Surface and Subsurface Requirements for Successful Implementation of Offshore Chemical Enhanced Oil Recovery
- Kirk H. Raney (Shell International Exploration & Production) | Subhash Ayirala (Saudi Aramco) | Robert W. Chin (Shell International Exploration & Production) | Paul Verbeek (FMC Technologies)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Operations
- Publication Date
- August 2012
- Document Type
- Journal Paper
- 294 - 305
- 2012. Society of Petroleum Engineers
- 4.1.5 Processing Equipment, 5.3.4 Integration of geomechanics in models, 5.7.2 Recovery Factors, 4.3.4 Scale, 4.1.2 Separation and Treating, 2.5.2 Fracturing Materials (Fluids, Proppant)
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Chemical enhanced oil recovery (EOR), including polymer and surfactant-based processes, is a method that operators consider to maximize oil recovery from onshore and offshore reservoirs. Because of the logistical, operational, and environmental differences and the footprint and required weight needed for additional injection and production equipment, offshore chemical EOR processes are challenged by greater complexity and costs as compared with onshore applications of the same technologies.
Chemical EOR commonly requires large volumes of injection chemicals, as well as demulsifiers to break produced-water/oil emulsions and inhibitors to control scale, resulting in high shipment and storage costs. The use of seawater and/or produced water for injection of the chemicals into offshore fields mandates stringent processing of both streams to allow optimal injectivity, sweep efficiency, and chemical effectiveness in the reservoir. Offshore production of saleable oil and clean water requires space- and weight-efficient oil/water-separation euipment. Currently, conventional methods for processing produced fluids fall short in both efficiency and compactness. High offshore drilling costs lead to relatively large well spacing and more difficulty in monitoring the EOR subsurface process, and lead to restrictions on the number of disposal wells. Finally, environmental restrictions limit the overboarding of toxic or poorly biodegradable EOR chemicals.
The industry is currently investigating the limiting factors pertinent to offshore chemical EOR. As a result of these efforts, new enabling chemistries and technologies are being examined for improving surface operations to allow cost-effective offshore chemical EOR to be performed in an environmentally sound and safe manner. Some of these recent chemical- and fluids-processing developments are described in this paper. Subsurface challenges to implementing offshore chemical EOR are also highlighted, along with potential solutions.
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Ali, M.A.J., Currie, P.K., and Salman, M.J. 2007. Permeability DamageDue to Water Injection Containing Oil Droplets and Solid Particles at ResidualOil Saturation. Paper SPE 104608 presented at the SPE Middle East Oil and GasShow and Conference, Bahrain, 11-14 March. http://dx.doi.org/10.2118/104608-MS.
Ayirala, S., Doe, P., Curole, M., and Chin, R. 2008. Polymer Floodingin Saline Heavy Oil Environments. Paper SPE 113396 presented at the SPEImproved Oil Recovery Symposium, Tulsa, 20-23 April.
Ayirala, S., Uehara-Nagamine, E., Matzaos, A., Chin, R., Doe, P., and van Den Hoek, P. 2010. A Designer Water Process for Offshore Low Salinity andPolymer Flooding Applications. Paper SPE 129926 presented at the SPE ImprovedOil Recovery Symposium, Tulsa, 24-28 April. http://dx.doi.org/10.2118/129926-MS.
Barnes, J.R., Dirkzwager, H., Smit, J.R., et al. 2010. Application ofInternal Olefin Sulfonates and Other Surfactants to EOR. Part 1:Structure--Performance Relationships for Selection at Different ReservoirConditions. Paper SPE 129766 presented at the SPE Improved Oil RecoverySymposium, Tulsa, 24-28 April. http://dx.doi.org/10.2118/129766-MS.
Barnes, J.R., Smit, J.P., Smit, J.R., Shpakoff, P.G., Raney, K.H., and Puerto, M.C. 2008. Development of Surfactants for Chemical Flooding atDifficult Reservoir Conditions. Paper SPE 113313 presented at the SPE/DOESymposium on Improved Oil Recovery, Tulsa, 20-23 April. http://dx.doi.org/10.2118/113313-MS.
Berger, P.D. and Lee, C.H. 2006. Improved ASP Process Using Organic Alkali.Paper SPE 99581 presented at the SPE/DOE Symposium on Improved Oil Recovery,Tulsa, 22-26 April. http://dx.doi.org/10.2118/99581-MS.
