A lead is being taken by StatoilHydro in addressing the potentially harmful effects of near-shore effluent.
Having devised and led the environmental impact factor (EIF) approach, the group’s attention is now turning to near-shore effluent from land-based processing plants.
This is not only a concern today but will also become increasingly important as additional volumes of unprocessed wellstream are expected to be transported directly to land for primary processing.
StatoilHydro’s objectives are to quantify potential harm to coastal waters as the basis for introducing remedial measures, such as reducing the range and volume of chemicals used in oil and gas processing plants and introducing more environmentally acceptable substitutes.
In line with the EIF method, near-shore industrial effluent is first characterised by the ratio of the predicted concentration of potentially detrimental chemical components entering the sea to the tolerance level of marine ecosystems – the PEC/PNEC ratio.
But the parallel ends here.
- Near-shore circulation patterns and their dynamic responses to changing wave conditions, tides and seabed morphology are far more complex than in the open sea.
- The possibility that harmful components may accumulate in seabed sediments can no longer be ignored.
Dilution and eventual simulation models of sediment-water interaction must therefore reach new levels of hydrodynamic complexity.
StatoilHydro’s evolving methodology is currently being tested with the highly complex discharge from its Mongstad refinery north of Bergen, which consists of industrial effluent from storage tanks (ballast water) and hydrocarbon processing plants (process water).
The focus is largely on oil components and added process chemicals.
