Impacts of drilling mud and drill cuttings on sediment-water biogeochemical fluxes, oxygen regime and benthic communities

Produced water and drill cutting are the major sources of contaminants entering the sea from offshore oil and gas regular operation (Bakke et al., 2013). Offshore drilling activities discharge large amounts of drill cuttings (a mixture of reservoir rocks, drilling mud and added chemicals), and cause increased sedimentation around oil and gas installations. These discharges may affect benthic fauna not only through sedimentation (burial), but also through changed grain size and particle shape, toxic effects and oxygen depletion (Singsaas et al., 2008, Blanchard et al., 2014). The large overall discharge volumes, the complex content of partially hazardous chemicals, and the lack of knowledge on possible long term ecological impact has made produced water discharges the strongest target for concern and research in recent years. However, it is not able to measure at present the possibility of subtle, cumulative effect from the operational discharges. Modelling is required for the numerical estimates necessary to understand the consequences of the deposition from drilling and cutting. 

The overall goal of this proposal is to estimate the potential consequences of the drilling activity for ecosystem function and services through model-based analyzing the fate of priority substances in the affected areas.

We will use an O-N-P-S-C-Fe-Mn-Si Bottom RedOx Model, BROM (Yakushev, Protsenko, Bruggeman 2014) that considers the transformation of matter in the water column, bottom boundary layer and the upper sediment layer together aiming to elaborate the scenarios of potential biogeochemical and ecological effects of drilling activities. 

The received scenarios will be analyzed from point of view of satisfying to the Indicators for ecosystem assessments (Maes et al., 2013), the Water Framework Directive (WFD), the Norwegian management plan for the North Sea, the Barents sea and the Norwegian Sea, and OSPAR requirements.

Publications:

1. E.V.Yakushev, E.A.Protsenko, J.Bruggeman, R.G.J.Bellerby, S.V.Pakhomova, R.-M. Couture, S.Yakubov. Bottom RedOx Model (BROM, v.1.0): a coupled benthic-pelagic model for simulation of seasonal anoxia and its impact. Geoscientific Model Development Discussions, doi:10.5194/gmd-2015-239, in review, 2016.

2. S. Pakhomova, E. Yakushev. Modeling fate of Mn and Fe at the sediment/water interface in changing redox conditions. Goldschmidt 2015 conference. 16-21 August 2015, Prague, Czech Republic. Goldschmidt Conference Abstracts, р. 2382.

3. E. Protsenko, S. Pakhomova. Benthic fluxes in the Kara Sea and the Gulf of Ob. Goldschmidt 2015 conference. 16-21 August 2015, Prague, Czech Republic. Goldschmidt Conference Abstracts, р. 2545.

4. S. Pakhomova, E. Yakushev. Modeling of barium transformation in the seawater originated from produced water. XXI International scientific conference (Schools) on Marine Geology. 16-20 November 2015, Moscow, Russia. Proceedings. Volume IV, p. 73-77.

5. Pakhomova S. and Protsenko E. The truth is out there: measured, calculated and modelled benthic fluxes. European Geosciences Union General Assembly 2016, 17-22 April 2016, Vienna, Austria. EGU2016-14157.

6. Pakhomova S.V., Yakushev E.V. Modeling of metals transformation in the seawater originated from produced water. Arctic Frontiers 2016, Industry and Environment. 24 - 29 January 2016, Tromsø, Norway.