on more stress due to two curvatures at the sag bend and over-bend region. The pipeline is sent into water at a small angle reference to a vertical line and continues at a steep angle until a sag bend is formed.
Figure 1- J-Lay pipeline vessel
This works very well in deep water environment where distance from a vessel to a touchdown point is quite far because sag bend is not too much. If the short distance from a vessel to a touchdown point. Continue reading →
Wellhead installation is one of most fascinating topics and it is very difficult to visualize how this operation is performed. However, if you see this video, it will make the learning process so easy. This video demonstrate how to a stack wellhead from the beginning to the end of the process. Furthermore, we also add full video transcript which may help some learners to let more understanding.
Full VDO Transcript
There may be several strings of pipe in any given well. The number of the strings is determined by the number of zones being drilled through. These can include freshwater, saltwater and potential productions zones. Depicted here are 4 production or ‘pay zones’. Each zone would be cased off or isolated until it is to be produced.