Chemical EOR Progress in China Advances and Challenges Harry L. Chang Harrylchang@chemortech.com www.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 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

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

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 2.0 0.5 1.5 2.5 3.0 3.5 4.0 Salinity, %: 0.75 1.25 1.75 2.25 2.75

Interface Fluidity

Core Flooding High oil recovery >90% Sorw, or Sorc<0.04 Adequate mobility control Good surfactant/polymer transport Low surfactant retention 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 Flooding Daqing Oilfield, China

A Typical PF Field Performance

Typical Pressure and Polymer Production

Oil Production by Polymer Flooding Shengli Oilfield, China

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 Group Karamay 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 ject 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 SPMW Polymer injection system Spec.: 16 Mpa, 60 m3/hr, polymer conc., 1000 mg/l，27 injection wells SPMW Polymer injection pumps Spec.: 16 Mpa, 4 m3/hr, And 5000 mg/l polymer

ST200508 SPE Logo

Large-Scale Polymer Dispersion/Mixing 41

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

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

ST200508 SPE Logo

ST200508 SPE Logo

ST200508 SPE Logo

ST200508 SPE Logo

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

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