chemical eor progress in china advances and challenges

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)

1500 ppm HPAM polymer, 23 °C, 11 s-1

0

10

20

30

40

50

0 50,000 100,000 150,000 200,000

Electrolyte Concentration [TDS, ppm]

Visc

osity

[cp]

NaCl

9:1 NaCl/CaCl2

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 ConcentrationInterface 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 2009Year

Oil

Rat

e by

Pol

ymer

Flo

odin

g, m

mbb

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

140

160

180

200

1997 1999 2001 2003 2005 2007 2009

Year

Oil

Rat

e by

Pol

ymer

Flo

odin

g, m

mbb

ls

PF Ann. Rate, mmbblsCum. 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

visc

osit

y

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 testingHarry 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!