Zeta potential changes at mineralbrine and oil-brine interfaces control improved oil recovery during smart waterflooding

Transcription

1 Zeta potential changes at mineralbrine and oil-brine interfaces control improved oil recovery during smart waterflooding Matthew Jackson Dawoud Al-Mahrouqi, Shuai Li Department of Earth Science and Engineering, Imperial College London

2 Low salinity ( smart ) waterflooding successes In sandstones Imperial College London Example from RezaeiDoust et al. (211) reproduced in Jackson et al., Fuel, (216)

3 Low salinity ( smart ) waterflooding successes In carbonates Imperial College London (Yousef et al., 21)

4 All looking rosy but Imperial College London Example from Nasralla and Nasr-El-Din (214) reproduced in Jackson et al., Fuel, (216)

5 All looking rosy and 6 Cumulative oil recovery % FMB % incremental 1dFMB PVs injected Imperial College London (Austad et al., 211)

6 Smart waterflooding: what we don t know Why it doesn t always work and/or is not always repeatable How to identify candidate reservoirs without conducting numerous costly core-flooding experiments How to predict the optimum modified (controlled) injection brine composition Imperial College London Jackson et al., Fuel, (216)

7 Why zeta potential? Measure of electrical charge at an interface (mineral-brine, oil-brine, gas-brine etc..) Controls the electrostatic interactions between mineral surfaces and polar species in aqueous and non-aqueous solution Probes mineral surface so sensitive to wetting state Mechanisms invoked to explain improved recovery during smart waterflooding cause changes in zeta potential at mineral-brine interface Concentration of potential determining ions (PDIs) Ion exchange on mineral surfaces Double layer expansion Imperial College London Jackson et al., Fuel, (216)

8 Zeta potential at mineral-brine interfaces Imperial College London Glover and Jackson (21)

9 Sandstones and potential determining ions (PDIs) Zeta potential depends on ph for metal oxides (protonation and deprotonation reactions at mineral surface) Zeta potential also depends on adsorption of salt species onto mineral surfaces (e.g. Ca2+, Mg2+) Indifferent ions do not directly interact with surface Imperial College London Ishido and Mizutani, 1981

10 Zeta potential and double layer expansion Generally assumed zeta potential at mineral-brine interfaces increases in magnitude during dilution Zeta potential also depends on adsorption of salt species onto mineral surfaces (e.g. Ca2+, Mg2+) Imperial College London Example from Vinogradov et al. (21) reproduced in Jackson et al., Fuel, (216)

11 Carbonates and potential determining ions (PDIs) Zeta potential depends on ph in unbuffered experiments (pca allowed to vary) Zeta potential constant in buffered experiments (pca fixed) Proton is not a PDI for the carbonate mineral surface Imperial College London Foxall et al., 1979

12 Carbonates and potential determining ions (PDIs) Zeta potential (mv) Ca Mg SO4 ppdi FMB SW,5 1 1,5 2 2,5 3 3, Identical behavior of Ca and Mg within experimental error Sensitivity to SO4 much lower (not a PDI?) AlRoudhan et al., Col. Surf. A, 216

13 Carbonates and potential determining ions (PDIs) 4 Zeta potential (mv) pca,5 1 1,5 2 2,5 3 3,5.5M 2M.5M Similar to 1x dilute seawater Similar to typical formation brine Increasing ionic strength Sensitivity to pca and pmg decreases with increasing total ionic strength AlRoudhan et al., Col. Surf. A, 216

14 Carbonates and potential determining ions (PDIs) Estaillades NaCl =.5 M NaCl = 2 M Zeta Potential (mv) Ketton and Portland NaCl-EQ experiments -8 Estaillades -1 Ketton Portland pca Different carbonates exhibit different behaviour AlMahrouqi et al., Adv. Col. Int. Sci., 217

15 Measurement of zeta potential: The zetameter Measurement of zeta potential is routine in materials science Off-the-shelf commercial equipment available BUT. Require powdered samples Limited range of pressure/temperature/ionic strength Only one fluid phase present IN NATURE Intact rocks High P/T/I Oil + water Imperial College London Example from Malvern

16 Experimental setup Pump V 1 Oil reservoir Metering valve V 4 V 3 V 2 Pressure transducer NI Data Acquisition P 1 System P 2 Coiled flowline O O V 6 B Core holder B Thermocouple V 5 C = V P j= = w Sampling ε wς µ σ F rw Confining pressure pump Sampling Oven M Manometer Vinogradov et al., 21

17 Typical experimental results 6 -,79 4 Pressure, kpa ,84 Time, s ,89 -,94 Voltage, mv ,99 Synthetic Formation Brine (2M, c. 25,ppm) AlRoudhan et al., Zeta Potential of Intact Natural Limestone: Impact of Potential-Determining Ions, Col Surf A 216

18 Zeta potential in brine-saturated (water-wet) carbonates and sandstones Zeta potential (mv) Sst Carbonates FMB to dilute seawater

