Consortium on Process in porous Media Foam experiments at high temperature And high salinity José López Maura Puerto Clarence Miller George Hirasaki 03/14/2011 1

Outline: Oil properties and oil preparation: IFT Viscosity of simulated live crude oil Salinity issues in the system: Analysis of synthetic bines Foam experiments: Surfactants used Apparatus description Mapping corefloods Foam results Foam with crude oil 2

OIL PROPERTIES AND OIL PREPARATION Part I 3 Crude oil needs to be free of contaminants and should simulate live oil

4 Oil-Brine IFT range * * John R. Fanchi Principles of Applied Reservoir Simulation 3 rd edition 2006 Elsevier ** G. Hirasaki and D.L. Zhang, "Surface Chemistry of Oil Recovery from Fractured, Oil-Wet, Carbonate Formations," SPEJ (June 2004) The crude oils must be free of surface active materials such as emulsion breaker, scale inhibitor, or rust inhibitor. A simple test to verify contamination of the oil samples is to measure the interfacial tension (IFT) of crude oil with synthetic brine ** IFT measurements to screen contaminated samples 1.65 mm V drop = cm 3 Crude 1 Crude 2 Crude 3 Crude 4

5 Iso-octane was used for making a simulated live oil, i.e., with the same viscosity at reservoir temperature, as suggested by Nelson (1983). However, adding isooctane to the dead crude oil produced precipitation of asphaltenes. Ratios of crude oil:isooctane ranging from 4:1 to 9:1 at room temperature show immediate precipitation of asphaltenes. Cyclohexane was mixed at room temperature with minimal precipitation of asphaltenes. Then this solvent was used to modify the viscosity of the dead crude oil to obtain simulated live crude oil with the same viscosity of the live crude oil. Simulated live crude oil Dead crude oil Live crude oil Adapted from Core Laboratories, Inc Page 10 of 15, File: RFL (Dallas, TX)

6 A=2.614,B= Viscosity of mixtures of dead crude oil and Cyclohexane measured in the falling sphere viscometer at °C Every experimental point is the Average of 20 measurements Precision error less than 3% Dead crude Oil Cyclohexane  = 2.8 cP The mol fraction of (Crude 1) dead crude oil to match the viscosity of live crude oil is This experiment was conducted in a sealed falling sphere viscometer. The mol fraction was calculated using a molecular weight for the crude oil of 303 kg/kg-mol Lopez et al Viscometer for Opaque, Sealed Microemulsion Samples, SPE (2009) IRS : inductive ring sensors IRS

7 Dead crude oil mass percentage 83.7%, the rest is cyclohexane. Cyclohexane 16.3% mass = 18.7% volume = 41.25% mol Results of the simulated live crude oil OilMolar mass (g/mol) Viscosity (cP) Pressure (Psia) Rice Simulated live crude oil (16.3% Cyclohexane) Simulated 2 LCO (30% Cyclohexane) Live crude oil Dead crude oil303 (*) (*) Via Benzene point depression (Core Labs) Viscosities at 114 °C

Remarks of part I 8  Crude oils are free of surface active materials such as emulsion breaker, scale inhibitor, or rust inhibitor.  Dead crude oil was mixed with cyclohexane to match viscosity of the live crude oil.

SALINITY OF BRINES USED IN THE EXPERIMENT Part II 9 Brines should be under saturated in order to prevent precipitation

The sea water has an equivalent of g of CaS0 4 per kilogram of water (*) The formation brine has an equivalent of g of CaSO 4 per kilogram of water (*) Incremental solubility is the additional CaSO 4 needed to saturate the brine 10 Incremental solubility of CaSO 4 (ScaleChem)* For synthetic formation brine Temperature of experiments 94 ° C

FOAM EXPERIMENTS Part III 11

12 Experimental set up First section Second section

Triton X-200, Alkyl Aryl poly (ethylenoxy) sulfonate C 9 H 19 (-O-C 2 H 4 ) 8.6 -SO 3 - Na + Hydrophilic surfactant 13 C IOS, Internal Olefine sulfonate Hydroxyalkane Sulfonates + Alkene Sulfonates SO 3 -Na SO 3 -Na │ │ R-CH 2 -CH 2 - CH –CH -CH 2 -CH 2 -R’ + R-CH 2 – CH-CH= CH-CH 2 -R’ │ OH Lipophilic surfactant CH 3 (CH 2 ) n (CH 2 ) 2 CH(SO 3 Na)CH(OH)(CH 2 ) 2 (CH 2 ) m CH 3 n+m=14 SURFACTANTS — (OCH 2 CH 2 ) 9.5 OH H 3 C— C —CH 2 — C — CH 3 | Triton X-100 Octylphenol ethylene oxide condensate

