Offshore drilling effects in Brazilian SE marine

Environ Monit Assess (2017) 189:44 DOI 10.1007/s10661-016-5757-6

Offshore drilling effects in Brazilian SE marine sediments: a meta-analytical approach Marina Pereira Dore & Cássia Farias & Cláudia Hamacher

Received: 31 May 2016 / Accepted: 19 December 2016 # Springer International Publishing Switzerland 2016

Abstract The exploration and production of oil and gas reserves often result to drill cutting accumulations on the seafloor adjacent to drill locations. In this study, the detection of drilling influence on marine sediments was performed by meta-analytical comparison between data from pre- and post-drilling surveys undertaken in offshore Campos Basin, southeast of Brazil. Besides this overall appraisal on the geochemical variables, a multivariate assessment, considering only the post-drilling data, was performed. Among the variables, fines content, carbonates, total organic carbon, barium, chromium, copper, iron, manganese, nickel, lead, vanadium, zinc, and total petroleum hydrocarbons, only barium, copper, and hydrocarbons were related to drilling impacts. In relation to the point of discharge, relative elevated levels in the post-drilling campaigns were observed preferentially up to 500 m in the northeast and southwest directions, associated to the Brazil Current-predominant direction. Other distributed concentrations in the surroundings seem to

Electronic supplementary material The online version of this article (doi:10.1007/s10661-016-5757-6) contains supplementary material, which is available to authorized users. M. P. Dore (*) AECOM Brazil, Praia de Botafogo, 440, 24° andar, Rio de Janeiro, RJ 22250-040, Brazil e-mail: [email protected] M. P. Dore : C. Farias : C. Hamacher Laboratório de Geoquímica Orgânica Marinha (LaGOM), Faculdade de Oceanografia, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, 4° andar, Rio de Janeiro, RJ 20550-900, Brazil

indicate the dilution and dispersion of drilling waste promoted by meteoceanographic factors. Keywords Environmental monitoring . Well drilling . Metals . Hydrocarbons . Meta-analysis

Introduction Oil and gas exploration and production have intensified in Brazil and presented growth possibilities, even in the current scenario of economic recession (Brasil 2015; OPEC, Organization of the Petroleum Exporting Countries 2015). Drilling activity is among the initial steps for offshore production, whose major waste are the drill cuttings and drilling fluids or muds (IOGP, International Association of Oil and Gas Producers 2016). Drill cuttings are essentially crushed rocks as a product of the rotary bit as it penetrates into the rock layers, which end up carrying its chemical and mineral composition (IOGP, International Association of Oil and Gas Producers 2016; Thomas 2001). Drilling fluids used offshore are mixtures of fine-grained solids, inorganic salts, and organic compounds dissolved or dispersed in a primary fluid phase: fresh or salt water (water-based fluids—WBFs), or refined oil or synthetic materials (non-aqueous fluids—NAFs). Other than the primary fluid phase, barite (BaSO4) is also a major component of drilling fluids largely used as a weighting agent (Caenn et al. 2011; IOGP, International Association of Oil and Gas Producers 2016; Melton et al. 2000).