Bondor, P.L., Hite, J.R., and Avasthi, S.M. 2005. Planning EOR Projects inOffshore Oil Fields. Paper SPE 94637 presented at the SPE Latin American andCaribbean Petroleum Engineering Conference, Rio de Janeiro, 20-23 June. http://dx.doi.org/10.2118/94637-MS.
Brooks, D., Matzakos, A., Ayirala, S., Ligthelm, D., and Cense, A.2010. Designer Water™ Flooding. Paper presented at the 31st Annual Workshop andSymposium of the International Energy Agency (IEA) Collaborative Project onEnhanced Oil Recovery, Aberdeen, 16-20 October.
Cambridge Water Technology. 2009. CoMag Technology, http://www.cambridgewatertech.com/technology/comag (accessed 2010).
Chai, C.F., Adamson, G.R., Lo, S.-W. et al. 2011. St Joseph Chemical EORPilot--A Key De-Risking Step Prior to Offshore ASP Full field Implementation.Paper SPE 144594 presented at the SPE Enhanced Oil Recovery Conference, KualaLumpur, 19-21 July. http://dx.doi.org/10.2118/144594-MS.
Chang, H.L. 1978. Polymer Flooding Technology Yesterday, Today, andTomorrow. J Pet Technol 30 (8): 1113-1128. SPE-7043-PA. http://dx.doi.org/10.2118/7043-PA.
Chang, H.L., Zhang, Z.Q., Wang, Q.M., et al. 2006. Advances in PolymerFlooding and Alkaline/Surfactant/Polymer Processes as Developed and Applied inthe People's Republic of China. J Pet Technol 58 (2):84-89. SPE-89175-MS. http://dx.doi.org/10.2118/89175-MS.
Chatzis, I. and Morrow, N.R. 1984. Correlation of Capillary NumberRelationships for Sandstone. SPE J. 24 (5): 555-562.SPE-10114-PA. http://dx.doi.org/10.2118/10114-PA.
Choi, S.K., Huh, C., Bryant, S.L., and Sharma, M.M. 2009. pH SensitivePolymers for Novel Conformance Control and Polymerflood Applications. Paper SPE121686 presented at the SPE International Symposium on Oilfield Chemistry, TheWoodlands, Texas, USA, 20-22 April. http://dx.doi.org/10.2118/121686-MS.
Deng, S., Bai, R., Paul, C.J., et al. 2002. Produced water from polymerflooding process in crude oil extraction: characterization and treatment by anovel crossflow oil-water separator. Sep. Purif. Technol. 29 (3): 207-216.
Du, Y. and Guan, L. 2004. Field-scale Polymer Flooding: Lessons Learned andExperiences Gained During Past 40 Years. Paper SPE 91787 presented at the SPEInternational Petroleum Conference in Mexico, Puebla Pue, Mexico, 7-9 November.http://dx.doi.org/10.2118/91787-MS.
Flaaten, A.K., Nguyen, Q.P., Pope, G.A., and Zhang, J. 2009. ASystematic laboratory Approach to Low-Cost, High-Performance Chemical Flooding.SPE Res Eval & Eng 12 (5): 713-723. SPE-113469-PA. http://dx.doi.org/10.2118/113469-PA.
Flaaten, A.K., Nguyen, Q.P., Zhang, J., Mohammadi, H., and Pope, G.A.2010. Alkaline/Surfactant/Polymer Chemical Flooding Without the Need for SoftWater. SPE J. 15 (1): 184-196. SPE-116754-PA. http://dx.doi.org/10.2118/116754-PA.
Frising, T., Noik, C., Dalmazzone, C., Peysson, Y., and Palermo, T.2008. Contribution of the Sedimentation and Coalescence Mechanisms to theSeparation of Concentrated Water-in-Oil Emulsions. J. Dispersion Sci.Technol. 29 (6): 827-834. http://dx.doi.org/10.1080/01932690701781501.
Fulin, Y., Xizhi, Y., and Jungang, L. 2006. Daqing Pilot Shows Effectivenessof High-Concentration Polymer Flooding. Oil Gas J. 104 (9):49-53.
