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Low Salinity Water Assisted by Surfactants for Enhanced Oil Recovery: Mechanistic Study and Spontaneous Imbibition Tests

Heidari, Mehdi | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54820 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ayatollahi, Shahabodin; Mahani, Hassan
  7. Abstract:
  8. Enhanced Oil Recovery (EOR) techniques have become of the main priorities of the oil industry during the high oil price era. It is interesting to note that the common method to increase production from reservoirs is the water injection method, which recovers a very low amount of oil from the oil-wet matrices due to the lack of water imbibition. Previous studies have shown that changing the wettability of rock would critically increase the oil recovery efficiency. This could be achieved by the low-salinity water injection method. In recent years, extensive studies have been conducted on this technique to evaluate its effectiveness for various types of oil reservoirs. Simultaneous injection of surfactants with low salinity has been proposed here to improve the recovery efficiency of oil-wet plugs under reservoir conditions. The main objectives of this study are to investigate the mechanism of altering the rock wettability and also to perform imbibition tests to observe these changes.The proposed mechanisms for low-salinity water are based on water-oil-rock interactions, which can be divided into two categories: low-salinity water and rock as well as low-salinity water and oil. It is already known that the water-rock effects consist of mineral dissolution, electrical double layer expansion and multiple ion exchange. On the other hand, the water-oil interface, includes interfacial tension variation, formation of micro-dispersion and osmosis phenomenon. For this purpose, in this laboratory work, an oil sample with specific properties and water with different salinities were tested without/with different types of surfactants (anionic and cationic). The main focus of these experiments is the imbibition tests to evaluate the improvement of oil production rate and recovery efficiency in the presence of the mentioned chemicals and also determine the optimal conditions to maximize the oil recovery efficiency.Based on these results, the optimal water in terms of wettability alteration was found to be two times diluted water (2DSW). Besides, the main mechanism of wettability alteration was proposed to be the change of surface charge and expansion of the electrical double layer. The results showed that the addition of CTAB to 2DSW increases the oil production, which was also increased with increasing the surfactant concentration. Adsorption tests showed that surfactant adsorption on the surface increases with decreasing the salinity of the water
  9. Keywords:
  10. Surfactants ; Wettability Alteration ; Enhanced Oil Recovery ; Low Salinity Water Flooding ; Low-Salinity Water and Surfactant Hybrid ; Imbibition Process

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