19 Link between zeta potential and wettability 9 Change in zeta potential after aging (mv) ,8,6,4, Amott Water Wetting Index (-) Increasing oil wetness Modified from Jackson et al., Sci. Rep. (216)

20 Link between zeta potential and wettability 9 Change in zeta potential after aging (mv) Water wet Water wet Water wet ,8 Increasing oil wetness,6,4 Amott Water Wetting Index (-),2 Modified from Jackson et al., Sci. Rep. (216)

21 Link between zeta potential and wettability 9 Change in zeta potential after aging (mv) ,8,6,4,2-3 Oil wet - - Oil wet - Water wet Water -5 Oil Water wet Oil wet Water wet -7 Amott Water Wetting Index (-) Increasing oil wetness Modified from Jackson et al., Sci. Rep. (216)

22 Link between zeta potential and wettability 9 Change in zeta potential after aging (mv) ,8 Increasing oil wetness,6,4 Trend indicates negative zeta potential at oil-brine interface Amott Water Wetting Index (-),2 Modified from Jackson et al., Sci. Rep. (216)

23 Link between zeta potential and wettability Change in zeta potential after aging (mv) ,8 Increasing oil wetness Modified from Jackson et al., Sci. Rep. (216) 1 + Oil wet Oil wet Water wet Water + + Oil Water wet Oil wet Water wet,6,4 Trend indicates negative zeta potential at oil-brine interface Amott Water Wetting Index (-),2

24 Link between zeta potential and wettability 9 Change in zeta potential after aging (mv) Increasing oil wetness Trend indicates positive zeta potential at oil-brine interface,8,6,4 Trend indicates negative zeta potential at oil-brine interface Amott Water Wetting Index (-),2 Modified from Jackson et al., Sci. Rep. (216)

25 Link between zeta potential and wettability 9 Change in zeta potential after aging (mv) Increasing oil wetness Trend indicates positive zeta potential at oil-brine interface,8,6,4 Trend indicates negative zeta potential at oil-brine interface Amott Water Wetting Index (-) Sandstone,2 Modified from Jackson et al., Sci. Rep. (216)

26 Link between zeta potential and EOR in carbonates: Conventional LSW with ve oil 6 Oil D Cumulative oil recovery (%) SPM1 ζ F SPM2 ζ i(sw) Cumulative incremental oil recovery FMB SW 2dSW SPM3 ζ i(2dsw) Pore volume injected, ml Jackson et al., Zeta potential in oil-water-carbonate systems and its impact on oil recovery during CSW, Scientific Reports 216

27 Link between zeta potential and EOR in carbonates: Conventional LSW with +ve oil Oil A 8 Cumulative oil recovery (%) SPM1 ζ F SPM2 ζ i(sw) FMB SW 2dSW SPM3 ζ i(2dsw) Pore volume injected, ml Jackson et al., Zeta potential in oil-water-carbonate systems and its impact on oil recovery during CSW, Scientific Reports 216

28 Link between zeta potential and EOR in carbonates: Inverted LSW with +ve oil Cumulative oil recovery (%) SPM1 ζ F SPM2 ζ i(sw) Cumulative incremental oil recovery 2dSW SW FMB Pore volume injected, ml SPM3 ζ i(fmb) Improved recovery with oil A by increasing salinity! Change in zeta potential is key, not change in salinity Jackson et al., 216

29 Link between zeta potential and EOR in sandstones Oil Recovery, %OOIP Oil Recovery, %OOIP Oil D FMB2 SW3d Pore Volume Oil A SW3d FMB Pore Volume Pressure difference (psi) &ph Pressure difference (psi) &ph Incremental oil recovery during conventional CSW with ve oil is around 5.25% OOIP Incremental oil recovery during inverted CSW with +ve oil is around 3.25% OOIP

30 Correlation between IOR and change in zeta potential all experiments IOR (%) ζ ζ ζ n = ζ ζ FMB Sw= 1 FMB Sw= 1 CSW Sw= 1 FMB Sw= 1 Sor Normalize the change in zeta potential resulting from CSW by the change in zeta potential corresponding to wettability alteration Jackson et al., Sci. Rep. (216)

31 Zeta potential of oil droplets Hexadecane droplets in.4 mm NaClO4 Suggested that hydroxide ions charge and stabilize droplets But emulsions become unstable > 5mM salt (how measure zeta potential?) (from Beattie and Djerdev, 24)

32 Zeta potential and CSW If the oil-water interface has a negative zeta potential: IOR observed by CSW to produce a more negative zeta potential on mineral surfaces conventional approach of diluting formation brine and/or seawater is successful If the oil-water interface has a positive zeta potential: IOR observed by CSW to produce a more positive zeta potential on mineral surfaces increasing the concentration of Ca or Mg ions may be successful in carbonates Studies that have failed to observe improved recovery using the conventional (dilution) approach to CSW may have been dealing with a positive zeta potential at the oilwater interface