Experiments at Sea with Herders and In Situ Burning (HISB)

Abstract

ABSTRACT A series of experiments involving herders and ISB (designated HISB) were conducted at sea on 14th – 15th June 2016, near the Frigg Field in the North Sea. The primary objective of the experiments described in this paper was to demonstrate, at near-full scale, the use of herders followed by in situ burning (ISB) in open water conditions and validate the findings of an earlier field study of herders in conjunction with ISB. Two experimental releases of 6 m3 (approximately 40 barrels) and one of 4 m3 of Grane Blend crude oil were undertaken. The released oil spread out differently on the sea surface in each of the slicks due to slight variations in release conditions and prevailing wind conditions. Herder (ThickSlick 6535) was applied around two of the slicks by spraying from a small boat; a third slick was not herded before ignition. In the first test, approximately 80% of the total amount of thick oil was herded to form a coherent slick with an average oil layer thickness of approximately 3 mm to 5 mm. The second herded slick accounted for 40% of the amount of oil released and resulted in an average layer thickness of approximately 2 mm to 3 mm present as several discrete areas of thick oil. The average oil layer thickness in the non-herded slick was 2.5 mm to 3 mm (under very calm weather conditions) and this slick had also been broken up into several discrete areas of thick oil. Ignition with gelled gasoline igniters was carried out approximately one hour after oil release. All three slicks were successfully ignited. Approximately 3.4 m3 of the available oil in the first herded slick was consumed in three distinct burns, while the second herded slick consumed 0.8 m3 of oil in only one burn. The remaining test involving an unherded slick consumed approximately 1.2 m3 of oil in three burns.