Evaluation of Produced Water from Brazilian Offshore Platforms

Abstract

Chemistry and toxicity of produced water (PW) from offshore platforms operated by Petrobras in Brazil were investigated. Three studies -PW monitoring, detailed composition and temporal variability -were conducted during 1996, 2001 and 2006 Median chronic toxicity using Lytechinus variegatus showed a NOEC = 1.3%. These results for Brazilian PW are similar to those for the North Sea, Gulf of Mexico, Australia and other regions of the world. Dispersion plumes modelled using CORMIX and CHEMMAP predicted that PW can be diluted rapidly after discharge and that permissible levels for all chemical parameters in seawater cited in the Brazilian Resolution CONAMA 357/05 are attained within 500 m of the discharge point. Over 10 years (1998-2010) of monitoring in the vicinity of the Brazilian platforms did not show alterations in sea water quality, supporting the predictions of the dispersion plume modelling. Despite no observed alteration in seawater quality around oil and gas production platforms, the authors recognize the importance of continuous evaluation of the impact of PW discharges from a risk assessment perspective, and studies of bioaccumulation and the use of biomarkers, among other initiatives currently implemented by Petrobras in areas with large volumes of PW discharge. Up to and including 2011, Petrobras remains the major producer of oil and gas in Brazil and the total discharge of produced water by the country is essentially the volume that is discharged by offshore Petrobras operations. In 2005, the average total volume of PW discharged offshore on the Brazilian coast was 73 million m 3 /year, representing less than 3% PW discharged onto other oceans worldwide.

Produced water treatment by membranes: A review from a colloidal perspective

“…Benzene, toluene, ethylbenzene, xylene (BTEX), polycyclic aromatic hydrocarbons (PAH), total organic carbon (TOC), total petroleum hydrocarbon (TPH), total suspended solids (TSS) and salinity. Data reproduced from [9].…”

PAH assessment in the main Brazilian offshore oil and gas production area using semi-permeable membrane devices (SPMD) and transplanted bivalves

“…Within the Campos Basin, the modeled PW dispersion plumes had dilution factors from 100 to 700 within 200 m of the platform discharge points (Gabardo et al, 2011). However, despite some initiatives from bioaccumulation studies, no consistent results regarding the potential of bioaccumulation in tropical marine organisms have been reported.…”

Monitoring of polycyclic aromatic hydrocarbons in a produced water disposal area in the Potiguar Basin, Brazilian equatorial margin

“…At 2000 m distant, this dilution factor increased to 15. Therefore, this study demonstrates the high potential for dilution of the PW plume as modeled by Gabardo et al (2011), despite the subject location in a shallow coastal area. The PAH burdens in the transplanted bivalves at all sampling points were dominated by alkylated PAH compounds, particularly by phenanthrene and chrysene and its alkylated homologs (Fig.…”

“…Gabardo et al (2011) reported on a modeled PW dispersion plume for platforms located on the Ceará Basin, a scenario similar to the Potiguar Basin. For these platforms, the modeled PW dispersion plumes had dilution factors ranging from 700 to 900 within 500 m of the discharge point.…”