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After proper treatment on the rig, drilling fluid is recirculated down-hole and drill cuttings are commonly discharged offshore (IOGP, International Association of Oil and Gas Producers 2009; 2016). In Brazilian waters, the environmental agency allows the discharges of WBFs directly into the water, but NAFs can only be discharged when coating the cuttings. Since typically WBFs are used in the upper sections of wells and NAFs for drilling deeper and/or in more operationally difficult sections (e.g., deviated or horizontal wells), WBFs are usually discharged in the riserless phase close to the seafloor and NAF cuttings from the rig, near the sea surface (IOGP, International Association of Oil and Gas Producers 2016; Melton et al. 2000; Neff et al. 2000; Neff 2005). After discharged, drill cuttings dilute and disperse following the prevailing current direction. Larger particles, formed by around 90% of the mass of solids in the fluid (e.g., WBFs), fall rapidly to the seafloor, while the fine remaining solids form a plume close to the surface that settles at a slower pace and covers a wider area (IOGP, International Association of Oil and Gas Producers 2016; Neff 2005). NAF cuttings tend to form aggregates that contribute to the rapid deposition more restricted to the vicinity of the drilling unit in comparison with WBF cuttings (Brandsma 1996; IOGP, International Association of Oil and Gas Producers 2016). It is known worldwide that usual footprints of the drilling activities on marine sediments are metals and hydrocarbons, since drilling fluids contain higher concentrations of those components than the receiving sediments (Breuer et al. 2004; Neff 2008). However, most studies of the influence of drill cuttings consist of specific site data or revisions of previous publication, lacking on multi-site data integration using powerful statistics. Specifically in Brazil, there is a lack of publications about drilling impacts on marine sediment. Most of the existing studies are result of Environmental Monitoring of Offshore Drilling for Petroleum Exploration (MAPEM), a pioneer project developed in the Campos Basin, in which the principal goal was to study environmental effects promoted by one of the new-generation NAF cutting discharge (Toldo and Ayup Zouain 2009). In this context, the main objective of this paper is to integrate marine sediment geochemical data (fines content, carbonates, total organic carbon, Ba, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn, and total petroleum hydrocarbons), obtained in environmental monitoring projects of

offshore drilling executed in the Campos Basis – Brazil (wells drilled with WBFs and/or NAFs), using a meta-analytic approach, in order to distinguish which variables identify drilling impact.

Methods Study area Campos Basin is located in the southeast of Brazil between latitudes 20° 30′ S and 24° S. It covers approximately 100,000 km2 with more than 1600 wells drilled over four decades of oil and gas exploration. Campos Basin houses over 90% of Brazilian reserves and is responsible for around 60% of national oil and gas production through 48 fields (ANP, Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (2016); Viana et al. 1998; Winter et al. 2007). The study area is bordered by the Brazil Current (BC) up to around 400 m depth, which flows towards S-SW and comprehends the water masses Tropical Water and South Atlantic Central Water. Below the BC (~ 500–1200-m depth), there occurs an opposite flux to N-NE, the Brazil Intermediate Counter-Current, which transports the Antarctic Intermediate Water (Rocha et al. 2014; Silveira et al. 2000; Silveira et al. 2004). The continental shelf is delimited by the isobathymetrics of 10 and 150 m, presenting a maximum width of 120 km in the south area with general declivity of 0 to 0.5° (Figueiredo et al. 2015). The continental slope is comprehended between the isobathymetrycs of 110–200 to 1200– 2300 m with declivity that varies from 0 to 25° (Almeida and Kowsmann 2011). According to Figueiredo et al. (2015), in Campos Basin, there is a predominance of terrigenous lithoclastic sediment (tenfold than natural sediments, not considered to be toxic), As, Fe, and Ni (all potentially toxic) (Altin et al. 2008; Neff et al. 2000; Neff 2005, 2008). Among these metals, Ba and Cu formed a close group in the presented PCA, revealing that their origins are potentially the same. It is more likely that the source clustered those metals than possible environmental transformations on sediment, since their most stable forms vary according to redox conditions—Ba is more stable as sulfate (oxic condition) and Cu is more stable as sulfide (anoxic condition) (Neff 2008). Barium presented higher median concentration in the post-drilling campaign than background levels, with concentrations variations considered significant by both U test and meta-analysis. Copper concentrations were also significant between the pre- and post-drilling surveys (U test), with increased concentrations in the post (Hedges’ g). Zinc values similarly presented positive summary effect in the meta-analysis and significant difference between the campaigns (U test). However, Zn remained in the PCA in another group formed with Ni and Pb, that seems to be in transition to the other clustered group of Cr, Fe, V, and Mn, suggesting the absence of relation with Ba and Cu (Fig. 2 and Table 2). Regarding meta-analysis results, Hedges and Hedberg (2007) consider effect sizes around 0.20 of policy interest when based on academic measurements (in other words, trustful and with scientific rigor). Metaanalytical summary effects for Ba and Cu fit this criterion, especially Ba (0.69 and 0.10, respectively)


