Rhodia/Poweltec

1. Rhodia/Poweltec Visosifying Surfactant for Chemical EOREOR Workshop “Mario Leschevich”, 3-5 Nov. 2010Mikel Morvan, Guillaume Degré, Rhodia Alain Zaitoun, Jérôme Bouillot, Poweltec.

2. Introduction to viscosifying surfactants for EOR Rhodia and Poweltec methodology: application to synthetic field cases Viscosity measurements Fluid propagation tests Core flood tests Viscosifying surfactant: application to field case Conclusion Contents

3. Introduction to viscosifying surfactants for EOR Packing Parameter (P) = VH/(lc.a0) Spherical micelles P ~ 1/3 Cylindrical micelles P~ 1/3 to ½ (Wormlike micelles or Hexagonal phases) Lamellar phase P ~ 1 • Introduction to surfactant mesophases in aqueous solutions Molecular dimension, concentration and environment determine (T, S) mesophases sequences

4. Introduction to viscosifying surfactants for EOR Cylindrical Micelles Spherical Micelles L  1 m Entanglements Low viscosity Newtonian fluid Analogy with polymer G0: Elastic modulus t: Relaxation time F = volume fraction Breakage/recombination dynamic Viscosifying surfactant as an alternative approach to SP & ASP flooding Typical surfactant flooding (S, SP, ASP) • Rheological properties of surfactant micelles in aqueous solutions

5. Introduction to viscosifying surfactants for EOR Cryo-TEM image of wormlike micelles in aqueous solution Presence of giant micelles of ≈ 5nm in diameter. A structure is visible, since they appear mostly in parallel configuration, with an inter particle distance 15 to 20nm.

6. Introduction to viscosifying surfactants for EOR Rhodia and Poweltec methodology: application to synthetic field cases Viscosity measurements Fluid propagation tests Core flood tests Viscosifying surfactant: application to field case Conclusion Contents

7. Chemistry selection Solubility Rheology Injectivity Millifluidic screening tests Viscosifying surfactant formulation RHODIA POWELTEC Coreflood Petrophysic experiments Injectivity Adsorption Oil Recovery Rhodia & Poweltec methodology: application to synthetic field cases

8. viscosity (cP) Viscosity Shear rate Rhodia & Poweltec methodology: application to synthetic field cases • Principle of high-throughput screeningfor viscosity measurements developed at Rhodia LOF • Formulation composition (surfactant & salt concentrations) are imposed thanks to syringe pumps • Formulation viscosity is determined by pressure drop measurement Surfactant solution Saturated salt sol Water Capillary (length L, radius R) • Map viscosity performance versus reservoir brine variations prior to full characterization using traditional rheometer

9. 200 T (°C) Field 3 80 90°C 150 Field 3 80°C 60 Abs. viscosity (cP) 100 Abs. viscosity (cP) 40 Field 2 Shear rate: 4 s-1 51°C 50 20 0 0.1 0.3 0.5 0.7 0.9 Salinity (g/L TDS) 32°C Field 1 0 concentration (% ) 0 0.1 0.2 0.3 0.4 0.5 w/w concentration (% ) 96 200 6 w/w 0 500 400 80 300 Abs. viscosity (cP) 60 200 Abs. viscosity (cP) 40 100 20 0 0.1 0.3 0.5 0.7 0.9 concentration (% ) w/w 0 0 0.1 0.2 0.3 0.4 0.5 concentration (% ) w/w Viscosity measurements Viscosity measurements applied to various reservoir cases Our viscosifying surfactants are salt tolerant (including divalent ions) with favorable impact of high brine concentration 9

10. Viscosity measurements Flow curve measurements in one reservoir condition Shear thinning behavior indicates that a decrease of shear rates lead to an increase of viscosity. Required surfactant concentration is thus reduced

11. Pressure sensor Syringe pump Capillary viscometer 5 cm core Pressure sensor Rhodia & Poweltec methodology: application to synthetic field cases • A miniaturized core flood test has been developed to measure fluid propagation in single-phase condition • Principle of miniaturized core flood test developed at Rhodia LOF • This miniaturized test can be used prior to full coreflood study to pre-screen performances of new surfactant formulations.

12. Patmosph.. DPcore DPcapillary Syringe pump Q = 5 mL/min Capillary Adsorption Porous media Injectivity in porous media Imposed flow rate Q = 4 mL/min Q = 3 mL/min Q = 2 mL/min Q = 1 mL/min k Rhodia & Poweltec methodology: application to synthetic field cases • An illustration of permeability measurement from (Q, DP) curve Millifluidic set-up used to measure mobility & permeability reduction

13. Rhodia & Poweltec methodology: application to synthetic field cases Background on mobility & permeability reduction • Mobility Reduction pressure drop during viscosifying surfactant slug injection at q cm3/h D P Visco. Surf Rm = pressure drop during initial brine injection at q cm3/h D P Initial brine • Permeability Reduction pressure drop during brine injectionafter viscosifying surfactant slug at q cm3/h D P Brine - After visco surf. = Rk D P Initial brine pressure drop during initial brine injection at q cm3/h Mobility Reduction is also called “Resistance Factor RF” Permeability Reduction “Residual Resistance Factor RRF”

