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Experimental Investigation of Stability Analysis and Applicability of Foam Flooding for Enhanced Oil Recovery

Shokrollahi, Amin | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44841 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghazanfari, Mohammad Hossein; Badakhshan, Amir
  7. Abstract:
  8. One of the suitable methods in EOR processes is miscible and immiscible gas injection. By gas injection, it is possible to replace all the oil, which is in contact with the gas. However, reservoir heterogeneity, low density, and low viscosity of gas result in problems such as gravity segregation, and fingering and consequently the gas reach the production well without any significant contact with reservoir oil. A way to deal with this problem is gas injection in the form of foam. In fact, gas injection in this manner increases the oil production by decreasing gas mobility and the negative effects of reservoir heterogeneity on gas displacement. Foam stability has a key role on the efficiency of foam injection process. Salinity variation and presence of salts are factors that affect the stability of the injected foam to the reservoir. Moreover, the existence of alkaline, which is utilized to decrease the surfactant absorption on the rock surface in chemical EOR processes, is effective for foam stability and consequently on the ultimate oil recovery. The performed experiments in this study are classified in two classes. In the first part, the foam stability in different conditions such as presence of different types of surfactants, gas type (nitrogen and carbon dioxide), presence of salts, and alkaline is investigated. In the next part, by using the best surfactants that have resulted in the most stable foams, the core flood testsare carried out. The foam injection tests are performed as Surfactant Alternating Gas injection (SAG). In these tests, the effects of types of surfactant and the SAG ratio on oil recoverywas studied. In addition, a series of tests are performed in order to compare Water Alternating Gas injection (WAG) recovery and Surfactant Alternating Gas injection (SAG) recovery. It should be mentioned that the entire tests are performed on sandstone core. The results of the stability tests are indicative of complex behavior of developed foams in different conditions. Foams developed by nitrogen are much more stables than foams developed by carbon dioxide. According to the acquired results, the monovalent NaCl salt always results in decreasing the stability of produced foams by ionic surfactants, but divalent MgCl2 salt, result in an upsurge in the stability of the foam produced by anionic SDS surfactant and decrease the foam stability by increasing the concentration. MgCl2 always wane the foam stability produced by cationic CTAB surfactant. The effects of salt and alkaline on the stability of foam that produce by nonionic surfactant Triton X-100 are negligible. Due to the different types of ion present in various alkaline, the presence of monovalent and divalent alkaline exhibits different behaviors on the developed foams. The overall results of core flood tests suggest the superiority of Surfactant Alternating Gas injection (SAG) in comparison with Water Alternating Gas injection (WAG). In addition, in SAG injection, a decrease in SAG ratio, increase the oil recovery. Ultimately, the validity of the acquired data from experiments is investigated by Leverage method
  9. Keywords:
  10. Foam ; Surfactants ; Foam Stability ; Core Flooding ; Enhanced Oil Recovery ; Alkaline

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