Modified Two-Phase Titration Methods to Quantify Surfactant Concentrations in Chemical-Enhanced Oil Recovery Applications |
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Authors: | Chammi Miller Badr S Bageri Tongzhou Zeng Shirish Patil Kishore K Mohanty |
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Affiliation: | 1. The University of Texas at Austin, 200 E. Dean Keeton St., Austin, TX, 78712 USA;2. King Fahd University of Petroleum & Minerals, Academic Belt Road, Dhahran 31261, Saudi Arabia |
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Abstract: | In enhanced oil recovery applications, surfactants are injected into reservoirs along with polymers and salts. The effluents eluted from lab experiments and field tests are analyzed by HPLC methods using an evaporative light scattering detector (ELSD) detector. When the surfactant concentrations are less than 100 ppm, HPLC methods are inaccurate. A novel two-phase titration method is developed where surfactant concentrations can be quantified using a calibration curve constructed with UV/vis absorption. This method can analyze surfactant concentrations 5–80 ppm where dilution eliminates any high-salinity interferences with the absorption measurements. The method is based on formation of a dye-surfactant complex and the light absorption of the complex has a linear correlation with the surfactant concentration. Anionic surfactant concentrations lower than 100 ppm can be accurately quantified using this method with methylene blue. The method was also developed for low concentrations (<50 ppm) of cationic surfactants using methyl orange and indigo carmine. The indigo carmine method can be used without the use of an organic phase. All methods are applicable at salinities up to 3 wt%. Both the methylene blue method and the methyl orange method can be used to detect zwitterionic surfactants. These methods can be used in the presence of polymers without any prior treatments. |
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Keywords: | Surfactant detection Anionic surfactant Cationic surfactant Zwitterionic surfactant Two-phase titration |
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