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0 Chemical EOR Progress in China Advances and Challenges
Harry L. Chang

1 Outline of Presentation
Overview Recent advancements Chemical EOR in China Polymer flooding ASP flooding Facilities Some controversial issues and challenges Summary

2 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

3 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

4 Recent Advancements Chemicals Laboratory Studies
Simulation and Simulators Project Design and Implementation Facilities, Monitoring, and Evaluation More Field Experiences Harry L. Chang

5 EOR Chemicals Polymers and related chemicals Surfactants
Co-surfactants Co-solvents Harry L. Chang

6 Improvements on Polymers (UT David Levitt Dissertation)
1500 ppm HPAM polymer, 23 °C, 11 s-1 10 20 30 40 50 50,000 100,000 150,000 200,000 Electrolyte Concentration [TDS, ppm] Viscosity [cp] NaCl 9:1 NaCl/CaCl2 Harry L. Chang

7 Improved Laboratory Techniques
Phase behavior/solubalization ratio High temperature and live oil Core flood techniques Harry L. Chang

8 Phase Behavior Experiments
Inexpensive technique for surfactant formulation Measure solubalization parameters/IFT’s Measure coalescence/equilibration time Determine microemulsion viscosities Specific surfactant(s) can be tailored for specific oils Harry L. Chang

9 An Excellent ME Phase Behavior
0.0 1.0 2.0 0.5 1.5 2.5 3.0 3.5 4.0 Salinity, %: 0.75 1.25 1.75 2.25 2.75

10 Interface Fluidity

11 Core Flooding High oil recovery >90% Sorw, or Sorc<0.04
Adequate mobility control Good surfactant/polymer transport Low surfactant retention Harry L. Chang

12 Simulation and Simulators
Mechanistic model for core flood and pattern simulation Calibration and field scale simulation Advanced simulators Harry L. Chang

13 Chemical EOR in China

14 Daqing Oilfield Largest polymer and ASP floods in the world
PF oil production in Daqing has been stabilized at ~200,000 bbl/d over 10 years Polymer requirement has doubled in last 10 years from ~80,000 t/yr to ~160,000 t/yr Large-scale ASP floods have been implemented since 2006 Harry L. Chang

15 Shengli Oilfield Second largest PF in China
Also has polymer manufacturing facilities Several ASP pilot tests have been conducted in the past but decided to use SP instead Harry L. Chang

16 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

17 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

18 Oil Production by Polymer Flooding Daqing Oilfield, China

19 A Typical PF Field Performance

20 Typical Pressure and Polymer Production

21 Oil Production by Polymer Flooding Shengli Oilfield, China

22 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

23 Viscosity Data of KYPAM Polymer

24 Performance of KYPAM Polymers

25 Performance of KYPAM Polymers

26 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

27 Field Examples Daqing Karamay ASP pilot simulation Harry L. Chang

28 ASP Pilot Tests Conducted in Daqing Oilfield
Harry L. Chang

29 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

30 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

31 ASP Pilot Test Well Pattern, 2Z-B9-3 Well Group Karamay Oil Field (SPE 64726)

32 ASP Slug Design and Injection Sequence (SPE 64726)

33 Modelling Core Flood - Karamay ASP Project

34 Modelling Coreflood (UTCHEM) - Karamay ASP Project

35 Modelling of Pilot Area Performance
(SPE and 64726)

36 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 (<0.5% active) SP formulations are available now Some ASP projects may be just SP with A or just P ject Harry L. Chang

37 Chemical Injection Facilities
SPSW vs. SPMW injection facilities Large-scale polymer dispersion/mixing Large-scale ASP injection facilities Emulsion treatment facilities Fully automatic modular units for pilot testing Harry L. Chang

38 A Polymer Test Injection Site, SPSW Facilities

39 SPMW Polymer injection pumps
SPMW Polymer injection system Spec.: 16 Mpa, 60 m3/hr, polymer conc., mg/l,27 injection wells SPMW Polymer injection pumps Spec.: 16 Mpa, 4 m3/hr, And 5000 mg/l polymer

40 ST200508 SPE Logo

41 Large-Scale Polymer Dispersion/Mixing

42 Polymer Dispersion Polymer Mixing

43 ASP Injection Units Prior to Shipping

44 An ASP Injection Station with 70 Wells

45 Produced Fluid Treatment Facilities
ASP Produced Fluid Treatment, 24,000 m3/d

46 A Fully Automatic Modular Pre-Factory Tested ASP Pilot Injection Facility
Designed Rate:  640 m3/day Designed Pressure:  12 Mpa Chemical Processing Includes: Dry polymer handling, processing, & maturation Dry soda ash handling, processing, & dissolution Surfactant handling & metering Water conditioning chemicals (oxygen scavenger and biocide) Nitrogen blanket Automation: Allen-Bradley PLC based with full PID Loop control for accurate chemical recipe control and data collection Special Systems Included:  R-O water softening  Fe removal system  Heat exchanger system for high temp fluid injection

47 SPE Logo

48 A Polymer Handling System Designed by
Chemor Tech and Fabricated by Dafeng/COT in China

49 ST200508 SPE Logo

50 ST200508 SPE Logo

51 ST200508 SPE Logo

52 ST200508 SPE Logo

Polymer dispersion Is fully hydration on the surface necessary? are oxygen scavenger and nitrogen blanket necessary? Polymer flooding vs. weak gels ASP vs. SP Is ASP the future? Why SP has not been emphasized? ASP and SP Slug Aqueous Phase Stability/Clarity? Harry L. Chang

54 Challenges New polymers for high temperatures (>90oC
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

55 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 compared to technology used in 70’s and 80’s

56 Summary (Cont’d) 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


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