Goh, K.-C., Narayasamy, D., Briers, J., de Boer, F., Ibrahim, K., and Jaberi, M.Y. 2010. Asset-Wide Reconciled Production Monitoring--A Key Enablerto Successful Real-Time Field Management. Paper SPE 128654 presented at the SPEIntelligent Energy Conference and Exhibition, Utrecht, The Netherlands, 23-25March. http://dx.doi.org/10.2118/128654-MS.
Gruenenfelder, M. 2007. EOR Chemicals - What is Status? Presentation givendat the OG21 Workshop on Enhanced Recovery by Water Additives, Stavanger, 8February.
Hernandez, C., Chacon, L.J., Anselmi, L. et al. 2003. ASP System Design foran Offshore Application in La Salina Field, Lake Maracaibo. SPE Res Eval& Eng 6 (3): 147-156. SPE-84775-PA. http://dx.doi.org/10.2118/84775-PA.
Hirasaki, G.J., Miller, C.A., and Puerto, M. 2008. Recent Advances inSurfactant EOR. Paper SPE 115386 presented at the SPE Annual TechnicalConference and Exhibition, Denver, 21-24 September. http://dx.doi.org/10.2118/115386-MS.
Hirasaki, G.J., Miller, C.A., Raney, O.G., Poindexter, M.K., Nguyen, D.T.,and Hera, J. In press. Separation of Produced Emulsions fromSurfactant Enhanced Oil Recovery Processes. Energy Fuels (submitted 15August 2010). http://dx.doi.org/10.1021/ef101087u.
Huh, C. 1979. Interfacial tensions and solubilizing ability of amicroemulsion phase that coexists with oil and brine. J. Colloid InterfaceSci. 71 (2): 408-426. http://dx.doi.org/10.1016/0021-9797(79)90249-2.
Kaminsky, R.D., Wattenbarger, R.C., Szafranski, R.C., and Coutee, A.S.2007. Guidelines for Polymer Flooding Evaluation and Development. Paper IPTC11200 presented at the International Petroleum Technology Conference, Dubai,4-6 December. http://dx.doi.org/10.2523/11200-MS.
Khan, R., Lee, J., and Sams, G. 2009. Produced Water Viscosity Effectson IGF Sweeping Efficiency. Paper presented at the 2009 Annual Produced WaterSociety Seminar, Houston, January.
Koning, E.J.L., Mentzer, E., and Heemskerk, J. 1988. Evaluation of aPilot Polymer Flood in the Marmul Field, Oman. Paper SPE 18092 presented at theSPE Annual Technical Conference and Exhibition, Houston, 2-5 October. http://dx.doi.org/10.2118/18092-MS.
Levitt, D.B. and Pope, G.A. 2008. Selection and Screening of Polymers forEnhanced-Oil Recovery. Paper SPE 113845 presented at the SPE/DOE Symposium onImproved Oil Recovery, Tulsa, 19-23 April. http://dx.doi.org/10.2118/113845-MS.
Levitt, D.B., Jackson, A.C., Heinson, C., et al. 2009. The Identificationand Evaluation of High-Performance EOR Surfactants. SPE Res Eval &Eng 12 (2): 243-253. SPE-100089-PA. http://dx.doi.org/10.2118/100089-PA.
Levitt, D.B., Pope, G.A., and Jouenne, S. 2010. Chemical Degradationof Polyacrylamide Polymers Under Alkaline Conditions. Paper SPE 129879presented at the SPE Improved Oil Recovery Symposium, Tulsa, 24-28 April. http://dx.doi.org/10.2118/129879-MS.
Li, D., Shi, M.-Y., Wang, D., and Li, Z. 2009. ChromatographicSeparation of Chemicals in Alkaline Surfactant Polymer Flooding in ReservoirRocks in the Daqing Oil Field. Paper SPE 121598 presented at the SPEInternational Symposium on Oilfield Chemistry, The Woodlands, Texas, USA, 20-22April. http://dx.doi.org/10.2118/121598-MS.
Liegthelm, D.J., Gronsveld, J., Hofman, J.P., Brussee, N., Marcelis, F.,and van der Linde, H.A. 2009. Novel Waterflooding Strategy byManipulation of Injection Brine Composition. Paper SPE 119835 presented at theEUROPEC/EAGE Annual Conference and Exhibition, Amsterdam, 8-11 June. http://dx.doi.org/10.2118/119835-MS.