(Table 2). The forest plots deliver substantial context for the analysis, since they highlight that effect sizes are mostly coherent for each study. An effect size to the left of center, where Hedges’ g is equal to zero (null effect), indicates that the variable concentration was higher on the pre-drilling survey than that in the post, revealing a decreasing pattern looking at the post-drilling campaign. In contrast, an effect size to the right indicates increased concentrations in the campaign after the discharges occurred in comparison with the background levels (Fig. 4) (Borenstein et al. 2009). Ba and Cu concentrations on the post-drilling campaigns tend to be more elevated when closer to the point of discharge, as trend suggested by the opposite position of the distance vector in the PCA, which in turn is related to the direction vector (Fig. 3). This hypothesis is reinforced by the case projections that show a close relation to distances until 500 m and directions NE-SW. Those directions are associated to the Brazil Current, that flows preferentially towards SW in the top layer, while during winter and with cold front entrances, the wind tends to blow from SW to NE, consequently, inverting the regional circulation (Rossi-Wongtschowski and Madureira 2006; Stramma and England 1999). The observed records in other directions point out the importance of drilling waste dilution and dispersion (IOGP, International Association of Oil and Gas Producers 2012) and also motion of bottom currents, probably associated to bottom Ekman layer, which is highly important in promoting fluid transportation in association with friction in the seabed (Madron and Weatherly 1994). Breuer et al. (2004) points that metal’s high concentrations on cutting piles in the North Sea are a combination of accumulation and transport from natural sediment, discharged cuttings and fluids (barite and chemicals), drilling units (e.g., paint chips or corrosion), and aeolian input. In the present study, the elevated levels of Ba and Cu in Campos Basin seem to be more related to the drilling influence. Hydrocarbons During drilling operations, the main sources of hydrocarbons to the marine environment are drilling fluids and drill cuttings. Adhered NAFs to cuttings constitute the primary source of these hydrocarbons, since its base composition is essentially organic (such as low-toxicity mineral oil, refined mineral oil, and synthetic fluids— esters, paraffins, and olefins), whereas WBFs may


contain organic additives (e.g., organic polymers as viscosifiers and organic fatty acids as emulsifiers). Another petroleum hydrocarbon source is the geologic formation, which may contain traces even after treatment carried out in the drilling unit (Breuer et al. 2004; IOGP, International Association of Oil and Gas Producers 2016; Neff 2005; Peralba et al. 2010). In this study, TPH was grouped with Ba and Cu in the multivariate analysis (Fig. 2). Similarly to those grouped metals, the same origin is the most probable explanation for the cluster observed. The fate of hydrocarbons on drill cutting piles is determined by local biogeochemical cycles, which in influenced by variation of oxic and anoxic environments. Under anaerobic conditions, hydrocarbon degradation is impaired (Breuer et al. 2004), while the group formed encompasses stable forms in different redox conditions. Like Ba, TPH presented significant higher concentrations on the post-drilling surveys in comparison to that on the pre-drilling (U test), with reinforcement on the meta-analytical assessment. Although the summary effect is not significant, most studies presented positive effects with a few significant ones, as can be noticed in the forest plot (Fig. 4 and Table 2). According to the Hedges and Hedberg (2007) criteria, TPH summary effect is around 0.20 meaning that it is also relevant (0.19). The TPH response in the multivariate analysis suggested the same pattern described for Ba and Cu, that is, a tendency of decreasing concentration with the distance of the discharge point, with higher levels preferentially up to 500 m and NE/SW directions. The main difference between petrogenic hydrocarbons and biogenic is that petroleum has a more complex mixture of hydrocarbons (Kennish 1992; Simoneit 1993). In the assessed monitoring reports, when TPH was observed, it was also quantified the unresolved complex mixture (UCM) beyond the resolved fraction. Between those fractions, the UCM was predominant, which suggests a petrogenic source, probably either from the drilling fluids and/or from geological formations (Bianchi and Canuel 2011; Peters et al. 2005). Another point is that, in two post-drilling surveys nalkanes from n-C11 to n-C14 were quantified from 0.17 to 1016.64 mg.kg−1. The n-alkanes of fossil origin possesses varied composition depending on the type of source (crude oil, derivatives, etc.), but petroleum usually has n-alkanes between 1 and 40 carbon atoms without odd or even chain predominance (Simoneit 1993). Although it is not possible to provide a direct

