Chemical characterization and statistical analysis of heavy metals produced discharges from South Pars Gas offshore for dispersion modeling

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1 Bulgrin Chemicl Communictions, Volume 47, Specil Issue D (pp ) Chemicl chrcteriztion nd sttisticl nlysis of hevy metls produced dischrges from South Prs Gs offshore for dispersion modeling S.H. Ftemi 1*, A.H. Jvid 2, P. Nsiri 1, M. Mirilvsni 1 1 Grdute School of Environmentl Engineering, Science nd Reserch Brnch, Islmic Azd University, Tehrn, Irn 2 Grdute School of Mrine Science nd Technology, Science nd Reserch Brnch, Islmic Azd University, Tehrn, Irn Received June 26, 2015, Revised September 10, 2015 The most significnt energy development project, the South Prs field, produces bout 44 percent of totl nturl gs in Irn. Discovered in 1990 nd locted 62 miles offshore in the Persin Gulf, South Prs hs 24-phse development scheme. Phses 1-10, which re in production mode nd re llocted for the domestic mrket for consumption nd reinjection for EOR Produced wter is the lrgest effluent dischrge ssocited with South Prs offshore gs production. The totl volume of produced wter effluent is expected to increse with future nticipted development of offshore gs reserve. The environmentl impct potentilly cused by produced wter is relted to the fte nd trnsport of its individul components including orgnic nd inorgnic compounds (e.g., petroleum hydrocrbons, hevy metls, nutrients, nturl rdionuclides) ssocited with the formtion wter nd treting chemicls. Although produced wter dischrges re ssocited with rpid dilution nd low-to-trce levels of pollutnts, the potentil for cumultive toxic effects under regionl ocen currents wrrnts need to ssess the long-term risks to the mrine ecosystems. In this pper t first the quntity nd qulity of produced wter re mesured nd reported for one yer nd some sttisticl reviews hs done. Determintion of the hevy metls of effluent wter - extrction nd infr-red spectrometric nd OSPAR reference method which is the stndrd method for dispersed hevy metls in produced wter nlysis in the UK for both oil nd gs fcilities used s stndrd method. Advection, diffusion nd fte of hevy metl by wind nd tidl currents nd trnsport re indirectly tken into ccount in this study. Hydrodynmic, hevy metl nd pth of the hevy metl in Offshore Gs Pltforms in South Prs Gs Field in 3 month hs been simulted. Keywords: Hevy Metls, Dispersion, Sttisticl, Anlysis, Modelling, Persin Gulf INTRODUCTION Incresingly, offshore outflls re being used for the disposl of wstewter in costl res. Becuse the dischrged effluents generlly exert different velocity, temperture, nd density compred with the receiving wter body, wste dischrges form plumes nd jets with high momentum nd different densities [1,2,3]. The mixing nd dispersion processes of continuous dischrge into receiving wter body cn be divided into ner-field, fr-field, nd intermedite regions ccording to length nd time scle. In the vicinity of the dischrge point, the jet trjectory nd mixing re dominted by the momentum of the dischrges nd the density differences between dischrges nd the receiving wter body. This region is referred to s the ner field, where the typicl time nd length scles of the plume re in the order of minutes nd wter depths (tens to hundreds of meters), respectively. After some time, or some distnce, from the dischrge point, the influence of the inflow To whom ll correspondence should be sent: E-mil: hmidrezftemi@yhoo.com; chrcteristics dissiptes nd mbient flow conditions then control trnsport nd mixing of the dischrges. This region, where the diluted effluents re diffused with ocen currents, is referred to s the fr field, where the typicl time nd length scles re in the order of hours nd kilometers. Between these two regions, there is zone clled the intermedite field, which strts t the end of the jet regime [2,4,5]. The intermedite field my extend over distnces greter thn the wter depth under conditions of wek mbient flow; however, under strong mbient conditions, intermedite-field processes cn be fr less significnt thn fr-field dispersion processes. There is incresing environmentl concern over the ocen dischrge of contminnts, such s metls nd hydrocrbons, in produced wter becuse of their potentil for bioccumultion nd toxicity, prticulrly by those dissolved in the wter phse. It is noted tht hydrocrbons nd hevy metls show different fte nd trnsport mechnisms due to their differences in physico-chemicl properties. Low concentrtions of hydrocrbons in lrge dischrge of produced wter cn be rpidly diluted by tidl currents nd decy over time due to erobic degrdtion. Thus, 2015 Bulgrin Acdemy of Sciences, Union of Chemists in Bulgri

