Ståle Johnsen

Determining produced water originating polycyclic aromatic hydrocarbons in North Sea waters : Comparison of sampling techniques

Abstract A field study was carried out in the Norwegian sector of the North Sea during May and June 1997. The purpose was to measure the concentration of produced water originating polycyclic aromatic hydrocarbons (PAH) in seawater and to compare different sampling techniques for use in future monitoring programs. Three methods were used for direct water sampling: (1) in situ large volume sampling of particulate and dissolved hydrocarbons onto filters and XAD resins, (2) solid phase extraction (SPE) using polystyrene-divinylbenzene disks, (3) whole bulk water sampling. In addition, sampling by semi-permeable membrane devices (SPMDs) and blue mussels (Mytilus edulis) was used to obtain a 4 weeks average of the concentration of the target compounds in seawater. The samples were processed and analysed by GC–MS for determination of PAH concentrations. The measured concentrations were generally found to be low, and in many cases below the limits of detection. The comparison of sampling techniques showed that blue mussels and SPMDs are suitable for measuring PAH in both near- and far-field seawater. In situ large volume water sampling was also suitable for a wide range of PAH concentrations, but this technique was limited by high break-through of the low-molecular weight compounds, such as naphthalenes. The small sampling volumes limited the SPE and whole water sampling techniques, resulting in potential detection limit problems. These grab-sampling techniques may, however, be suitable for monitoring in the near-field areas around the platforms.

Produced Water 2: Environmental Issues and Mitigation Technologies

This volume constitutes the proceedings of the Produced Water Seminar held in Trondheim, Norway, in September 1995. Hosted by Statoil Research and Development and IKU Petroleum Research, the seminar was an update of the 1992 seminar of the same title held in San Diego, California (Ray and Engelhardt, 1992). Produced water remains the largest volume waste stream from oil and gas production offshore. In the North and Norwegian Seas, produced water volumes are projected to increase significantly over the coming decades, as oil reservoirs near depletion. These releases are therefore the focus of continuing environmental concern. The purpose of this seminar was to provide a forum for scientists, legislators, and industrial and environmental representatives to share recent information and research results, and to encourage cooperative pursuit of solutions in the future. The success of the seminar, and the quality of this volume, are due in large part to the many authors from around the world who presented almost 50 posters and papers focused on environmental issues and mitigation technologies. In addition, we wish to acknowledge the contributions of the local and international organizing committees. Local Committee Asbj0fg 0verli and Heidi Torp, Statoil Egil Wanvik and Laila S. Olden, IKU Petroleum Research International Committee James P. Ray, Shell Chemical and Petroleum Products Companies Alexis E. Steen, American Petroleum Institute Theodor C. Sauer, Battelle Ocean Sciences Steven A. Flynn, British Petroleum Martin C. Th. Scholten, TNO Kjell Lohne, Statoil Ingvild Martinsen, Norwegian Pollution Control Authority.

Chemical and Ecotoxicological Characterisation of Oil–Water Systems

Abstract An ongoing chemical and ecotoxicological study of Water Accommodated Fraction of oils is presented and the preliminary findings are discussed. The study aims at obtaining improved and realistic data on potential environmental effects of various oils released and weathered at sea. Such data will be used for improving algorithms in present fate and effect models for damage assessment studies and “Net Environmental Benefit Analysis” of response alternatives in various spill scenarios. Preliminary results show that models used to assess effects in the water column will need to resolve the water soluble fraction of oils into more than one single bulk parameter to produce realistic estimates of effects.

The effect of sediment mimicking drill cuttings on deep water rhodoliths in a flow-through system: Experimental work and modeling

The impact of sediment coverage on two rhodolith-forming calcareous algae species collected at 100m water depth off the coast of Brazil was studied in an experimental flow-through system. Natural sediment mimicking drill cuttings with respect to size distribution was used. Sediment coverage and photosynthetic efficiency (maximum quantum yield of charge separation in photosystem II, ϕPSIImax) were measured as functions of light intensity, flow rate and added amount of sediment once a week for nine weeks. Statistical experimental design and multivariate data analysis provided statistically significant regression models which subsequently were used to establish exposure-response relationship for photosynthetic efficiency as function of sediment coverage. For example, at 70% sediment coverage the photosynthetic efficiency was reduced 50% after 1-2weeks of exposure, most likely due to reduced gas exchange. The exposure-response relationship can be used to establish threshold levels and impact categories for environmental monitoring.

An Intercomparison Between Field Measurements and Three Different Calculation Models for Estimates of Dilution Factors

Produced water releases have recently received increased attention due to its potential toxicity and its expected increase in the amounts on the Norwegian continental shelf for the years to come. Factors that govern the toxicity of the release when mixed into the recipient water becomes therefore essential. This paper deals with one such factor, namely the mixing rate of the release. When sufficiently mixed with the ambient water, the concentrations of the toxic components will fall below the:“No Effect Level” (NEC level), and harmful effects from the release are no longer expected. It is therefore of interest to determine how far off the release site (and how fast) this NEC level is surpassed for produced water releases.