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conclusion, taking as an example the n-paraffin fluid used in Brazilian waters described by Peralba et al. (2010), and considering chains between n-C13 to nC18, the verified distribution could be an indication of a fluid or geological formation contribution. In addition, in the North Sea, hydrocarbons related to drilling operations are predominantly alkanes from n-C15 to n-C22 and n-C10 to n-C27 (Breuer et al. 2004).

Summary and conclusions From the evaluation of the thirteen variables monitored in the pre- and post-drilling oceanographic campaigns in drilling sites, it was found that Ba, Cu, and TPH have been functioning as tracers of well drilling activities in Campos Basin. The influence of drilling process on these variables, represented by relative elevated levels in marine sediments after drilling waste discharges, was observed predominantly within 500 m and in the northeast and southwest directions. Relative higher concentrations were also found in other distances and directions, demonstrating the importance of meteoceanographic factors promoting the dispersion of contaminants. The other variables—fines content, carbonates, TOC, Cr, Fe, Mn, Ni, Pb, V, and Zn—showed no conclusive pattern that could be associated to the influence of drilling activities. Acknowledgments The authors would like to thank Anadarko, Statoil, and IBAMA (Brazilian Environmental Agency) for the data provided which support this work. The authors also thank the reviewers for valuable comments. The contents and conclusions are author’s achievement and do not necessarily reflect the companies’ views and practices.

References Almeida, A.G., & Kowsmann, R.O. (2011). Caracterização geomorfológica do fundo marinho do talude continental da B a c i a d e C a m p o s . h t t p : / / w w w. a b e q u a . o r g . br/trabalhos/ALMEIDA_2011_ABEQUA.pdf. Accessed 10 May 2016. Altin, D., Frost, T. K., & Nilssen, I. (2008). Approaches for deriving of environmental quality criteria for substances applied in risk assessment of discharges from offshore drilling operations. Integrated Environmental Assessment and Management, 4(2), 204–214. Anadarko. (2011). Relatório Final das campanhas de pré e pósperfuração do poço 1- APL- 4D-RJS. Rio de Janeiro: Anadarko.