14. Miniaturized core data Bulk rheology C2 Pressure drop viscosity DP C1 Darcy’s Law Shear rate Mean pore radius Flow rate Q Fluid propagation tests • Example of flow behavior in representative porous media (Clashach sandstone) using miniaturized core flood test Rheometer Bulk viscosity Viscosity in porous media  injection in cores impose Q and measure DP Capillary bundle model Flow in porous media match bulk rheology Good propagation of viscosifying surfactant in porous media

15. Darcy’s law 1cm Core flood tests • Representative porous media: synthetic core • Surfactants solution is injected in water saturated cores to evaluate propagation properties in porous media • Surfactants solution is injected in oil saturated cores to measure oil recovery efficiency(additional oil after water flooding)

16. Core flood tests • Porous media: clashach sandstone core • Kw = 1133 mD at 50°C – Injection brine: sea water Mobility and permeability reduction measurements in monophasic conditions Mobility Reduction values match bulk rheology: product has a good injectivity Permeability Reduction is close to Rkw=1, showing no core damage

17. Core flood tests: oil recovery efficiency Core flood sequence Results • Core - Clashach sandstone: • Porosity:  = 0.18 • Pore radius (est.): Rp = 3.4 µm • Water permeability: Kw = 1133 mD at 50°C • Residual oil saturation: Sor = 0.49 (hoil = 4.2 cp @50°C)(before injecting surfactant) Sor reduction: 12% • Fluid formulation: • Injection brine: sea water (39 g/L TDS) • Surfactant concentration: 3 g/L • Temperature: 50°C No Sor reduction with HPAM • Protocol • Saturation with oil until Swi • Water injection until Sor • Surfactant injection • Oil recovery measurement

18. Introduction to viscosifying surfactants for EOR Rhodia and Poweltec methodology: application to synthetic field cases Viscosity measurements Fluid propagation tests Core flood tests Viscosifying surfactant: application to field case Conclusion Contents

19. Reservoir conditions • Temperature: T = 51°C • Permeability: k ~ 1 – 2 D • Oil viscosity @ 51°C : h = 100 - 200 cP • Brine concentration: 6.2 g/L TDS Methodology • Select best viscosifying surfactant that matches reservoir characteristics • Compare recovery performance with polymer flooding Viscosifying surfactant: application to field case

20. Viscosifying surfactant: application to field case Absolute viscosity measurements in reservoir conditions show that same viscosity (20 cP - 10 s-1) as selected for HPAM solution (0.09%w/w) is obtained at a concentration of 0.3%w/w.

21. Viscosifying surfactant: application to field case • Thermal stability of surfactant solution Fluid formulation Surfactant concentration 0.3%w/w Temperature T = 51°C Brine concentration: 6.2 g/L TDS Oxygen content < 50 ppb Viscosity measured at 50°C at low shear rate (10s-1) Anaerobic ageing of surfactant solution shows that no viscosity loss is observed over one month- On going ageing

22. Regular polymer flooding (HPAM) experiment Viscosifying surfactant: application to field case Reservoir core plug No Sor reduction is observed after HPAM injection

23. Oil recovery experiments after polymer injection (HPAM) Viscosifying surfactant: application to field case Reservoir core plug Injection of a 0.3%w/w surfactant solution after HPAM has mobilized a significant fraction of the residual oil saturation (+16% OOIP)

24. Simulation Evaluation of viscosifying surfactant in synthetic field case • Five Spot Pattern (1 Injector 4 Producers) • Multilayer Reservoir, Strong vertical heterogeneity • Reservoir thickness = 10 m • Comparison between • Waterflood • Polymer Flood • Viscosifying Surfactant Flood

25. Simulation Evaluation of viscosifying surfactant in synthetic field case

26. Simulation Evaluation of viscosifying surfactant in synthetic field case

27. Introduction to viscosifying surfactants for EOR Rhodia and Poweltec methodology: application to synthetic field cases Viscosity measurements Fluid propagation tests Core flood tests Simulation Viscosifying surfactant: application to field case Conclusion Contents

28. Conclusion • Specific millifluidic tools have been developed to screen viscosifying surfactants from Rhodia • Following performances have been measured for viscosifying surfactants in different conditions • Viscosity at low concentration: 0.1 to 0.5% w/w • Sor reduction in coreflood DSw = 10 to 20% (hoil at least 100 cps) • High temperature / high salinity tolerance • Shear thinning / recombination dynamics (Unlike Polymer) • Limited surface facility Capex required • Perspectives • Pursue experiment on field case reservoir: adsorption measurements, additional oil recovery tests, simulation and extrapolation at pilot scale to evaluate economics