Liu, S., Zhang, D.L., Yan, W., Puerto, M., Hirasaki, G.J., and Miller,C.A. 2008. Favorable Attributes of Alkali-Surfactant-Polymer Flooding. SPEJ. 13 (1): 5-16. SPE-99744-PA. http://dx.doi.org/10.2118/99744-PA.
Liu, S., Zhao, X., Dong, X., Du, W., and Miao, B. 2005. Treatment ofProduced Water from Polymer Flooding Process Using a New Type of Air SpargedHydrocyclone. Paper SPE 95343 presented at the SPE Asia Pacific Health, Safetyand Environment Conference and Exhibition, Kuala Lumpur, 19-21 September. http://dx.doi.org/10.2118/95343-MS.
Maddin, C.M. 1991. Marine Toxicity and Persistence of Surfactants Used inthe Petroleum Producing Industry. Paper SPE 23354 presented at the SPE Health,Safety and Environment in Oil and Gas Exploration and Production Conference,The Hague, 11-14 November. http://dx.doi.org/10.2118/23354-MS.
Manap, A.A.A., Chong, M.O., Sai, R.M., Zainal, S., Yahaya, A.W., and Othman, M. 2011. Evaluation of Alkali-Surfactant Effectiveness by Single WellTest Pilot in a Malaysian Offshore Field Environment. Paper SPE 144150presented at the SPE Enhanced Oil Recovery Conference, Kuala Lumpur, 19-21July. http://dx.doi.org/10.2118/144150-MS.
Manrique, E.J., Thomas, C.P., Ravikiran, R., et al. 2010. EOR: CurrentStatus and Opportunities. Paper SPE 130113 presented at the SPE Improved OilRecovery Symposium, Tulsa, 24-28 April. http://dx.doi.org/10.2118/130113-MS.
Moradi-Araghi, A. and Doe, P.H. 1987. Hydrolysis and Precipitation ofPolyacrylamide in Hard Brines at Elevated Temperatures. SPE Res Eng 2 (2): 189-198.
Morel, D.C., Vert, M., Jouenne, S., Gauchet, R.R.M., and Bouger, Y. 2010.First Polymer Injection in Deep Offshore Field Angola: Recent Advances onDalia/Camelia Field Case. Paper SPE 135735 presented at the SPE AnnualTechnical Conference and Exhibition, Florence, Italy, 19-22 September. http://dx.doi.org/10.2118/135735-MS.
Nelson, R.C., Lawson, J.B., Thigpen, D.R., and Stegemeier, G.L. 1984.Cosurfactant-Enhanced Alkaline Flooding. Paper SPE 12672 presented at the SPEEnhanced Oil Recovery Symposium, Tulsa, 15-18 April. http://dx.doi.org/10.2118/12672-MS.
Osterloh, W.T. and Law, E.J. 1998. Polymer Transport and TheologicalProperties for Polymer Flooding in the North Sea Captain Field. Paper SPE 39694presented at the SPE\DOE Improved Oil Recovery Symposium, Tulsa, 19-22 April.http://dx.doi.org/10.2118/39694-MS.
Paige, R.W., Murray, L.R., Martins, J.P., and Marsh, S.M. 1995. OptimisingWater Injection Performance. Paper SPE 29774 presented at the Middle East OilShow, Bahrain, 11-14 March. http://dx.doi.org/10.2118/29774-MS.
Puerto, M., Hirasaki, G.J., and Miller, C.A. 2010. Surfactant Systems forEOR in High-Temperature, High-Salinity Environments. Paper SPE 129675 presentedat the SPE Improved Oil Recovery Symposium, Tulsa, 24-28 April. http://dx.doi.org/10.2118/129675-MS.
Puerto, M.C. and Reed, R.L. 1983. A Three-Parameter Representation ofSurfactant/Oil/Brine Interaction. SPE J. 23 (4): 669-682.SPE-10678-PA. http://dx.doi.org/10.2118/10678-PA.
Reed, R.L. and Healy, R.N. 1977. Some physico-chemical aspects ofmicroemulsion flooding: a review. In Improved Oil Recovery by Surfactant andPolymer Flooding, ed. D.O. Shah and R.S. Schechter, 383-437. New York:Academic Press.
