Presentation
Experiments to Study Weathering of Surface Oil Slicks Resulting from Sub Sea Dispersant Injection (SSDI) Operation
SessionSubsea Response Options
DescriptionSubsea dispersant injection (SSDI) has been established as an operative contingency method in many regions since it was introduced at a large-scale during the Deep Water Horizon oil spill in 2010 (DWH-2010). Offshore production of oil and gas in Norwegian waters is performed at shallower depths (100 – 400 meters) compared to 1500 meters depth during DWH-2010. In most oil spill scenarios in Norwegian waters a significant volume of the oil chemically dispersed subsea will surface due to the limited depth combined with high plume buoyancy from the uncompressed gas. In many scenarios with combined oil and gas releases, the plume will surface directly and most of the oil will be transported close to the surface regardless of oil droplet sizes due to the lift from the gas. The surface slicks formed will have reduced interfacial tension (IFT) due to the dispersant injected at the release point. It may be assumed that the low IFT will promote dispersion over emulsification for this surface oil, however the weathering behaviour of surface oil resulting from SSDI has not earlier been studied in detail, especially considering the effect of varying oil properties.
A laboratory study performed at SINTEF with five oil types spanning a wide range of oil properties concluded that residual surfactants from SSDI in surface slicks caused: (1) Reduced IFTs, (2) reduced water uptake, (3) reduced emulsion viscosity and (4) increased dispersion of surface oil (both natural and chemically enhanced). The reduced emulsification and enhanced dispersion would reduce the persistence of surface oil and may reduce the stranding of oil resulting from a subsea blowout with SSDI. The data from this study will be used to establish an algorithm describing how residual surfactants influence the weathering of a surface oil slick after an SSDI operation. This algorithm will be included in SINTEFs model system for Oil Spill and Response (OSCAR) to improve the description of surface oil slicks after SSDI treatments. This can be used to quantify a more realistic and higher SSDI effectiveness at shallower depths (< 400 m). This paper presents the laboratory work, highlights of the results and how the data can be used to improve modelling weathering of surface oil slicks after SSDI treatments.
A laboratory study performed at SINTEF with five oil types spanning a wide range of oil properties concluded that residual surfactants from SSDI in surface slicks caused: (1) Reduced IFTs, (2) reduced water uptake, (3) reduced emulsion viscosity and (4) increased dispersion of surface oil (both natural and chemically enhanced). The reduced emulsification and enhanced dispersion would reduce the persistence of surface oil and may reduce the stranding of oil resulting from a subsea blowout with SSDI. The data from this study will be used to establish an algorithm describing how residual surfactants influence the weathering of a surface oil slick after an SSDI operation. This algorithm will be included in SINTEFs model system for Oil Spill and Response (OSCAR) to improve the description of surface oil slicks after SSDI treatments. This can be used to quantify a more realistic and higher SSDI effectiveness at shallower depths (< 400 m). This paper presents the laboratory work, highlights of the results and how the data can be used to improve modelling weathering of surface oil slicks after SSDI treatments.
Event Type
Paper
TimeTuesday, May 14th3:50pm - 4:10pm CDT
Location278-280
Response