44

Page 10 of 11

ANP (Agência Nacional do Petróleo, Gás Natural e Biocombustíveis. (2016). Boletim da Produção de Petróleo e Gás Natural – número 67. Rio de Janeiro: ANP. Bianchi, T. S., & Canuel, E. A. (2011). Chemical biomarkers in aquatic ecosystems. New Jersey: Princeton University Press. Borenstein, M., Hedges, L. V., Higgins, J. P. T., & Rothstein, H. R. (2009). Introduction to meta-analysis. United Kingdom: John Wiley & Sons. BP. (2012). Campanha de Caracterização Ambiental (Projeto de Monitoramento Ambiental - Campo de Polvo - Malhas de Produção e Perfuração), Bacia de Campos - 6ª Campanha de Monitoramento (2012). Rio de Janeiro: BP. Brandsma, M. G. (1996). Computer simulations of oil-based mud cuttings discharges in the North Sea. In E&P Forum (Ed.), The physical and biological effects of processed oily drill cuttings (summary report) (pp. 25–40). London: E&P Forum. Brasil. (2015). Ministério do Planejamento. Brasil bate recorde na produção de petróleo e gás. http://www.pac.gov.br/noticia/1 c3eda4f. Accessed 3 january 2016. Breuer, E., Stevenson, A. G., Howe, J. A., Carroll, J., & Shimmield, G. B. (2004). Drill cutting accumulations in the Northern and Central North Sea: a review of environmental interactions and chemical fate. Marine Pollution Bulletin, 48, 12–25. Caenn, R., Darley, H. C. H., & Gray, G. R. (2011). Composition and properties of drilling and completion fluids. Waltham and Oxford: Elsevier. Campos, V.B. (2014). Monitoramento ambiental das atividades de perfuração exploratória através da análise geoquímica de sedimentos oceânicos da Bacia de Campos. Dissertation (Master). Niterói: Universidade Federal Fluminense. Devon. (2011). Campanha de Caracterização Ambiental (Projeto de Monitoramento Ambiental - Campo de Polvo -Malha de Produção e Perfuração), Bacia de Campos – 5ª Campanha de Monitoramento (2011). Rio de Janeiro: Devon. Duval, S., & Tweedie, R. (2000a). A nonparametric ‘trim and fill’ method of accounting for publication bias in meta-analysis. Journal of the American Statistical Association, 95, 89–98. Duval, S., & Tweedie, R. (2000b). Trim and fill: a simple funnelplot-based method of testing and adjusting for publication bias in meta-analysis. Biometrics, 56, 455–463. Figueiredo, A. G., Pacheco, C. E. P., Vasconcelos, S. C., & Silva, F. T. (2015). Geomorfologia e sedimentologia da plataforma continental. Rio de Janeiro: Elsevier/Habitats. Hedges, L., & Hedberg, E. C. (2007). Intraclass correlation values for planning group-randomized trials in education. Educational Evaluation and Policy Analysis, 29, 60–87. IOGP (International Association of Oil & Gas Producers). (2009). Drilling fluids and health risk management. A guide for drilling personnel, managers and health professionals in the oil and gas industry. Report No. 396. IOGP. IOGP (International Association of Oil & Gas Producers). (2012). Offshore environmental monitoring for the oil & gas industry. Report No. 457. IOGP. IOGP (International Association of Oil & Gas Producers). (2016). Environmental fates and effects of ocean discharge of drill cuttings and associated drilling fluids from offshore oil and gas operations. Report No. 543. IOGP. Kennish, M. J. (1992). Ecology of estuaries: antropogenic effects. EUA: CRC Press.