Regtien, J.M.M. 2010. Extending The Smart Fields Concept To Enhanced OilRecovery. Paper SPE 136034 presented at the SPE Russian Oil and Gas Conferenceand Exhibition, Moscow, 26-28 October. http://dx.doi.org/10.2118/136034-MS.
Reichenbach-Klinke, R., Langlotz, B., Wenzke, B., Spindler, C., and Brodt, G. 2011. Hydrophobic Associative Copolymer with Favorable Properties forthe Application in Polymer Flooding. Paper SPE 141107 presented at the SPEInternational Symposium on Oilfield Chemistry, The Woodlands, Texas, USA, 11-13April. http://dx.doi.org/10.2118/141107-MS.
Sahni, V., Dean, R.M., Britton, C., Weerasooriya, U., and Pope, G.A. 2010.The Role of Co-Solvents and Co-Surfactants in Making Chemical Floods Robust.Paper SPE 130007 presented at the SPE Improved Oil Recovery Symposium, Tulsa,24-28 April. http://dx.doi.org/10.2118/130007-MS.
Sanz, C.A. and Pope, G.A. 1995. Alcohol-Free Chemical Flooding: FromSurfactant Screening to Coreflood Design. Paper SPE 28956 presented at the SPEInternational Symposium on Oilfield Chemistry, San Antonio, Texas, USA, 14-17February. http://dx.doi.org/10.2118/28956-MS.
Seright, R.S., Campbell, A.R., Mozley, P.S., and Han, P. 2010.Stability of Partially Hydrolyzed Polyacrylamides at Elevated Temperatures inthe Absence of Divalent Cations. SPE J. 15 (2): 341-348.SPE-121460-PA. http://dx.doi.org/10.2118/121460-PA.
Sharma, M., Taware, S.V., and Datta-Gupta, A. 2011. Optimizing Polymerfloodvia Rate Control. Paper SPE 144833 presented at the SPE Enhanced Oil RecoveryConference, Kuala Lumpur, 19-21 July. http://dx.doi.org/10.2118/144833-MS.
SNF Floerger. 2003. FLOPAM™ SF: Solvent Free Dispersion Range,http://www.snf-group.com/IMG/pdf/Dispersion-FLOPAM_SF_E.pdf (accessed2010).
Srivastava, M., Zhang, J., Nguyen, Q.P., and Pope, G.A. 2009. A SystematicStudy of Alkaline-Surfactant-Gas Injection as an EOR Technique. Paper SPE124752 presented at the SPE Annual Technical Conference and Exhibition, NewOrleans, 4-7 October. http://dx.doi.org/10.2118/124752-MS.
Stoll, W.M., al Shureqi, H., Finol, J., et al. 2010.Alkaline-Surfactant-Polymer Flood: From the Laboratory to the Field. Paper SPE129164 presented at the SPE EOR Conference at Oil & Gas West Asia, Muscat,Oman, 11-13 April. http://dx.doi.org/10.2118/129164-MS.
Thomas, S. 2006. Chemical EOR: The Past--Does It Have a Future? Presented asan SPE Distinguished Lecture (SPE-108828-DL) during the 2005-2006 season.
Visser, F. 2010. Innovation for Chemical EOR. Paper presented at the GlobalIOR & EOR Forum: Capitalising from Heavy and Maturing Fields and MaximisingProduction from the 75% of Untapped Reservoirs, Amsterdam, 29 November-1December.
Wang, D., Han, P., Shao, Z., Chen, J., and Seright, R.S. 2006. SweepImprovement Options for the Daqing Oil Field. Paper SPE 99441 presented at theSPE/DOE Symposium on Improved Oil Recovery, Tulsa, 22-26 April. http://dx.doi.org/10.2118/99441-MS.
Wang, D., Liu, C., Wu, W., and Wang, G. 2008. Development of anUltra-Low Interfacial Tension Surfactant in a System With No-Alkali forChemical Flooding. Paper SPE 109017 presented at the SPE/DOE Symposium onImproved Oil Recovery, Tulsa, 20-23 April. http://dx.doi.org/10.2118/109017-MS.
