Chemical EOR Progress in China Advances and Challenges

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-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 Salinity, %: 0. 0 0. 5 0. 75 1. 0 1. 25 1. 75 2. 0 2. 25 2. 75 3. 0 3. 5 4. 0

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 (SPE 127453) § 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 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, 2 Z-B 9 -3 Well Group Karamay Oil Field (SPE 64726)

ASP Slug Design and Injection Sequence (SPE 64726) 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 system Spec. : 16 Mpa, 60 m 3/hr, polymer conc. , 1000 mg/l，27 injection wells SPMW Polymer injection pumps Spec. : 16 Mpa, 4 m 3/hr, And 5000 mg/l polymer

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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 m 3/d

A Fully Automatic Modular Pre-Factory Tested ASP Pilot Injection Facility • • • Designed Rate: 640 m 3/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 (>90 o. C 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!