Environ Monit Assess (2017) 189:44 Madron, D., & Weatherly, G. (1994). Circulation, transport and bottom boundary layers of the deep currents in the Brazil Basin. Journal of Marine Research, 52(4), 583–638. Melton, H.R., Smith, J.P., Martin, C.R., Nedwed, T.J., Mairs, H.L., & Raught, D.L. (2000). Offshore discharge of drilling fluids and cuttings – a scientific perspective on public policy. In: Rio Oil & Gas Expo and Conference (pp. 1–13). Rio de Janeiro: IBP. Neff, J. M. (2005). Composition, environmental fates, and biological effect of water based drilling muds and cuttings discharged to the marine environment: a synthesis and annotated bibliography. Petroleum Environmental Research Forum (PERF) and American Petroleum Institute (API): Duxbury. Neff, J. M. (2008). Estimation of bioavailability of metals from drilling mud barite. Integrated Environmental Assessment and Management, 4(2), 184–193. Neff, J. M., Mckelvie, S., & Ayers, R. C. (2000). Environmental impacts of synthetic based fluid. New Orleans: U.S. Department on the Interior Minerals Management Service Gulf of Mexico OCS Region. OGX. (2011a). Monitoramento Ambiental realizado após a perfuração do poço Tupungato (1-OGX-20-RJS), Bloco BM-C-41, Bacia de Campos. Rio de Janeiro: OGX. OGX. (2011b). Monitoramento Ambiental realizado após a perfuração do poço Waikiki (1-OGX-25-RJS), Bloco BM-C39, Bacia de Campos. Rio de Janeiro: OGX. OPEC (Organization of the Petroleum Exporting Countries). (2015). World oil outlook. Vienna, Austria: OPEC Secretariat. Peralba, M. C. R., Pozebon, D., Santos, J. H. Z., Maia, S. M., Pizzolato, T. M., Cioccari, G., & Barrionuevo, S. (2010). Metal and hydrocarbon behavior in sediments from Brazilian shallow waters drilling activities using nonaqueous drilling fluids (NAFs). Environmental Monitoring and Assessment, 167, 33–47. Peters, K. E., Walters, C. C., & Moldowan, J. M. (2005). The biomarker guide. Cambridge: Cambridge Press. Rocha, C. B., Silveira, I. C. A., Castro, B. M., & Lima, J. A. M. (2014). Vertical structure, energetics, and dynamics of the Brazil Current System at 22°S-28°S. Journal of Geophysical Research: Oceans, 119, 52–69. Rossi-Wongtschowski, C. L. D. B., & Madureira, L. S. P. (2006). O ambiente oceanográfico da plataforma continental e do talude na região sudeste-sul do Brasil. São Paulo: EDUSP. Silveira, I. C. A., Schmidt, A. C. K., Campos, E. J. D., Godoi, S. S., & Ikeda, Y. (2000). A corrente do Brasil ao largo da costa leste brasileira. Boletim do Instituto Oceanográfico, 48(2), 171–183. Silveira, I.C.A., Calado, L., Castro, B.M., Cirano, M., Lima, J.A.M., & Mascarenhas, A.D.S. (2004). On the baroclinic structure of the Brazil current-intermediate western boundary current system at 22°–23°S. Geophysical Research Letters, v. 31(4), 2004. Simoneit, B. R. T. (1993). Hydrotermal alteration of organic matter in marine and terrestrial systems. In M. H. Engel & S. A. Macko (Eds.), Organic geochemistry – principles and applications (pp. 397–418). New York: Plenum Press. Sonangol. (2013). Projeto de Monitoramento Ambiental. Poço Gaivota, Bloco BM-C-46, Bacia de Campos. Rio de Janeiro: Sonangol.

Environ Monit Assess (2017) 189:44 Statoil. (2012). Projeto de Monitoramento Ambiental. Plataformas fixas Peregrino A e Peregrino B, Bloco BM-C7, Bacia de Campos. Rio de Janeiro: Statoil. Statoil. (2013a). Projeto de Monitoramento Ambiental. Relatório Final. Poço Peregrino Avaliação Sul, Bloco BM-C-7, Bacia de Campos, Brasil. Rio de Janeiro: Statoil. Statoil. (2013b). 2ª Campanha de monitoramento da qualidade do sedimento e biota bentônica e registro das forçantes do modelo hidrodinâmico – Plataformas fixas Peregrino A e Peregrino B – Campo de Peregrino, Bacia de Campos. Rio de Janeiro: Statoil. Statoil. (2014). Projeto de Monitoramento Ambiental. Plataformas fixas Peregrino A e Peregrino B, Bloco BM-C7, Bacia de Campos. Relatório da 3a Campanha de monitoramento – plataformas fixas Peregrino A & B. Rio de Janeiro: Statoil.

Page 11 of 11 44 Stramma, L., & England, M. (1999). On the water masses and mean circulation of the South Atlantic Ocean. Journal of Geophysical Research-Oceans, 104(C9), 20863–20883. Thomas, J.E (Org.). (2001). Fundamentos de engenharia de petróleo. Rio de Janeiro: Interciência/Petrobras. Toldo Jr., E. E., & Ayup Zouain, R. N. (2009). Environmental monitoring of offshore drilling for petroleum exploration (MAPEM): a brief overview. Deep-Sea Research II, 56, 1–3. Viana, A. R., Faugeres, J. C., Kowsmann, R. O., Lima, J. A. M., Caddah, L. F. G., & Rizzo, J. G. (1998). Hydrology, morphology and sedimentology of the Campos continental margin, offshore Brazil. Sedimentary Geology, 115, 133–157. Winter, W. R., Jahnert, R. J., & França, A. B. (2007). Bacia de Campos. Boletim de Geociências da Petrobras, 15(2), 511–529.