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Study of Industrial Wastewater as Low-Salinity Water for Enhanced Oil Recovery

Mohammadi, Hossein | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56878 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ayatollahi, Shahaboddin; Mahani, Hassan
  7. Abstract:
  8. Considering the water tensions, especially in the Middle East, water resources for the implementation of water-based EOR methods are shown to be critically limited. Water sources such as industrial wastewater hold great potential to be used for this purpose due to their significant available volume and the need for their disposal because of environmental regulations. In this research, the potential of injecting industrial wastewater, as low-salinity water, in an Iranian carbonated oil reservoir has been thoroughly investigated by conducting core-scale experiments. In this regard, we also developed a guideline for designing various types of experiments to use this "unconventional" injection water source for low-salinity EOR. The most important wastewater properties are total dissolved solids or salinity (TDS), total suspended solids (TSS), chemical and biochemical oxygen demand, and microbial activities that must be investigated. Specifically, the use of sugarcane factory wastewater as low-salinity water is investigated due to its significant volume. The most important part of this research is the experiments of spontaneous imbibition and coreflooding, which were performed at the temperature of the reservoir and were complemented by other tests related to the reduction of injectivity (or permeability) and the possibility of destructive activity of bacteria. Various types of brines were used in the experiments, including industrial wastewater, Persian Gulf seawater, saline formation water, and mixed water. The results show that this industrial wastewater can reduce the interfacial tension (IFT) between water and oil and change the wettability of rock towards a more water-wetting state. The use of this wastewater in the secondary and tertiary injection scenarios also led to the production of 57.2% of oil in place (OIP) and an additional 8.3% over the injection of saline formation water in the reservoir, part of which is after applying a period of “soaking”and ensuring that the slow process of wettability alteration is completed. These results indicate the very good potential of the sugarcane waste waterin the EOR process. Considering the higher probability of the formation of a viscous (sticky) emulsion in the imbibition tests and that a brine salinity close to twice diluted seawater has an optimal salinity, it is possible to use this industrial wastewater to reduce the salinity of seawater and bringing it to twice diluted salinity, without applying expensive desalination operations. This can help prevent the formation of viscous emulsion. The results of using the mixed water of seawater and industrial wastewater in imbibition experiments under secondary and tertiary scenarios respectively led to the production of 48.5% of OIP and 16.2% additional oil after core exposure to FW. The coreflooding tests showed that the use of mixed water under the secondary and tertiary scenarios, respectively, leads to 62.2% OIP recovery factor and 11.3% additional oil over FW flooding. However, the results of organic and inorganic compatibility tests indicate that mixed water is less compatible with FW than industrial wastewater. The use of industrial wastewater without the process of separating suspended particles can lead to a 40% irreversible reduction in the absolute permeability of the core, and the separation process must be carried out in the optimal range, and the presence of sulfate-reducing bacteria (SRB) was confirmed in this wastewater. Nevertheless its population per unit volume of water is much less in wastewater than in Persian Gulf seawater. This alleviates the existing concerns in this area. According to different aspects, the results of this thesis indicate the high potential of industrial wastewater to be used in water-based EOR process
  9. Keywords:
  10. Enhanced Oil Recovery ; Low Salinity Water Flooding ; Industrial Wastewaters ; Wettability Alteration ; Core Flooding ; Total Suspended Solids (TSS) ; Sulfate Reduction Bacterias

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