Synthesis and Characterization of TiO2 Nanoparticles for Enhanced Oil Recovery Applications
Ehtesabi, Hamide | 2015
- Type of Document: Ph.D. Dissertation
- Language: Farsi
- Document No: 47034 (48)
- University: Sharif University of Technology
- Department: Institute for Nanoscience and Nanotechnology
- Advisor(s): Taghikhani, Vahid; Ahadian, Mohammad Mahdi; Vosoughi, Manouchehr
- Enhanced oil recovery (EOR) techniques are gaining more attention worldwide as the proved oil is declining and the oil price is hiking. Although many giant oil reservoirs around the world were already screened for EOR processes, the main challenges such as low sweep efficiency, costly techniques, possible formation damages, transportation of huge amounts of EOR agents to the fields especially for offshore cases and the lack of analyzing tools in traditional experimental works, hinder the proposed EOR process.It has been shown that recently, nanoparticles are attractive agents to enhance the oil recovery at the laboratory scale.
In this study TiO2 nanoparticles were used to improve recovery of heavy oil from sandstone cores. Before performing core-floods, stability of nanoparticles at different salinities was tested using zeta potential and UV-Vis methods. While water recovered only 49% of the oil in the core flood experiments, 0.01% anatase structure solution recovered 80% of the oil after injecting two pore volumes at optimum conditions. To understand the mechanism responsible for improved recovery, contact angle measurements were performed on the rock surface before and after treatment with the nanoparticle solution. Contact angle measurements showed that the rock wettability changed from oil-wet to water-wet condition after treatment with nanoparticles. In 0.01% concentration, SEM results showed homogenous deposition of nanoparticles onto core plug surface and a few nanorods with diameter about 60 nm were observed. EDS confirms diffusion of nanoparticles in porous media and uniform distribution. By increasing the nanoparticle concentration, more nanorods with the same diameter were composed which resulted in plugging to occur.
Behavior of low concentration of TiO2 nanoparticles in core plug porous media and mechanism of increasing oil recovery were investigated. Flooding test with concentration of 0.01% TiO2 nanoparticles showed improvement in sweeping heavy oil from 41% to 55%. Inductively coupled plasma (ICP) results on exiting effluent of flooding test with concentration of 0.05% TiO2 nanoparticles showed the presence of only 0.5% of injected nanoparticles which indicate high affinity of the nanoparticles for deposition in porous media. Total amount of deposited TiO2 extracted from different cross sections of the core plug was consistent with the difference of injected and exited TiO2 material. At the entrance side, the amount of deposited TiO2 was high but decreased significantly in 0.1 cm depth, and reduces linearly versus distance. Based on surface area estimation of the core plug, only about one percent of the internal surface was deposited by nanoparticles. The viscosity, interfacial tension and contact angle measurements showed that the main mechanism for increasing oil sweeping is changing wettability of the rock surface from oil-wet to water-wet due to deposition of TiO2 nanoparticles. The role of the low concentration nanofluid in rapid displacing crude oil from the rock surface may be described by gradient pressure of nanoparticles in the three-phase contact wedge of oil, nanofluid and rock surface
- Nanomaterials ; Enhanced Oil Recovery ; Oil Tanks ; Water Injection ; Nanofluid