Ecotoxicological Risk of Produced Water Discharged From Oil Production Platforms in the Statfjord and Gullfaks Field

The actual ecotoxicological risk of the discharge of produced water from an offshore oil or gas production platform is mainly based on the dilution processes around the platform. Risk analysis based on the chemical composition of the produced water may give some insight into the contribution of the individual components to the overall ecotoxicological risk, allowing specific measures to reduce the discharge of components associated with the highest risk.

Integrated environmental monitoring and multivariate data analysis—A case study

The present article describes integration of environmental monitoring and discharge data and interpretation using multivariate statistics, principal component analysis (PCA), and partial least squares (PLS) regression. The monitoring was carried out at the Peregrino oil field off the coast of Brazil. One sensor platform and 3 sediment traps were placed on the seabed. The sensors measured current speed and direction, turbidity, temperature, and conductivity. The sediment trap samples were used to determine suspended particulate matter that was characterized with respect to a number of chemical parameters (26 alkanes, 16 PAHs, N, C, calcium carbonate, and Ba). Data on discharges of drill cuttings and water-based drilling fluid were provided on a daily basis. The monitoring was carried out during 7 campaigns from June 2010 to October 2012, each lasting 2 to 3 months due to the capacity of the sediment traps. The data from the campaigns were preprocessed, combined, and interpreted using multivariate statistics. No systematic difference could be observed between campaigns or traps despite the fact that the first campaign was carried out before drilling, and 1 of 3 sediment traps was located in an area not expected to be influenced by the discharges. There was a strong covariation between suspended particulate matter and total N and organic C suggesting that the majority of the sediment samples had a natural and biogenic origin. Furthermore, the multivariate regression showed no correlation between discharges of drill cuttings and sediment trap or turbidity data taking current speed and direction into consideration. Because of this lack of correlation with discharges from the drilling location, a more detailed evaluation of chemical indicators providing information about origin was carried out in addition to numerical modeling of dispersion and deposition. The chemical indicators and the modeling of dispersion and deposition support the conclusions from the multivariate statistics. Integr Environ Assess Manag 2017;13:387-395.

Assessing the potential impact of water-based drill cuttings on deep-water calcareous red algae using species specific impact categories and measured oceanographic and discharge data.

The potential impact of drill cuttings on the two deep water calcareous red algae Mesophyllum engelhartii and Lithothamnion sp. from the Peregrino oil field was assessed. Dispersion modelling of drill cuttings was performed for a two year period using measured oceanographic and discharge data with 24 h resolution. The model was also used to assess the impact on the two algae species using four species specific impact categories: No, minor, medium and severe impact. The corresponding intervals for photosynthetic efficiency (ΦPSIImax) and sediment coverage were obtained from exposure-response relationship for photosynthetic efficiency as function of sediment coverage for the two algae species. The temporal resolution enabled more accurate model predictions as short-term changes in discharges and environmental conditions could be detected. The assessment shows that there is a patchy risk for severe impact on the calcareous algae stretching across the transitional zone and into the calcareous algae bed at Peregrino.

Application of Quantitative Risk Assessment in Produced Water Management – the Environmental Impact Factor (EIF)

The Dose-related Risk and Effect Assessment Model (DREAM) was developed through a JIP in the period 1997–2000 and was implemented for produced water (PW) management in the Norwegian sector of the North Sea as a part of the ‘Zero discharge work’, 2000–2005. The initial version of DREAM included two approaches to PW management, the Environmental Impact Factor (EIF) and a body burden related risk assessment model focusing on selected PW compounds. The EIF, addressed in the present chapter, has found broad application in the North Sea and has also been used in other offshore production areas by different companies. The produced water EIF is based on the risk assessment principles described in the EU Technical Guidance Document (TGD), comparing the Predicted Environmental Concentration (PEC) and the Predicted No Effect Concentration (PNEC) of PW compounds. The quantitative risk element in the model is represented by the water volume where PEC exceeds PNEC, including the combined risk of all major PW constituents, both naturally occurring compounds and industry-added chemicals. The EIF is used as a management tool, primarily to identify and perform cost–benefit analyses of PW mitigation measures and best available technology (BAT). The method enables the operator to identify the compounds posing the most significant environmental risk in PW, and further to rank different PW discharges with respect to environmental significance and risk. This chapter describes the EIF method and focuses on examples of application of the tool on specific offshore production fields. A description of how the EIF fits into Statoil’s environmental management system is also given, including the link between risk assessment, selection of BAT and field validation through environmental monitoring.