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

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EOR Chemicals

Polymers and related chemicals

Surfactants Co-surfactants Co-solvents

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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

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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

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Simulation and Simulators

Mechanistic model for core flood and pattern simulation

Calibration and field scale simulation

Advanced simulators

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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

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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

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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

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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

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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

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Field Examples

Daqing Karamay ASP pilot simulation

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ASP Pilot Tests Conducted in Daqing Oilfield

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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

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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

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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

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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

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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

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A Polymer Handling System Designed by

Chemor Tech and Fabricated by Dafeng/COT in China

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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!