2 S. H. Ftemi et l.: Chemicl chrcteriztion nd sttisticl nlysis of hevy metls produced dischrges from the effects of hydrocrbons ssocited with produced wter dischrges re primrily linked to loclized res nd unlikely to cuse lrge-scle environmentl impcts. In contrst, lrge number of hevy metls re stble, environmentlly persistent, nd highly toxic. Furthermore, they cn be ccumulted by mrine life in concentrtions severl thousnd times higher thn those in the surrounding sewter [3]. For exmple, led (Pb) is highly toxic metl with persistent dverse effects in the mrine ecosystem, nd the toxic effects on shell_ sh cn occur even in the presence of very low concentrtion of Pb [5, 6, 7]. Produced wter is the lrgest volume wste strem in the explortion nd production process of oil nd gs. Over the economic life of producing field, the volume produced wter cn exceed by ten times the volume of hydrocrbon produced. During the lter stges of production, produced wter cn ccount for s much s 98 % of the extrcted fluids. Typicl wter production rtes from oil pltforms re from to m 3 /dy nd for gs pltforms 1, 6-30 m 3 /dy [6, 8]. These mounts to n expected dischrge of produced wter to the North Se in 1998 of 3, 4 x 108 m 3. When dischrged the produced wter still contins wide rnge of components: dissolved orgnic components, vrious production chemicl trce metls, nturlly occurring rdioctive mteril, inorgnic slts. In ddition the dischrged wter is lmost depleted for oxygen nd hs n verge COD or BOD vlue of mg O 2/l [5, 8, 9, 10]. In ddition to the orgnic components trce elements s Pb, Cd, Cu, Hg, Ni, Zn, As nd Cr re dissolved in the produced wter in considerbly greter concentrtions thn in se wter [11, 12]. In this field, 11 pltforms (we know s SPD) re in production mode nd very pltforms normlly hve gs wells. The lyout nd configurtion of these pltforms hs shown in Fig.1. Tretment Pckge tht is common to both trins [13]. Typicl produced wter flow digrms of pltforms which re studied re shown in Fig.2. Fig. 2. Typicl produced wter flow digrm of pltforms nd Hevy Metl Chnges in Se The pckge is designed to process feed rte of 2000 bpd (brrels per dy) liquids nd to reduce suspended oil in wter content of the seprted wter to 40 ppm wt. mx [8]. Prior to disposl overbord vi disposl cisson. The Oily Wter Tretment Pckge comprises: Hydro cyclones (two per FWKO Drum one operting, one instlled spre - nd one for Test Seprtor). A wter degssing drum this hndles the wter from the hydro cyclones nd the colescing vessels. Reject oil from the hydro cyclones enters directly into the oil comprtment of the drum. Filters nd colescer filters these hndle wter from degssing drum before dischrge to se. The treted wter from the colescer filters is dischrged to the se vi the cisson. The reject strem from the OWTP (recovered condenste in wter) is recycled bck to the inlet of the FWKO Drum vi the Flre KO Drum nd Condenste Injection Pumps, due to its high wter content. Fig. 1. The South Prs Gs Pltforms lyout On the pltforms, in process digrm seprted wter from the FWKO (Free Wter Knock Out) drums nd Colesces is routed to the Oily Wter METHOD The dt of produced wter dischrges nd nlyticl results re gthered through one yer nd sttisticl review hs done. The IP 426:98 (04), Determintion of the oil content of effluent wter - Extrction nd infr-red spectrometric nd OSPAR Reference Method which is the stndrd method for dispersed oil in produced wter nlysis in the UK for both oil nd gs fcilities used s stndrd method (See Figure 3). 159

3 S. H. Ftemi et l.: Chemicl chrcteriztion nd sttisticl nlysis of hevy metls produced dischrges from minute in Southern- Northern direction, nd the geogrphicl 2 minute in Western-Estern direction relted to ETOPO1 ltimetry dt in NOAA site. So by the use of these dt in 0.10 structure, the ltimetry fetures of the plce is counted nd rendered in model (Fig. 4 nd Fig. 5). Tidl surfce elevtion in Hormoz sttion utilized for Flow Model FM boundry condition tht shown in Fig 5. By using Prticle Trcking model of MIKE21, DHI, pth of hevy metl hs been simulted. Fig.3. Infr-red spectroscope In this method smple of the dischrge wter to be nlyzed is cidified to low ph (<2), extrcted with two volumes of Tetrchloroethylene (TTCE) or n lterntive solvent pproved by DECC, nd the IR bsorbnce mesured using n infrred nlyzer with fixed wvelength of 2930 cm -1. The oil content of the smple is determined by comprison of the infrred bsorbencies of the extrct ginst clibrtion grph prepred using series of stndrds contining known hevy metls [9]. The SPSS softwre for sttisticl ssessment is used for nlysis of produced wter rte nd oil content in ll pltforms. MEASUREMENT DATA The quntity nd qulity of produced wter re mesured nd reported for one yer nd ssumed for modeling nd some sttisticl reviews. Tble 1 includes oil content of produced wter dischrge nd hevy metls within 3 months on the pltform no5. An verge of dily BBL of produced wter dischrges per ech pltforms nd verge of hevy metls components re shown in Tble 1. Sttisticl review by SPSS strted with Mnov method for 8 pltforms hevy metls dt in 26 times mesurement. It ssumed tht smpling ws rndom nd error of first type ws =0.05. This nlysis shows tht dt of pltforms re cceptble nd useful for input of mthemticl modeling which is n effective tool for the mngement of Persin Gulf opertionl pltforms oily wter dischrges. Two soft wres; MIKE 21/3 (DHI 2007) nd Delft3D (Delft3D 2009) re proposed softwre s for predictions of ocen hydrodynmics; pollutnt fte nd trnsport in the fr field; wter qulity nd sediment processes (See Figure 4 nd Figure 5). MODEL SETUP To order the model input dt the bthymetry is used by structure distnces of geogrphicl width 2 Fig.4. Mesurement dt gthering in gs pltforms Tble 1. Dt of hevy metls in pltforms no. 5 Fe Cr Pb Cd Mo Ni

