NOV just completed a joint industry project with the aim to verify and demonstrate installation- and performance aspects of a full-scale Seabox subsea water treatment module in a realistic subsea environment. The Seabox module was installed close to Stavanger, Norway, at 220-meter water depth. Seawater was drawn through the module and a 540-meter-long pipe by use of a submerged pump. To verify the performance of the Seabox treated water, samples of the treated seawater were compared with raw seawater samples collected from the same seabed location.
The Seabox module has shown great results after a three-month duration of testing. Not only were the three parts of the Seabox module successfully installed, the treatment unit has been retrieved and the comparison samples show solids removal and disinfection capabilities beyond expectations. In that specific seafloor environment, the Seabox module removed on average 60% of all particles and 99.9% of all particles above 8.5µm. Tested according to oil industry practice, results demonstrate complete bacteria kill. There were also no SRBs or GRBs below detectable limits.
The Seabox subsea water treatment module showed a stable performance with 100% regularity throughout the test period, providing treated water with a stable solids removal and disinfection despite variations in the raw seawater quality. This verification of the performance of the Seabox module demonstrates the ability to serve a variety of duties for water injection – e.g. as pretreatment to filtration and membrane technology or as a standalone solution.
SOURCE: National Oilwell Varco