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Salt Tolerant Synthetic Polymers Effects on adsorption and retention

Salt Tolerant Synthetic Polymers Effects on adsorption and retention. Masoud Rashidi Sigmund Sandvik Anne Marit Blokhus Arne Skauge Presented by Ketil Djurhuus. IEA Collaborative Project on EOR 30th Annual Workshop and Symposium 21-23 September, Canberra, Australia. Outline.

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Salt Tolerant Synthetic Polymers Effects on adsorption and retention

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  1. Salt Tolerant Synthetic PolymersEffects on adsorption and retention Masoud Rashidi Sigmund Sandvik Anne Marit Blokhus Arne Skauge Presented by Ketil Djurhuus IEA Collaborative Project on EOR30th Annual Workshop and Symposium 21-23 September, Canberra, Australia

  2. Outline • Introduction and motivation • Materials and experiments • Static and dynamic retention • Practical applications • Conclusions

  3. Why polymer flooding? • Improve area sweep • Reduce viscous fingering Before polymer floodingAfter polymer flooding High mobility ratio Low mobility ratio

  4. Limitations of conventional polymers 20 Salinity (wt.%) 10 5 Xanthan Temperature (°C) HPAM 0 50 100 150

  5. Effects of polymer adsorption and retention • Polymers accumulate adsorb at the solid/liquid interface. • Polymer injection reduces permeability due to retention of polymer by adsorption and mechanical entrapment. • Loss of polymer due to retention causes lower viscosity of fluid.

  6. Materials • HPAM little salt tolerant • Sulfonated copolymers have improved solution properties • Sulfonation improves salt tolerance compared to carboxylates • Sulfonated polymers are less prone to precipitation Hydrolyzed polyacrylamide Sulfonated polyacrylamide

  7. Experimental plan Varying sulfonation degree Molecular weight = 8 MDalton 1 Molecular weight = 6 MDalton Varying molecular weight Sulfonation degree = 25 mole%

  8. Experiments • Static adsorption • Two different minerals e.g. kaolinite and silica • Constant solid/liquid ratio to avoid flocculation. • Dynamic retention • Berea outcrop sandstone • Injection of two pore volumes polymer with known concentration followed by 3 pore volumes solvent • Tracer injected along with the polymer to detect any difference in flow pattern

  9. Static adsorption Adsorption isotherm on kaolinite. SD= 13% Mw = 8 MDalton S/L= 0.005, T = 20C, Salinity = 5 wt% NaCl

  10. Static adsorption: Effect of sulfonation Mw = 8 MDalton S/L= 0.005, T = 20C

  11. Static adsorption: Effect of molecular weight Sulfonation degree = 25% S/L= 0.005, T = 20C

  12. Dynamic retention Dynamic retention profile on a Berea core. SD= 25% Mw = 12 MDalton. T = 20C. Salinity = SSW

  13. Dynamic retention: Effect of sulfonation Mw = 8 MDalton T = 20C

  14. Dynamic retention: Effect of molecular weight Sulfonation degree = 25% T = 20C

  15. Practical applications Both retention and viscosity are important for practical use of polymers

  16. Conclusions • Sulfonated polyacrylamide polymers have considerably lower levels of both adsorption and retention than corresponding carboxylates • Increasing the sulfonation degree reduces levels of both static adsorption and dynamic retention • Static adsorption show an increasing trend with respect to increasing molecular weight • Dynamic retention, however, show a decreasing trend with respect to increasing molecular weight

  17. Conclusions • At equal ionic strengths the presence of divalent cations leads to increased adsorption and retention • Viscosity is maintained even at high sulfonation degree,but there is a substantial decrease in adsorption and retention • This combination of factors makes samples with a high degree of sulfonation especially interesting for polymer flooding in high salinity reservoirs.

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