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Chemical EOR Progress in China Advances and
ChallengesHarry L. ChangHarrylchang@chemortech.c
omwww.chemortech.com
Outline of Presentation
Overview Recent advancements Chemical EOR in China
Polymer flooding ASP flooding Facilities
Some controversial issues and challenges
Summary
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
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
Recent Advancements
Chemicals Laboratory Studies Simulation and Simulators Project Design and Implementation Facilities, Monitoring, and Evaluation More Field Experiences
Harry L. Chang
EOR Chemicals
Polymers and related chemicals
Surfactants Co-surfactants Co-solvents
Harry L. Chang
Improvements on Polymers
(UT David Levitt Dissertation)
Harry L. Chang
Improved Laboratory Techniques
Phase behavior/solubalization ratio High temperature and live oil Core flood techniques
Harry L. Chang
Phase Behavior Experiments
• 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
An Excellent ME Phase Behavior
0.0 1.0 2.00.5 1.5 2.5 3.0 3.5 4.0Salinity, %: 0.75 1.25 1.75 2.25 2.75
Increas ing Electrolyte Concentration
Interface Fluidity
High oil recovery>90% Sorw, or Sorc<0.04
Adequate mobility control Good surfactant/polymer transport Low surfactant retention
Core Flooding
Harry L. Chang
Simulation and Simulators
Mechanistic model for core flood and pattern simulation
Calibration and field scale simulation
Advanced simulators
Harry L. Chang
Chemical EOR in China
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
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
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
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
Oil Production by Polymer FloodingDaqing Oilfield, China
0
100
200
300
400
500
600
700
800
900
1000
1993 1995 1997 1999 2001 2003 2005 2007 2009
Year
Oil
Ra
te b
y P
oly
me
r F
loo
din
g,
mm
bb
ls PF Ann. Rate, mmbbls
Cum. Prod., mmbbls
A Typical PF Field Performance
Typical Pressure and Polymer Production
Oil Production by Polymer FloodingShengli Oilfield, China
0
20
40
60
80
100
120
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160
180
200
1997 1999 2001 2003 2005 2007 2009
Year
Oil
Ra
te b
y P
oly
me
r F
loo
din
g, m
mb
bls
PF Ann. Rate, mmbbls
Cum. Prod., mmbbls
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
Viscosity Data of KYPAM Polymer
Concentration
Performance of KYPAM Polymers
Performance of KYPAM Polymers
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
Field Examples
Daqing Karamay ASP pilot simulation
Harry L. Chang
ASP Pilot Tests Conducted in Daqing Oilfield
Harry L. Chang
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
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
ASP Pilot Test Well Pattern, 2Z-B9-3 Well GroupKaramay Oil Field (SPE 64726)
ASP Slug Design and Injection Sequence
(SPE 64726)
PAM
PAM
Modelling Core Flood - Karamay ASP
Project
Modelling Coreflood (UTCHEM) - Karamay ASP Project
Modelling of Pilot Area Performance (SPE 39610 and 64726)
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
Harry L. Chang
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
A Polymer Test Injection Site, SPSW Facilities
SPMW Polymer injection pumps
Spec.: 16 Mpa, 4 m3/hr, And 5000 mg/l polymer
SPMW Polymer injection systemSpec.: 16 Mpa, 60 m3/hr, polymer conc., 1000 mg/l , 27 injection wells
ST200508 SPE Logo 41
42
Large-Scale Polymer Dispersion/Mixing
Polymer Dispersion Polymer Mixing
ASP Injection Units Prior to Shipping
An ASP Injection Station with 70 Wells
Produced Fluid Treatment Facilities
ASP Produced Fluid Treatment, 24,000 m3/d
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
SPE Logo 48
A Polymer Handling System Designed by
Chemor Tech and Fabricated by Dafeng/COT in China
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
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
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 70’s and 80’s
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
THANK YOU!
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