Numerical Modelling of Oil Spill Transport in Tide-Dominated Estuaries: A Case Study of Humber Estuary, UK

Oil spills in estuaries are less studied and less understood than their oceanic counterparts. To address this gap, we present a detailed analysis of estuarine oil spill transport. We develop and analyse a range of simulations for the Humber Estuary, using a coupled hydrodynamic and oil spill model. The models were driven by river discharge at the river boundaries and tidal height data at the offshore boundary. Satisfactory model performance was obtained for both model calibration and validation. Some novel findings were made: (a) there is a statistically significant (p < 0.05) difference in the influence of hydrodynamic conditions (tidal range, stage and river discharge) on oil slick transport; and (b) because of seasonal variation in river discharge, winter slicks released at high water did not exhibit any upstream displacement over repeated tidal cycles, while summer slicks travelled upstream into the estuary over repeated tidal cycles. The implications of these findings for operational oil spill response are: (i) the need to take cognisance of time of oil release within a tidal cycle; and (ii) the need to understand how the interaction of river discharge and tidal range influences oil slick dynamics, as this will aid responders in assessing the likely oil trajectories.

Forecasting System for Predicting the Dynamics of Oil Spill in a Tide-Dominated Estuary

ABSTRACT Crude oil is predicted to become one of the most detrimental sources of anthropogenic pollution to estuaries. A comprehensive survey of oil spill literature reveals that oil spill transport in estuaries presents a gap in academic knowledge and literature. To address this gap, we present the first detailed analysis of estuarine oil spill dynamics. We develop and analyse a range of simulations for the Humber Estuary, using TELEMAC3D; a coupled hydrodynamic and oil spill models. The river boundary of the Humber Estuary is forced by discharge data, while the offshore boundary is driven by tidal height data, including estuarine water temperature and salinity. The calibrated model shows good agreement with measured data during the validation process. Results show that: (a) the time of oil release within a tidal cycle significantly influences oil slick transport; and (b) the tidal range significantly influences oil slick impacted area and overall distance travelled, as oil slick released under spring tide is approximately double the oil slick size under neap tides and travels on average 71% farther. This study emphasises the need to: a) understand how the interaction of river discharge and tidal range influences oil slick transport; and (b) be aware of the time of release within a tidal cycle, to efficiently deal with oil spills. Findings should be useful for future operational oil spill response and could be equally applicable to other tide-dominated estuaries.

The Crosby Warren Field, Block DL001, UK Onshore

The Crosby Warren Field is located onshore the UK, south of the Humber Estuary. It was discovered by RTZ Oil & Gas with the CW-1 (L46/12-3) well in 1986. The oil reservoir is Carboniferous, Namurian, Beacon Hill Flags sandstone, with gas found in Namurian sandstones of the Rough Rock, and the discovery well originally flowed waxy 40° API oil at rates of 45 bopd, which increased to nearly 700 bopd following fracture stimulation. The Beacon Hill Flags are a 10 m-thick group of laminated sandstones within a substantial gross thickness of sandstones, silts, muds and occasional thin claystones. The expected ultimate recovery for the field will be about 0.9 MMbbl of oil and 0.7 bcf of gas. Almost all of the oil and gas have already been recovered, and end of life for the field is expected to be in 2022.