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
Concentration

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)
PAM
PAM

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/Mixing41

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

53. SOME CONTROVERTIAL ISSUES
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

57. THANK YOU!