Methane emission from shuttle tankers during standard operations on a oil platform during oil loading

Abstract

Results are shown from a study of methane emissions from offshore oil loading in the UK North Sea. This study is the first time that methane (CH₄) emissions associated with oil loading operations to shuttle tankers over the full loading cycle have been quantified, using measurements obtained from a research aircraft and an unmanned aerial vehicle (UAV), together with multiple modelling approaches to assess emissions from the complete tanker loading process. Periods of oil loading were associated with increases in CH₄ emissions in both datasets, ranging from 230 kg h⁻¹ (UAV) to 500 kg h⁻¹ (aircraft). When loading duration and frequency are taken into account, these emissions may contribute an additional 5-47% of CH₄ relative to the emissions reported by the Floating Production Storage and Offloading (FPSO) platform examined in this study. Methane emissions from oil and gas production, particularly in offshore environments, remain incompletely understood due to the large number of potential sources and the limited availability of observational data. Emissions associated with shuttle tanker loading from FPSO vessels are especially poorly characterised, with existing studies largely focused on non-methane volatile organic compounds (NMVOCs) rather than methane. Consequently, substantial uncertainty remains regarding how these emissions should be represented in emission inventories.