Wang, W. and Gu, Y. 2005. Experimental Studies of the Detection and Reuse ofProduced Chemicals in Alkaline/Surfactant/Polymer Floods. SPE Res Eval &Eng 8 (5): 362-371. SPE-84075-PA. http://dx.doi.org/10.2118/84075-PA.
Wang, Y., Liu, J., Liu, B., Liu, Y., Hongxing, W., and Chen, G. 2004.Why Does Scale Form in ASP Flood? How to Prevent from It?--A Case Study of theTechnology and Application of Scaling Mechanism and Inhibition in ASP FloodPilot Area of N-1DX Block in Daqing. Paper SPE 87469 presented at the SPEInternational Symposium on Oilfield Scale, Aberdeen, 26-27 May. http://dx.doi.org/10.2118/87469-MS.
Wellington, S.L. 1983. Biopolymer Solution Viscosity Stabilization--PolymerDegradation and Antioxidant Use. SPE J. 23 (6): 901-912.SPE-9296-PA. http://dx.doi.org/10.2118/9296-PA.
Wintershall. 2011. A small fungus with a big impact: oil production withbiopolymer. Fact Sheet, E&P In Brief - Spotlight on Research, Kassel,Germany (March 2011). http://www.wintershall.com/fileadmin/download/presse/jpg_2011/Facht_Sheet/110330_Fact_Sheet_JPG_Schizophyllan_EN.pdf.
Wyatt, K., Pitts, M.J., and Surkalo, H. 2002. Mature Waterfloods Renew OilProduction by Alkaline-Surfactant-Polymer Flooding. Paper SPE 78711 presentedat the SPE Eastern Regional Meeting, Lexington, Kentucky, USA, 23-26 October.http://dx.doi.org/10.2118/78711-MS.
Wyatt, K., Pitts, M.J., and Surkalo, H. 2008. Economics of Field ProvenChemical Flooding Technologies. Paper SPE 113126 presented at the SPE/DOESymposium on Improved Oil Recovery, Tulsa, 20-23 April. http://dx.doi.org/10.2118/113126-MS.
Wylde, J.J., Allan, K.J., Mcmahon, J., and Mayner, S. 2011. ScaleInhibitor Application In Northern Alberta: A Case History of an Ultra HighTemperature Scale Inhibition Solution in Fire Tube Heater Treaters. Paper SPE141100 presented at the SPE International Symposium on Oilfield Chemistry, TheWoodlands, Texas, USA, 11-13 April. http://dx.doi.org/10.2118/141100-MS.
Xiang, W. and Zhou, W. 2011. Field Experience of Produced Polymer Control inOffshore Oilfield. Paper SPE 144277 presented at the SPE Enhanced Oil RecoveryConference, Kuala Lumpur, 19-21 July. http://dx.doi.org/10.2118/144277-MS.
Zaitoun, A. and Potie, B. 1983. Limiting Conditions for the Use ofHydrolyzed Polyacrylamides in Brines Containing Divalent Ions. Paper SPE 11785presented at the SPE Oilfield and Geothermal Chemistry Symposium, Denver, 1-3June. http://dx.doi.org/10.2118/11785-MS.
Zhao, P., Jackson, A.C., Britton, C. et al. 2008. Development of HighPerformance Surfactants for Difficult Oils. Paper SPE 113432 presented at theSPE/DOE Symposium on Improved Oil Recovery, Tulsa, 20-23 April. http://dx.doi.org/10.2118/113432-MS.
Zheng, F. and Sams, G. 2010. The Impact of Polymer in Oil Separation andProduced Water Treatment. Paper presented at the 20th Annual Produced WaterSociety Seminar, Houston, 20-22 January.
Zheng, F.F., Quiroga, P., and Sams, G. 2011. Challenges in ProcessingProduced Emulsion from Chemical Enhanced Oil Recovery - Polymer Flood UsingPolyacrylamide. Paper SPE 144322 presented at the SPE Enhanced Oil RecoveryConference, Kuala Lumpur, 19-21 July. http://dx.doi.org/10.2118/144322-MS.
Zhou, W., Zhang, J., Feng, G. et al. 2008. Key Technologies of PolymerFlooding in Offshore Oilfield of Bohai Bay. Paper SPE 115240 presented at theSPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, 20-22October. http://dx.doi.org/10.2118/115240-MS.