Presentation
Effectiveness of Subsea Mechanical Dispersion (SSMD) as a Function of Oil Properties
SessionSubsea Response Options
DescriptionMechanical devices can be used to disperse oil in response to a subsea oil and gas release. This response option is called subsea mechanical dispersion (SSMD) and the main objective is to reduce the oil droplet sizes from a subsea oil release, thereby influencing the fate and behaviour of the released oil in the marine environment. Smaller oil droplets sizes will decrease the amount of oil reaching the sea surface and increase oil biodegradation in the water column. Multiple options for SSMD have been tested and water jetting was early identified as an effective approach. This involves directing a water jet of ambient sea water towards the source of the released oil to enhance droplet breakup. Testing of water jetting both in small and medium-scale in the laboratory and in large-scale at Ohmsett has indicated that SSMD has a high potential to be used as an operational response method.
Earlier SSMD effectiveness testing has focused on a low viscosity, paraffinic oil. This paper describes testing of five different oil types spanning out a wide variation of relevant oil properties. All experiments were performed at a basin facility at SINTEF, Trondheim, Norway with oil release conditions relevant for a subsea release similar to Deep Water Horizon 2010 (low release velocity and multiple millimetre untreated oil droplets). Based on results of large-scale experiments, SSMD was performed with realistic water jetting rates (45-55% of released oil) and realistic ratio between water jetting nozzle- and oil release diameters. Subsea Dispersant Injection (SSDI) effectiveness was also measured in the same experiments with appropriate c dispersant injection techniques (insertion wand), dispersant dosage (1%) and with three commercial dispersant products.
Measured effectiveness (reduction in oil droplet sizes) for both SSDI and SSMD are generally high but varies significantly within the selection of oils. Averaged effectiveness for the two technologies over the five oil types are very similar and the small differences are probably not significant. Comparable effectiveness for SSMD and SSDI is consistent with earlier large-scale testing for SSDI (2015) and SSMD (2019) at Ohmsett.
Earlier SSMD effectiveness testing has focused on a low viscosity, paraffinic oil. This paper describes testing of five different oil types spanning out a wide variation of relevant oil properties. All experiments were performed at a basin facility at SINTEF, Trondheim, Norway with oil release conditions relevant for a subsea release similar to Deep Water Horizon 2010 (low release velocity and multiple millimetre untreated oil droplets). Based on results of large-scale experiments, SSMD was performed with realistic water jetting rates (45-55% of released oil) and realistic ratio between water jetting nozzle- and oil release diameters. Subsea Dispersant Injection (SSDI) effectiveness was also measured in the same experiments with appropriate c dispersant injection techniques (insertion wand), dispersant dosage (1%) and with three commercial dispersant products.
Measured effectiveness (reduction in oil droplet sizes) for both SSDI and SSMD are generally high but varies significantly within the selection of oils. Averaged effectiveness for the two technologies over the five oil types are very similar and the small differences are probably not significant. Comparable effectiveness for SSMD and SSDI is consistent with earlier large-scale testing for SSDI (2015) and SSMD (2019) at Ohmsett.
Event Type
Paper
TimeTuesday, May 14th4:30pm - 4:50pm CDT
Location278-280
Response