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Surfactant flooding is an [[Enhanced oil recovery (EOR)|Enhanced Oil Recovery]] technique in which the mobility of residual oil in the reservoir is increased by reducing the [[Interfacial tension|Interfacial Tension]] (IFT) between the injected fluid and the reservoir oil.<ref name=":0">Ali, S.M. Farouq, and S. Thomas. "The Promise And Problems of Enhanced Oil Recovery Methods." ''J Can Pet Technol'' 35 (1996): No Pagination Specified. doi: https://doi.org/10.2118/96-07-07</ref>
Surfactant flooding is an [[Enhanced oil recovery (EOR)|Enhanced Oil Recovery]] technique in which the mobility of residual oil in the reservoir is increased by reducing the [[Interfacial tension|Interfacial Tension]] (IFT) between the injected fluid and the reservoir oil.<ref name=":0">Ali, S.M. Farouq, and S. Thomas. "The Promise And Problems of Enhanced Oil Recovery Methods." ''J Can Pet Technol'' 35 (1996). doi: https://doi.org/10.2118/96-07-07</ref>
<br />[[File:Schematic-of-a-surfactant-based-flooding-process-applied-to-a-petroleum-field.png|thumb|Schematic of a surfactant-based flooding process applied to a petroleum field.  <ref>Gurgel, Alexandre & Moura, Maria & Castro, Tereza & Barros Neto, E. & Dantas Neto, Afonso. (2008). A review on chemical flooding methods applied in enhanced oil recovery. Braz. J. Pet. Gas. 2. [https://www.researchgate.net/publication/267805055_A_review_on_chemical_flooding_methods_applied_in_enhanced_oil_recovery 10.5419/bjpg.v2i2.53.] </ref>|alt=|466x466px|left]]
<br />[[File:Schematic-of-a-surfactant-based-flooding-process-applied-to-a-petroleum-field.png|thumb|Schematic of a surfactant-based flooding process applied to a petroleum field.  <ref>Gurgel, Alexandre & Moura, Maria & Castro, Tereza & Barros Neto, E. & Dantas Neto, Afonso. (2008). A review on chemical flooding methods applied in enhanced oil recovery. Braz. J. Pet. Gas. 2. [https://www.researchgate.net/publication/267805055_A_review_on_chemical_flooding_methods_applied_in_enhanced_oil_recovery 10.5419/bjpg.v2i2.53.] </ref>|alt=|466x466px|left]]


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==Overview of surfactant flooding==
==Overview==


Surfactant flooding is a chemical Enhanced Oil Recovery technique (cEOR) in which a small amount of surfactant (0.3-1.0 volume%) is mixed with the injected fluid (water) to sweep the reservoir oil<ref name=":1">Ali, H. (2016, November 13). Surfactant flooding reservoir simulation. Retrieved March 16, 2021, from https://www.slideshare.net/heshammokhtar2031/surfactant-flooding-reservoir-simulation</ref>. Surfactants are blended with co-surfactants which acts as active agents to enhance the properties of surfactant solution and helps to sustain optimal conditions with respect to pressure, temperature and salinity.
It is a chemical Enhanced Oil Recovery technique (cEOR) in which a small amount of surfactant (0.3-1.0 volume%) is mixed with the injected fluid (water) to sweep the reservoir oil<ref name=":1">Ali, H. (2016, November 13). Surfactant flooding reservoir simulation. Retrieved March 16, 2021, from https://www.slideshare.net/heshammokhtar2031/surfactant-flooding-reservoir-simulation</ref>. Surfactants are blended with co-surfactants which acts as active agents to enhance the properties of surfactant solution and helps to sustain optimal conditions with respect to pressure, temperature and salinity.