Initial foam experiments 14 Objective: Understand how foam performs with and without oil Using surfactant blends with aid of mapping corefloods concept

ExpNo.Crude Oil Surfactant Solution Injection rate of liquid (ft/day) Foam injection(L/G) ratio Brine Triton to IOS ratio 1 NoSW PV of foam Variable Gas 2 YesSW PV of aqueous surfactant 2.85 Foam 3 YesFB ¼ PV of aqueous surfactant 1.33 Foam 5 (*) YesFB ¼ PV of aqueous surfactant 0.74 Foam 6 Yes FB-SW ¼ PV of aqueous surfactant 0.83 Foam Gas-Brine 7 YesSW /4 PV of aqueous surfactant 1.13 Foam 15

← Sea Water Type I Desirable Surfactant propagation Foam formation Type II Undesirable Stronger foam Low oil recovery High oil recovery 16

Oil recovery comparison 17 FB-SW SW FB

Remarks from previous foam experiments Stronger foam was generated when Triton X-200 to IOS ratio was higher Stronger foam was generated at lower salinity Higher oil recoveries were obtained when injection composition was in the Type I region and far from injecting at formation brine. Foam is weaker when crude oil is present Phase behavior map (surfactant blend – brine blend) can be used to plan core flood experiments 18

New foam experiments 19 Objective: Understand how foam performs with new formulations

Hydrophilic surfactant 20 C IOS, Internal Olefine sulfonate Hydroxyalkane Sulfonates + Alkene Sulfonates SO 3 -Na SO 3 -Na │ │ R-CH 2 -CH 2 - CH –CH -CH 2 -CH 2 -R’ + R-CH 2 – CH-CH= CH-CH 2 -R’ │ OH Lipophilic surfactant CH 3 (CH 2 ) n (CH 2 ) 2 CH(SO 3 Na)CH(OH)(CH 2 ) 2 (CH 2 ) m CH 3 n+m=14 SURFACTANTS for Rice Formulation C H (-O-C 2 H 4 ) 7 -SO 3 - Na + Avanel S70

21 Type II 90°C

22 New Rice Blend Surfactant at 1% in sea water: Avanel S70 / C IOS (60/40) Foam was generated at selected test conditions in both zones, 94°C First section Second section Inlet → ←First Section ←Second section

23 Foam Experiment (Effect of liquid flow ) Surfactant Avanel S70 C IOS (60:40) at 1% mass in sea water using gas N 2 The first and the second sections were able to produce strong foam, the exception was for a flowrate of 0.25 cm 3 /min of liquid, producing only foam in the first section of the sand pack. Gas flow rate is reported in sccm. Liquid superficial velocities were in the range from 2.8 to 11.5 ft/day

24 Foam Experiment (Effect of gas flow ) Surfactant Avanel S70- C IOS (60:40) at 1% mass in sea water using gas N 2 The first and the second sections were able to produce strong foam, the exception was for a flowrate of 0.25 cm 3 /min of liquid, producing only foam in the first section of the sand pack.

25 First section Second section 1 Liquid PV = cm 3 /min Case: Cutting the liquid flow rate (verification of importance of liquid rate)

26 Effluent of the foam generated with the New Rice Blend.

Remarks from new foam experiments New Rice Blend produced strong foam at 1% mass in sea water through silica sand. 27

Acknowledgements Consortium on Process in porous Media PEMEX Roberto Rocca Fundation ITESM 28

End 29

Backup slides 30

Conditions Experiment 7 Initial residual oil (20%) Absolute permeability darcy K W,RO =35.0 darcy (rel perm 0.24) K O,IW =86.73 darcy (rel perm 0.65) 31

Oil Recovery Exp 6 Experiment 6 32

Experiment 6 33

Experiment 6 34

Experiment 6 35

36 G realGLdP/dzG/(G+L)P gage cm 3 /minsccmcm 3 /minpsi/ft psi dP/dz dP/dz Injection Volume quality

37 P > 2 atm