The offshore oil and gas production in the Mediterranean Sea has considerably grown over the last 20 years, introducing a wide range of potential risk factors for the health of marine ecosystems. Crucial impacts may derive from discharges of produced formation water (PFW), a by-product of gas extraction, which to date represents approximately 80% of the waste and residual yield from natural gas production activities. The disposal of PFW may be carried out through the reinjection into the reservoir, the transport onshore or the discharge into sea water. We focused our attention on PFW discharged by submerged outfalls in the Adriatic Sea (a shallow Mediterranean subbasin characterised by an intense extraction and production activity). The effects of PFW discharge on the marine environment depend on the characteristics of the effluent as well as on the dispersion processes occurring in the receiving ambient fluid. In order to assess these potential environmental impacts we here apply a numerical dispersion model integrated with a monitoring plan developed for the Adriatic Sea. We simulated the initial mixing of PFW discharged from a selected offshore gas platform during the summer season, and used field data (samples of ambient sea water, current intensity and direction measurements, temperature and conductivity profiles) collected in the vicinity of the platforms from 2008 to 2010 during monitoring surveys. We evaluated several different discharge scenarios (in terms of environmental conditions and effluent characteristics) and three working hypotheses for the discharge operations. The results of this parametric study allowed us to identify a sort of “optimal discharge practices” for PFW in the Adriatic Sea which should promote the rapid dilution of the effluent and mitigate the impacts of the PFW on marine ecosystems.

Disposal of Produced Formation Water from offshore gas platforms in the Mediterranean Sea: a parametric study on discharge conditions aimed at mitigating risks for the marine environment

CIANELLI, DANIELA;ZAMBIANCHI, Enrico;
2013

Abstract

The offshore oil and gas production in the Mediterranean Sea has considerably grown over the last 20 years, introducing a wide range of potential risk factors for the health of marine ecosystems. Crucial impacts may derive from discharges of produced formation water (PFW), a by-product of gas extraction, which to date represents approximately 80% of the waste and residual yield from natural gas production activities. The disposal of PFW may be carried out through the reinjection into the reservoir, the transport onshore or the discharge into sea water. We focused our attention on PFW discharged by submerged outfalls in the Adriatic Sea (a shallow Mediterranean subbasin characterised by an intense extraction and production activity). The effects of PFW discharge on the marine environment depend on the characteristics of the effluent as well as on the dispersion processes occurring in the receiving ambient fluid. In order to assess these potential environmental impacts we here apply a numerical dispersion model integrated with a monitoring plan developed for the Adriatic Sea. We simulated the initial mixing of PFW discharged from a selected offshore gas platform during the summer season, and used field data (samples of ambient sea water, current intensity and direction measurements, temperature and conductivity profiles) collected in the vicinity of the platforms from 2008 to 2010 during monitoring surveys. We evaluated several different discharge scenarios (in terms of environmental conditions and effluent characteristics) and three working hypotheses for the discharge operations. The results of this parametric study allowed us to identify a sort of “optimal discharge practices” for PFW in the Adriatic Sea which should promote the rapid dilution of the effluent and mitigate the impacts of the PFW on marine ecosystems.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11367/30472
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