Technologies for Oil and Gas Produced Water Treatment Biodegradation
Micro-organisms used in the biological treatment of produced water can degrade different suspended and dissolved oils, volatile acids and other soluble organic compounds. A number of different aerobic and anaerobic biological processes have been used for treating oil- and gasfield produced water. These include:4
• activated sludge; • trickling filters; • sequencing batch reactors; • chemostate reactors; • biological aerated filters; • waste stabilisation ponds; • membrane bioreactors; and • lagoons.
In the US, the Los Alamos National Laboratory has developed a new treatment system.14
This three-part treatment system (see Figure 9) includes a surface modified zeolite (SMZ) to remove light hydrocarbon
No single technology can meet suitable effluent characteristics; thus two or more treatment systems may have to be used in series.
components; a vapour phase bioreactor (VPB) to remove volatile compounds; and a membrane bioreactor (MBR). The membrane bioreactor permeate is fed into the reverse osmosis system for desalination. The result is clean water that can be used for industrial and/or agricultural purposes or be safely reintroduced into a water system.
A simpler treatment system for the treatment and re-use of produced waste-water, consisting of a crossflow membrane sequencing batch reactor (MSBR) and a MSBR/reverse osmosis process, has been tested
1.
Veil JA, Puder MG, Elcock D, Redweik RJ Jr., A white paper describing produced water from production of crude oil, natural gas, and coal bed methane, US Department of Energy, National Energy Technology Laboratory, 2004.
2.
Reynolds RR, Kiker RD, Produced water and associated issues. A manual for the independent operator, South Midcontinent Region of the Petroleum Technology Transfer Council, 2003.
3.
Dal Ferro B, Smith M, Global onshore and offshore water production, Touch Oil and Gas, 2007. Available at:
www.touchoilandgas.com/global-onshore-offshore-water- a7137-1.html (accessed 30 September 2011).
4. 5.
Fakhru’l-Razi A, Pendashteh AR, Abdullah LC, et al., Review of technologies for oil and gas produced water treatment, J Hazard Mater, 2009;170(2–3):530–51.
Hansen BR, Davies SRH, Review of potential technologies for the removal of dissolved components from produced water: Oil and natural gas production, Chemical Engineering Research and Design, 1994;72(2):176–88.
6. Khatib Z, Produced water management: is it a future legacy or a business opportunity for field development? Presented at: International Petroleum Technology Conference, Dubai, UAE, 4–6 December 2007.
7. Arthur JD, Langhus BG, Patel C, Technical Summary of Oil and Figure 10: Schematic Typical Reverse Osmosis Treatment System16
Chemical addition
Reverse osmosis system Brine water cartridge filter 5 mm
Sand filter
Activated carbon filter
Pre-treatment
successfully. The MSBR was inoculated with a consortium of isolated halophilic micro-organisms. A high removal efficiency of COD and total organic carbon were achieved at moderate total dissolved solids (100,000 mg/l). The MSBR effluent concentration levels met the required standard for oil well re-injection. The reverse osmosis treatment reduced the salt and organic content to acceptable levels for irrigation and various industrial re-uses.15
Desalination
Different technologies, including warm softening, ion exchange, thermal distillation and reverse osmosis membrane, can desalinate produced water. In reverse osmosis processes, pure water diffuses through a semi-permeable membrane, leaving behind waste with high- total dissolved solids. Raw produced water should be pre-treated before reverse osmosis to reduce fouling. Figure 10 shows a typical reverse osmosis treatment unit at an offshore platform.16
Conclusions
In produced water treatment, no single technology can meet suitable effluent characteristics; thus two or more treatment systems may have to be used in series. The choice of the best technology is based on produced water chemistry, cost-effectiveness, space availability, re-use and discharge plans, durable operation and by-products. Although raw produced water is toxic, by using suitable technology, it can be treated for different types of re-use – even as drinking water. Such re-use of water is especially important in water-stressed and arid countries. n
Gas Produced Water Treatment Technologies, ALL Consulting, 2005. Available at:
www.all-
llc.com/publicdownloads/ALLConsulting- WaterTreatmentOptionsReport.pdf (accessed 30 September 2011).
8. Owens N, Lee DW, The use of micro bubble flotation technology in secondary and tertiary produced water treatment – a technical comparison with other separation technologies, GLR Solutions, 2007. Available at:
www.glrsolutions.com/media/White_Paper_Comp_Tech.pdf (accessed 30 September 2011).
9. Pan America Environmental, Oil and fuel removal, Tech File no 1000, 2004. Available at: www.wash-water-
treatment.com/1000.pdf (accessed 30 September 2011).
10. Prosep, Produced water treatment: selecting the right equipment for your application, O&G Next Generation, 2011. Available at:
www.ngoilgas.com/article/Issue-4/Health,- Safety-AND-Environment/Produced-Water-Treatment- Selecting-the-Right-Equipment-for-Your-Application/ (accessed 30 September 2011).
11. Plebon MJ, Saad M, Fraser S, Further advances in produced water de-oiling utilizing a technology that removes and recovers dispersed oil in produced water 2 microns and larger. Presented at: 12th International Petroleum Environmental Conference,
Houston, 8–11 November 2005.
12. Zaidi A, Simms K, Kok S, Nelson R, Recent advances in the application of membrane technology for the removal of oil and suspended solids from produced waters. In: Ray JP, Engelhardt FR (eds), Produced Water:
Technological/Environmental Issues and Solutions, New York: Plenum Press, 1992;489–502.
13. New Logic Research, Using VSEP to treat produced water. An effective and economical solution, 2004. Available at:
www.vsep.com/pdf/ProducedWater.pdf (accessed 30 September 2011).
14. Los Alamos National Laboratory, System for treatment of co-produced water, 2007. Available at:
www.lanl.gov/orgs/tt/pdf/techs/smz_vbp.pdf (accessed 30 September 2011).
15. Fakhru’l-Razi A, Pendashteh AR, Abidin ZZ, et al., Application of membrane-coupled sequencing batch reactor for oilfield produced water recycle and beneficial re-use, Bioresour Technol, 2010;101(18):6942–9.
16. Morales G, Barrufet M, Desalination of produced water using reverse osmosis, GasTIPS, Summer 2002:13–7. Available at:
http://media.godashboard.com/gti/4ReportsPubs/4_7GasTips/ Summer02/DesalinationOfProducedWater.pdf (accessed 30 September 2011).
Permeat Pump
Concentrate or reject
EXPLORATION & PRODUCTION – VOLUME 9 ISSUE 2
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