Subsea dispersants injection (SSDI), effectiveness of different dispersant injection techniques – An experimental approach

• Published in: Marine pollution bulletin Vol. 136; pp. 385 - 393
• Main Authors: Brandvik, Per Johan, Johansen, Øistein, Leirvik, Frode, Krause, Daniel F., Daling, Per S.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2018; Elsevier BV
• Subjects: Blowout; Dispersant; Dispersants; Dispersion; Droplet size; Droplets; Injection; Injection technique; Laboratory; Lipids - chemistry; Models, Theoretical; North Sea; Norway; Oil; Petroleum Pollution - analysis; Petroleum Pollution - prevention & control; Premixing; Subsea; Surface-Active Agents - chemistry; Surfactants; Turbulent flow; Turbulent jets; Water flooding; Water Pollutants, Chemical - analysis; Water Pollution - analysis; Water Pollution - prevention & control; Norway; North Sea; Dispersant; Droplet size; Laboratory; Blowout; Injection technique; Subsea
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2018.09.021

The main objective with this study has been to study injection techniques for subsea dispersant injection (SSDI) to recommend techniques relevant for both laboratory studies and operational response equipment. The most significant factor was the injection point of the dispersant in relation to the release of the oil. The dispersant should be injected immediately before or after the oil is released. Then the dispersant will mix into the oil and reduce IFT before the oil enters the turbulent zone where initial droplet formation occurs. All injection techniques tested gave significant reductions in oil droplet sizes. However, due to the rapid oil droplet formation in turbulent jets and possible formation of surfactant aggregates in the oil, premixing of dispersants should not be used for experimental studies of subsea dispersant injection. This could underestimate dispersant effectiveness and produce results that might not be representative for up-scaled field conditions. •Proper mixing of oil and dispersant is important during subsea dispersant injection (SSDI).•Effective mixing reduces IFT before the oil enters the turbulent zone where most of the droplet formation occur.•Smallest droplets are observed when dispersant is injected immediately before or after the release opening (± 6 D).•Premixing could lower effective concentration of surfactants in the oil due to formation of surfactant aggerates.•Premixing could underestimate SSDI effectiveness during laboratory effectiveness testing.