In [[Enhanced oil recovery (EOR)|EOR techniques]] a fluid or gas is injected in the reservoir to displace residual crude oil from the reservoir. In this chemical Enhance Oil Recovery (cEOR) technique, surfactants along with aqueous solution are injected forming a micro emulsion<ref>Mai, A., Bryan, J., Goodarzi, N., & Kantzas, A. (2009). Insights into non-thermal recovery of heavy oil. ''Journal of Canadian Petroleum Technology,'' ''48''(03), 27-35. [[doi:10.2118/09-03-27]]</ref>. These injected fluids interact with the reservoir rock and oil trapped in pores resulting in oil production by controlling the [[Phase behavior of pure fluids|phase behavior]] properties in the oil reservoir and by reducing  residual oil in the pore spaces of the matrix rocks.
The presence of surfactants also improves the wettability (oil-wet to water-wet) of reservoir rock to enhance the recovery of oil. Surfactants also improve the recovery of residual oil through other mechanisms like micro-emulsification of trapped residual oil and by changing the interfacial rheological properties.<ref>Mai, A. & Bryan, J. & Goodarzi, N. & Kantzas, A.. (2009). Insights Into Non-Thermal Recovery of Heavy Oil. Journal of Canadian Petroleum Technology - J CAN PETROL TECHNOL. [https://www.researchgate.net/publication/250093184_Insights_Into_Non-Thermal_Recovery_of_Heavy_Oil 48. 27-35. 10.2118/09-03-27]. </ref>Sometimes, the surfactants and co-surfactants, along with other components of the aqueous solution form a micro emulsion<ref>Mai, A., Bryan, J., Goodarzi, N., & Kantzas, A. (2009). Insights into non-thermal recovery of heavy oil. ''Journal of Canadian Petroleum Technology,'' ''48''(03), 27-35. [[doi:10.2118/09-03-27]]</ref>.  


The presence of surfactants also improves the wettability (oil-wet to water-wet) of reservoir rock to enhance the recovery of oil. Surfactants also improve the recovery of residual oil through other mechanisms like micro-emulsification of trapped residual oil and by changing the interfacial rheological properties.<ref>Mai, A. & Bryan, J. & Goodarzi, N. & Kantzas, A.. (2009). Insights Into Non-Thermal Recovery of Heavy Oil. Journal of Canadian Petroleum Technology - J CAN PETROL TECHNOL. [https://www.researchgate.net/publication/250093184_Insights_Into_Non-Thermal_Recovery_of_Heavy_Oil 48. 27-35. 10.2118/09-03-27]. </ref>
In primary and secondary recovery less than 50% of the oil can be produced and the residual oil gets trapped in the pores due to capillary forces<ref>Selby, R., Alikhan, A., & Ali, S. F. (1989). Potential of non-thermal methods for heavy oil recovery. ''Journal of Canadian Petroleum Technology,'' ''28''(04). [[doi:10.2118/89-04-02]]</ref>. Therefore, in chemical enhance oil recovery (cEOR), surfactant solution is injected into the reservoir which reduces the capillary forces by greatly lowering the interfacial tension<ref name=":0" />.
 
In primary and secondary recovery only one third of oil can be produced and the residual oil gets trapped in the pores due to capillary forces and viscous forces<ref>Selby, R., Alikhan, A., & Ali, S. F. (1989). Potential of non-thermal methods for heavy oil recovery. ''Journal of Canadian Petroleum Technology,'' ''28''(04). [[doi:10.2118/89-04-02]]</ref>. Therefore, in chemical enhance oil recovery (cEOR), surfactant solution is injected into the reservoir which increases the capillary number by lowering the interfacial tension or by achieving Ultralow [[Interfacial tension|Interfacial Tension]] and its range should be reduced to 0.001mN/m. This chemical EOR technique has been reviewed recently<ref name=":0" />.


==Surfactants types used==
==Surfactants types used==
The surfactants are primarily divided into four categories<ref name=":1" />
The surfactants are primarily divided into four types<ref name=":1" />


*Cationic surfactant
*Cationic surfactant
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===Micelle formation in surfactant flooding===
===Micelle formation in surfactant flooding===
Micro emulsions are formed in surfactant flooding between water and oil as two immiscible phases and by lowering interfacial tension and viscosity which increases mobility of oil<ref>Cristina, V., Castro Dantas, T. N., & Dantas Neto, A. A. (2012). The use Of Microemusion systems in oil industry. ''Microemulsions - An Introduction to Properties and Applications''. [[doi:10.5772/36803]]</ref>.
Micro emulsions are formed in surfactant flooding between water and oil as the two immiscible phases resulting in drastically reduced IFT which mobilizes the trapped residual oil<ref>Cristina, V., Castro Dantas, T. N., & Dantas Neto, A. A. (2012). The use Of Microemusion systems in oil industry. ''Microemulsions - An Introduction to Properties and Applications''. [[doi:10.5772/36803]]</ref>.


