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Chemical EOR Progress in China Advances and Challenges Harry L. Chang Harrylchang@chemortech.com www.chemortech.com Slide 2 Outline of Presentation Overview Recent advancements Chemical EOR in China Polymer flooding ASP flooding Facilities Some controversial issues and challenges Summary Slide 3 Chemical EOR Global Status China has most field experiences US has focused on improvements in chemicals, lab studies, and simulators Increased chemical EOR mechanistic understandings and field activities in US and world-wide in recent years Harry L. Chang Slide 4 General Understanding Polymer flooding (PF): A mature EOR process Polymer gels: Used successfully in water shut- off and profile modification in selected reservoirs Surfactant-polymer (SP): Effective but expensive ASP: Effective, less expensive, but requires extensive treatment of injection/produced fluids Harry L. Chang Slide 5 Recent Advancements Chemicals Laboratory Studies Simulation and Simulators Project Design and Implementation Facilities, Monitoring, and Evaluation More Field Experiences Harry L. Chang Slide 6 EOR Chemicals Polymers and related chemicals Surfactants Co-surfactants Co-solvents Harry L. Chang Slide 7 Improvements on Polymers (UT David Levitt Dissertation) 1500 ppm HPAM polymer, 23 C, 11 s -1 0 10 20 30 40 50 0 50,000100,000150,000 200,000 Electrolyte Concentration [TDS, ppm] Viscosity [cp] NaCl 9:1 NaCl/CaCl 2 Harry L. Chang Slide 8 Improved Laboratory Techniques Phase behavior/solubalization ratio High temperature and live oil Core flood techniques Harry L. Chang Slide 9 Phase Behavior Experiments Phase behavior experiments Inexpensive technique for surfactant formulation Measure solubalization parameters/IFTs Measure coalescence/equilibration time Determine microemulsion viscosities Specific surfactant(s) can be tailored for specific oils Harry L. Chang Slide 10 An Excellent ME Phase Behavior 0.01.02.00.51.52.53.03.54.0Salinity, %:0.751.251.752.252.75 Slide 11 Interface Fluidity Slide 12 High oil recovery >90% S orw, or S orc PF in China Showed Incremental recovery depends on reservoir quality polymer selection polymer amount, > 500 ppm.pv now Production of polymer and emulsions may be expected Large scale injection/production facilities are necessary for successful operations Harry L. Chang Slide 18 Polymer Flooding also Showed Simplified field operations have been practiced in field-wide operations On-site polymer production would improve the economics KYPAM polymers appears to be more effective in high perm and high salinity reservoirs Visco-elastic behavior can reduce Sor (SPE127453) CDG will enhance PF performance Harry L. Chang Slide 19 Oil Production by Polymer Flooding Daqing Oilfield, China Slide 20 A Typical PF Field Performance Slide 21 Typical Pressure and Polymer Production Slide 22 Oil Production by Polymer Flooding Shengli Oilfield, China Slide 23 KYPAM Polymers Comb like with short branched chain to maintain effectiveness in high salinity brines Wide MW range for reservoirs with different permeabilities Successfully applied in some reservoirs in China Harry L. Chang Slide 24 Viscosity Data of KYPAM Polymer Concentration viscosity Slide 25 Performance of KYPAM Polymers Slide 26 Slide 27 ASP Floods in China Pilot testing: Daqing, Shengli, Karamay Large scale field projects in Daqing Large scale injection/production facilities have been developed in Daqing Emulsion and scale productions were observed Harry L. Chang Slide 28 Field Examples Daqing Karamay ASP pilot simulation Harry L. Chang Slide 29 ASP Pilot Tests Conducted in Daqing Oilfield Harry L. Chang Slide 30 ASP Results in Daqing High incremental recovery Severe emulsion production Severe scale production SP with A instead of ASP? One of the most difficult oil for SP flooding Harry L. Chang Slide 31 Karamay ASP Pilot Test Design and Field Performance (SPE 64726) Process design/management: Harry Chang Project implementation: Karamay Oilfield A single surfactant system using petroleum sulfonates produced in a local refinery Applied the salinity gradient with STPP for sequestration Slide 32 ASP Pilot Test Well Pattern, 2Z-B9-3 Well Group Karamay Oil Field (SPE 64726) Slide 33 ASP Slug Design and Injection Sequence (SPE 64726) PAM Slide 34 Modelling Core Flood - Karamay ASP Project Slide 35 Modelling Coreflood (UTCHEM) - Karamay ASP Project Slide 36 Modelling of Pilot Area Performance (SPE 39610 and 64726) Slide 37 Some Comments on ASP ASP requires special crude oils to improve performances ASP slug cost less but other costs would be substantial (treating injection brine and produced fluids) Low surfactant concentration ( Challenges New polymers for high temperatures (>90 o C Modeling polymer visco-elastic effects Low MW polymers for low perm. reservoirs Surfactants with low adsorption and other additives Low cost and effective emulsion breakers New scale prevention technologies Harry L. Chang Slide 56 Summary A large number and variety of high performance surfactants and polymers are now available for EOR Chemical flooding is now being used for highly viscous crudes, under higher salinity and higher temperature conditions Low cost and more effective lab methods have been developed for chemical formulations High recovery efficiency (>90% OOIP) has been obtained in low permeability sandstone and dolomite reservoir cores The amount of surfactant needed to recovery the oil has been reduced by a factor of 2 - 5 compared to technology used in 70s and 80s Slide 57 Summary (Contd) Polymer flooding has been applied in commercial scales ASP and SP have only been applied successfully in pilot scales Many challenges are still remained in the future in chemical flooding Large resources are available for chemical flooding Harry L. Chang Slide 58 THANK YOU!