Abstract

The discharge of produced water accounts for the largest volume of waste associated with offshore oil and gas production operations. With the development and expansion of Canada's offshore oil and gas reserves, there is concern over the potential long-term impacts of produced water discharges in the ocean. Furthermore, recent evidence from other offshore oil fields in the world has suggested that production water discharges may impact the biota at greater distances from operational platforms than originally envisaged. To deal with this emerging issue, the present study focused on the development of tool for the assessment of environmental risks associated with produced water discharges based on the integration of ocean hydrodynamic and pollutant dispersion models. Specifically, a numerical approach, POM-RW, is developed based on an integration of the Princeton Ocean Model (POM) and a Random Walk (RW) simulation for pollutant transport. The POM is employed to simulate the ambient oceanographic conditions. It provides three-dimensional (3D) hydrodynamic input to a Random Walk model focused on the dispersion of toxic components within the produced water effluent stream at a regional spatial scale. Furthermore, a Monte Carlo approach, with the use of water quality standards, has been incorporated into the POM-RW to reflect uncertainties and to quantify the environmental risks associated with produced water discharges. Development and field validation of the predicted current field and pollutant concentrations were conducted in conjunction with a water quality and ecological monitoring program for an offshore facility located on the Grand Banks of Canada. Results demonstrated the utility of this model to support the effective management of produced water discharges in the future