===Surfactant adsorption===
===Surfactant adsorption===
Adsorption process occurs when the surfactant accumulates on the surface of reservoir rock forming micelles  and surface charge at the solid and liquid interface. The surfactant concentration must not exceed the value of CMC. Surfactant properties alter considerably based on the critical micelle concentration (CMC). Each surfactant has their unique CMC value based on temperature, salinity and hydrophobic chain length. CMC value for ionic surfactant decreases by factor of 2 and by factor of 3 for non-ionic surfactant<ref>Kamal, M. S., Hussein, I. A., & Sultan, A. S. (2017). Review on Surfactant Flooding: Phase behavior, RETENTION, Ift, and field applications. ''Energy & Fuels,'' ''31''(8), 7701-7720. [[doi:10.1021/acs.energyfuels.7b00353]]</ref>. To obtain lower IFT and good foam stability the surfactant concertation should be greater than the CMC value.
Adsorption process occurs when the surfactant molecules attach on the surface of reservoir rock. This hinders the propagation of surfactant and increases the amount of surfactant that must be injected to maintain the low IFT throughout the life of the flood<ref>Kamal, M. S., Hussein, I. A., & Sultan, A. S. (2017). Review on Surfactant Flooding: Phase behavior, RETENTION, Ift, and field applications. ''Energy & Fuels,'' ''31''(8), 7701-7720. [[doi:10.1021/acs.energyfuels.7b00353]]</ref>.  


==Reservoir compatibility==
==Reservoir compatibility==
Carbonate reservoirs are generally suitable for cEOR techniques. However, it is not suitable for surfactant flooding since carbonate reservoir are composed of calcite (CaC03), magnesite (MgCO3), anhydrites (CaSO4) etc. which have high conductivity and a  low permeability matrix and mostly has oil wet/mixed wet conditions. Sandstone Reservoirs are homogenous and are more suitable of cEOR.    
Carbonate reservoirs are generally not suitable for surfactant flooding since carbonate reservoir are composed of calcite (CaC03), magnesite (MgCO3), anhydrites (CaSO4) etc. which have a  low permeability matrix and mostly has oil wet or mixed wet conditions along with high concentration of divalent ions in their connate water. Sandstone Reservoirs are homogeneous and are more suitable of cEOR.    


==Future challenges==
==Future challenges==


*High temperature, High Salinity, fractured Carbonate reservoirs.
*High temperature, High Salinity, fractured Carbonate reservoirs.
*Low temperature and low salinity conditions are optimal, but sulphonate based surfactants can be used for high temperature and low salinity conditions.
*Low temperature and low salinity conditions are optimal, but sulfonate surfactants can be used for high temperature and low salinity conditions.
*High Adsorption and precipitation of surfactant is challenging for high temperature and high salinity sandstone reservoirs.
*High Adsorption and precipitation of surfactant is challenging for high salinity sandstone reservoirs.


==References==
==References==
{{reflist}}
{{reflist}}
<references />
<references />

Latest revision as of 00:16, 11 April 2021

Surfactant flooding is an Enhanced Oil Recovery technique in which the mobility of residual oil in the reservoir is increased by reducing the Interfacial Tension (IFT) between the injected fluid and the reservoir oil.[1]


Schematic of a surfactant-based flooding process applied to a petroleum field.  [2]











Overview

It is a chemical Enhanced Oil Recovery technique (cEOR) in which a small amount of surfactant (0.3-1.0 volume%) is mixed with the injected fluid (water) to sweep the reservoir oil[3]. Surfactants are blended with co-surfactants which acts as active agents to enhance the properties of surfactant solution and helps to sustain optimal conditions with respect to pressure, temperature and salinity.

