The Thinnest Jumper Successfully Installed in Place at a Depth of 1536 Meters Offshore

Date：2021-03-03

Recently, at a depth of 1536 meters in the Lingshui waters of the South China Sea, the 4.5-inch jumper of the East Manifold 3 was successfully installed. The jumper is the one of the thinnest pipe diameter and in the deepest water. For this reason, Lingshui 17-2 Gas Field Development Project has set a new record once again. Lifting by the ship, lowering steadily, seating precisely, locking & testing, and unhooking of rigging, all activities are done without stopping and only took 12 hours and 10 minutes. 

The jumper is a stronghold connecting the subsea pipelines, manifolds, wellheads and other facilities. The 4.5-inch jumper mainly works to inject ethylene glycol to prevent the formation of hydrates and guarantee the smooth operation of natural gas pipelines. There are 28 jumpers in Lingshui project. The completed one is the 8th jumper and also the most difficult one. With a horizontal length of 31.6m, a diameter of 114.3 mm, approximately as thick as an adult's wrist, and an installation depth of 1536m, it is laid generally in the shape of "M", and is the thinnest and deepest jumper in the Lingshui project. Although the South China Sea sees good conditions at this moment, it still trembles like a spring when being hoisted. Once the installation is started, it has reached the point of no return. That is to say, the jumper has to be accurately installed and placed because it can neither be recovered nor installed once again. Therefore, there is no room for error allowed in every step. 

With such strict requirements for installation as well as the influence of the uneven seabed during the installation of the manifold and PLET, the positioning direction of the jumper is made based on the inclination of the Hub port in the vertical direction of the two structures, so stricter requirements are posed on the seating of connectors on both ends of the jumper. The operation is carried out by two ROVs at the same time, and the connectors at both ends of the jumper are seated simultaneously. All operators are employees trained by CNOOC, operate precisely and show good teamwork for this "needle threading" operation in deep water. 

As the main operating vessel, Haiyang Shiyou 287 operates 24 hours a day during the Spring Festival, bringing a special Spring Festival with continuous record breaking. This has already been the 4th jumper installed in the Xinchou Year of the Ox (2021). 

Figure 1: Jumper hoisting 

Figure 2: ROV in operation