Modeling of Wettability Alteration During Enhanced Oil Recovery by Surfactants

Aliabadian, Ehsan | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46799 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghazanfari, Mohammad Hossein; Ayatollahi, Shahaboddin
  7. Abstract:
  8. There are considerable investigations on wettability alteration in carbonate reservoirs in recent years. The presence of ions including Ca, Si, Al etc in natural carbonate rocks and also the presence of various fatty acids, resins, asphaltenes etc in crude oil makes it difficult to understand the complex mechanism of wettability alteration by using surfactants. Furthermore there is still a conspicuous lack of dynamic wettability alteration model to demonstrate the dynamic behavior of cationic surfactants during wettability alteration. It is also widely accepted that cationic surfactants have substantial impact on changing the wettability of strongly oil-wet matrixes to a more water-wet condition through forming ion-pair with carboxylate anions. In this work, calcite pellets and model oil were utilized as carbonate surface and oil respectively in wettability alteration experiments. Using calcite pellets enables us to reduce the amount of adsorption of cationic surfactant to a negligible amount. By using two phase titration method and static contact angle measurement techniques, surfactant concentration and contact angle as a function of time were evaluated. Two types of cationic surfactants, C14TAB and C16TAB, were used in the tests to determine their ability in removing the adsorbed stearic acids from the calcite surface. The results indicate that as the length of hydrophobic tail of cationic surfactant increases, the rate of wettability alteration process decreases and also the monomers of cationic surfactants have the most effect on wettability alteration. Furthermore, it has been found that desorption of stearic acid obeys a pseudo second order kinetic model with a reasonable accuracy. As a result, a new dynamic wettability alteration model, whose results matched well with the experimental data, has been proposed. We also compare the behavior of natural carbonate rocks and calcite pellets. The results of this work can be helpful for better understanding of dynamic behavior of wettability alteration during chemical injections, which might also be useful in improving the mathematical models of chemical transport in porous media
  9. Keywords:
  10. Cationic Surfactant ; Wettability Alteration ; Two-Phase Titration ; Second Order Desorption Model

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