The presence of surfactants also improves the wettability (oil-wet to water-wet) of reservoir rock to enhance the recovery of oil. Surfactants also improve the recovery of residual oil through other mechanisms like micro-emulsification of trapped residual oil and by changing the interfacial rheological properties.[4]Sometimes, the surfactants and co-surfactants, along with other components of the aqueous solution form a micro emulsion[5].

In primary and secondary recovery less than 50% of the oil can be produced and the residual oil gets trapped in the pores due to capillary forces[6]. Therefore, in chemical enhance oil recovery (cEOR), surfactant solution is injected into the reservoir which reduces the capillary forces by greatly lowering the interfacial tension[1].

Surfactants types used

The surfactants are primarily divided into four types[3]

  • Cationic surfactant
  • Anionic surfactant
  • Non-ionic surfactant
  • Amphoteric
Molecular structure and classification of various surfactant molecules[7]


Mechanisms of surfactant flooding

Micelle formation in surfactant flooding

Micro emulsions are formed in surfactant flooding between water and oil as the two immiscible phases resulting in drastically reduced IFT which mobilizes the trapped residual oil[8].

Surfactant adsorption

Adsorption process occurs when the surfactant molecules attach on the surface of reservoir rock. This hinders the propagation of surfactant and increases the amount of surfactant that must be injected to maintain the low IFT throughout the life of the flood[9].

Reservoir compatibility

Carbonate reservoirs are generally not suitable for surfactant flooding since carbonate reservoir are composed of calcite (CaC03), magnesite (MgCO3), anhydrites (CaSO4) etc. which have a  low permeability matrix and mostly has oil wet or mixed wet conditions along with high concentration of divalent ions in their connate water. Sandstone Reservoirs are homogeneous and are more suitable of cEOR.  

Future challenges

  • High temperature, High Salinity, fractured Carbonate reservoirs.
  • Low temperature and low salinity conditions are optimal, but sulfonate surfactants can be used for high temperature and low salinity conditions.
  • High Adsorption and precipitation of surfactant is challenging for high salinity sandstone reservoirs.

References

  1. 1.0 1.1 Ali, S.M. Farouq, and S. Thomas. "The Promise And Problems of Enhanced Oil Recovery Methods." J Can Pet Technol 35 (1996). doi: https://doi.org/10.2118/96-07-07
  2. Gurgel, Alexandre & Moura, Maria & Castro, Tereza & Barros Neto, E. & Dantas Neto, Afonso. (2008). A review on chemical flooding methods applied in enhanced oil recovery. Braz. J. Pet. Gas. 2. 10.5419/bjpg.v2i2.53.
  3. 3.0 3.1 Ali, H. (2016, November 13). Surfactant flooding reservoir simulation. Retrieved March 16, 2021, from https://www.slideshare.net/heshammokhtar2031/surfactant-flooding-reservoir-simulation
  4. Mai, A. & Bryan, J. & Goodarzi, N. & Kantzas, A.. (2009). Insights Into Non-Thermal Recovery of Heavy Oil. Journal of Canadian Petroleum Technology - J CAN PETROL TECHNOL. 48. 27-35. 10.2118/09-03-27.
  5. Mai, A., Bryan, J., Goodarzi, N., & Kantzas, A. (2009). Insights into non-thermal recovery of heavy oil. Journal of Canadian Petroleum Technology, 48(03), 27-35. doi:10.2118/09-03-27
  6. Selby, R., Alikhan, A., & Ali, S. F. (1989). Potential of non-thermal methods for heavy oil recovery. Journal of Canadian Petroleum Technology, 28(04). doi:10.2118/89-04-02
  7. Nakama, Y. (2017, March 10). Surfactants. Retrieved March 12, 2021, from https://www.sciencedirect.com/science/article/pii/B978012802005000015X?via%3Dihub
  8. Cristina, V., Castro Dantas, T. N., & Dantas Neto, A. A. (2012). The use Of Microemusion systems in oil industry. Microemulsions - An Introduction to Properties and Applications. doi:10.5772/36803
  9. Kamal, M. S., Hussein, I. A., & Sultan, A. S. (2017). Review on Surfactant Flooding: Phase behavior, RETENTION, Ift, and field applications. Energy & Fuels, 31(8), 7701-7720. doi:10.1021/acs.energyfuels.7b00353