4 Bulgrin Chemicl Communictions, Volume 47, Specil Issue D (pp ) 2015 Tble 2. Multivrite Tests Effect Vlue F Hypothesis df Error df Sig. Pilli's Trce.999 Intercept Wilks' Lmbd.001 Hotelling's Trce Roy's Lrgest Root Pilli's Trce Pltform Wilks' Lmbd Hotelling's Trce Roy's Lrgest Root b Exct sttistic b. The sttistic is n upper bound on F tht yields lower bound on the significnce level. c. Design: Intercept + pltform includes hydrodynmic model nd qulittive wter model from produced wter which hs been done for yer for ech dischrge loction. Fig. 5. Bthymetric dt prticle trcking models. RESULTS In this reserch hydrodynmic prmeters such s tidl surfce elevtion tht mesured in in Diier Port hve been used for model vlidtion. Compre between numericl results nd field mesurements shown good greement between numericl results nd field mesurements in Diier Port. Hydrodynmic results of model hve been shown in Fig 6. The model shows the trcking of hevy metls from in offshore gs pltforms in South Prs Gs Field for 6 month (See the 4 Shpes in Fig 6). Dispersion modeling of hevy metls, which CONCLUSIONS AND DISCUSSION Gthering of sound nd cceptble dt for modeling is very importnt step of work. In this pper we submit few tbles of dt which hs produced by stndrd smpling nd lb tests. Then sttisticl review report hs submitted bsed on SPSS softwre nd it proved tht these dt re useful for next step of modeling. In this pper t first the quntity nd qulity of produced wter re mesured nd reported for one yer nd some sttisticl reviews hs done. In ddition to the orgnic components trce elements s Pb, Cd, Cu, Hg, Ni, Zn, As nd Cr re dissolved in the produced wter in considerbly greter concentrtions thn in se wter the risk ssessment of tht high environment risk ner Booshehr seside nd trnsition of hevy metls ws indirect of northwest of Persin gulf. 161

5 S. H. Ftemi et l.: Chemicl chrcteriztion nd sttisticl nlysis of hevy metls produced dischrges from Fig. 6. Trcking of hevy metls from in offshore gs pltforms in South Prs Gs Field for 6 month. REFERENCES 1. P. Tklich, X. B. Cho, Proceedings of the Interntionl Oil Spill Conference, Mrch 2001, Florid, Wshington DC, 2001, p J.A. Fy, The Spred of Oil Slick on Clm Se, Hoult, D.P. (Ed), Oil on the Se. Plenum Press, New York, NY, 1969, p Perinez, R.2005, Modeling the Dispersion of Rdio Nuclides in the Mrine Environment Springer 4. D Mcky, S. Pterson, K. Trudel, A Mthemticl Model of Oil Spill Behvior, Environmentl Protection Service, Fisheries nd Environmen Cnd, A. Johnsen., Spill Technol. Newslett., III, 134 (1982). 6. M. Fings, J. Advnce Mrine Technol., 11, 41 (1994). 7. A.J. Elliot, Deutsche Hydrogrphische Zeitschrift, 39, 113 (1986). 8. A. F.Blumberg, G. L.Mellor, A description of three-dimensionl costl ocen circultion model. Geophysicl Fluid Dynmics Progrm, Princeton University, Princeton, NJ, G. W. Bryn, W. J. Lngston, Environ. Pollut., 76, 89 (1982). 10. Z. Chen, G. H. Hung, J. of Environ. Eng. Div. ASCE, 129(1), 79 (2003). 11. J. R. Dojlido, G.A. Best, Chemistry of wter nd wter pollution. Ellis Horwood Ltd, Chichester, UK P. Foster, Environ. Pollut., 10, 45 (1976). 13. P. A. Gillibrnd, R.Stgg, W. R. Turrell, ICES CM/c, 11, 421 (1995). 162