A Cost-Effective Subsea Rock Removal Tool for Deepwater application was developed for removal of subsea rock outcrops at 300-500m water depth in the Norwegian Fensfjorden. Subsea rock outcrops were restricting pull-in of the 36” oil export line from the Johan Sverdrup field to Mongstad through a 48” borehole, and a simple low-cost method for subsea rock removal without the use of explosives was developed for this purpose. The developed method reduces the need for traditional seabed intervention and hereby reduces the number of days involving Marine Installation vessels. This contribute to a positive impact on overall cost, HSE and Carbon Emission. The simplification is combining already existing subsea tools into one new tool for subsea solid rock removal. The application was successfully used in Fensfjorden for three different tasks October/November 2017 and March 2018. The method adds a new tool to seabed intervention, making route selection and pipeline installation in near shore areas with challenging seabed more flexible.
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