Beh Hoe Guan

Synthesis and Characterization of Yttrium Iron Garnet (YIG) Nanoparticles Activated by Electromagnetic Wave in Enhanced Oil Recovery

Due to the geographical location and technological limitation, various novel enhanced oil recovery (EOR) methods has been proposed to recover the remaining oil from a depleted oil reservoir. Research on application of nanoparticles either on its own or coupled with other stimulating agents has been growing enormously and some of them have shown a promising future. In high temperature and high pressure reservoirs, thermal degradation will cause failure to the conventional chemicals. In this work, temperature-stable YIG magnetic nanoparticles with an electromagnetic wave has been proposed as a new candidate for reservoir stimulating agent. The purpose of nanoparticle injection is to increase the sweep efficiency in the reservoir by increasing the viscosity of displacing fluid. In this research, Yttrium iron garnet (YIG) nanoparticles have been injected into a waterflooded oil saturated porous medium to recover the remaining oil in the presence of an electromagnetic wave. At the sintering temperature 1200°C, a mixture of hematite and YIG was obtained, suggesting a higher temperature for single phase YIG. From VSM analysis, the average magnetic saturation, coercivity and remanence are 18.17 emu/g, 21.73 Oe and 2.38 emu/g, respectively. 1.0 wt% of YIG nanofluid was prepared and subsequently injected into the pre-saturated porous medium in the presence of square electromagnetic wave of 13.6 MHz. As much as 43.64% of the remaining oil in place (ROIP) was recovered following the injection of 2 pore volume of YIG nanofluid.

Synthesis and Characterization of Mesoporous Multi-Walled Carbon Nanotubes at Low Frequencies Electromagnetic Waves

For electromagnetic absorbing and shielding applications, carbon nanotubes (CNT) are widely used due to their excellent electrical and physical properties. Fabrication of microwave absorbing materials involves the use of compounds capable of generating dielectric and/or magnetic losses when impinged by an electromagnetic wave. The presence of lattice defects e.g. vacancies and dislocations contributes to the loss and attenuation in the electromagnetic waves, which in turn remarkably enhance the absorption ability of the material. With the CVD technique which is known to produce several lattice defects in the final product, aligned MWCNTs were successfully synthesized by pyrolizing toluene and ferrocene in an inert argon environment. The morphology analysis of the aligned MWCNTs was conducted via FESEM and TEM analysis, to reveal the average length of approximately 295 μm, with diameters in the range of 60-200 nm. EDS analysis indicates the high yield of CNTs, with more than 90% in weight composition, with less than 5 % Fe impurities presence. Textural properties of MWCNTs were studied by measuring pore size and BET surface area. To understand the response of CNTs to an electromagnetic field, permeability and permittivity measurement were conducted in the frequency range of 100 Hz to 110 MHz. In conclusion, the presence of defects in MWCNTs is desirable for enhanced electromagnetic absorption ability.

EMI Shielding Effectiveness of Composites Based on Barium Ferrite, PANI, and MWCNT

An electromagnetic interference (EMI) shielding material based on the composite of BaFe12O19, polyaniline (PANI) and multi-walled carbon nanotube (MWCNT) was proposed. The constituents of the composite were brought together through mechanical mixing and the in-situ polymerization of aniline on the BaFe12O19 and MWCNT surfaces. A series of composite with different MWCNT wt% loadings (0, 5, 10, 15, 20 and 25wt%) was prepared, and its effect on the EMI shielding performance was investigated. X-ray diffraction analysis was performed on all synthesized composites to confirm the phase formations. FESEM micrographs reveal the PANI particle formation on both BaFe12O19 and MWCNT surfaces. Electromagnetic measurements were done by using a rectangular waveguide connected to a network analyser to obtain the permeability, μr, permittivity, εr, and shielding effectiveness (SEA and SER). The increase in the MWCNT loading results in the enhancement of the composite’s shielding performance to a certain limit. Optimum EMI shielding performance is shown by sample PBM4 (20wt% MWCNT) with SER and SEA values of 5.14 dB at 8.2 GHz and 36.41 dB at 12.4 GHz, respectively. The influence of different MWCNT loadings (0, 5, 10, 15, 20 and 25wt%) on the EMI shielding performance of a composite consisting of BaFe12O19, polyaniline (PANI) and multi-walled carbon nanotube (MWCNT) were investigated.

Effect of Zinc Oxide Nanoparticle Sizes on Viscosity of Nanofluid for Application in Enhanced Oil Recovery

Zinc oxide (ZnO) with different nanoparticle (NP) sizes was prepared and synthesized by using the sol-gel method with organic precursor, followed by the characterization of the ZnO nanoparticle by using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) to identify the effect of nanoparticle sizes of ZnO on the viscosity of the nanofluid. The impact of nanoparticle sizes on EOR was investigated. Results showed both viscosity and interfacial tension (IFT) increased with the nanoparticle size.

Effect of Annealing Temperature on the Crystallization of Hematite-Alumina (Fe2O3-Al2O3) Nanocomposite and its Influence in EOR Application

Usage of magnetic materials is not unusual in oil and gas research, specifically in enhanced oil recovery (EOR) where various magnetic micro-and nanoparticles were used to enhance sweep efficiency, reducing interfacial tension and heat generation. Magnetic nanoparticles which are activated by a magnetic field are anticipated to have the ability to travel far into the oil reservoir and assist in the displacement of the trapped oil. In this work, magnetic Fe2O3-Al2O3 nanocomposite was synthesized and characterized for its morphological, structural and magnetic properties. At an annealing temperature of 900°C, this nanomaterial starts to exhibit magnetization as the composite structure crystallizes to the stable Fe2O3 and Al2O3. Subsequently, dispersion of the 0.01 wt% Fe2O3-Al2O3 nanocomposite in distilled water was used for displacement tests to validate its feasibility to be applied in EOR. In the displacement test, the effect of electromagnetic waves on the magnetization of Fe2O3-Al2O3 nanofluid was also investigated by irradiating a 13.6 MHz square wave to the porous medium while nanofluid injection is taking place. In conclusion, an almost 20% increment in the recovery of oil was obtained with the application of electromagnetic waves in 2.4 pore volumes (PV) injection of Fe2O3-Al2O3 nanofluid.

Impact of pH on zinc oxide particle size by using sol-gel process

Zinc oxide (ZnO) nanoparticles were prepared and synthesized via sol-gel method, by using citric acid as a precursor. The annealing temperature was fixed at 600 °C. The impact of pH on the particle size was investigated. Based on the results from the Thermogravimetric Analysis (TGA), three different pH for the precursor which is 3.0, 5.0 and 1.01 were chosen followed by the characterization of the ZnO nanoparticle by using Powder X-Ray Diffraction (PXRD), Transmission Electron Microscopy (TEM) and Field Emission Scanning Electron Microscopy (FESEM). Results showed that the crystallite size estimated from PXRD increased with the pH value which was hexagonal structure for ZnO. TEM further revealed the same tendency which the Zn NPs size also increased with the alkalinity of the precursor.

Numerical solutions for linear Fredholm integral equations of the second kind using 2-point half-sweep explicit group method

In this paper, performance of the 2-Point Half-Sweep Explicit Group (2-HSEG) iterative method with first order composite closed Newton-Cotes quadrature scheme for solving second kind linear Fredholm integral equations is investigated. The formulation and implementation of the method are described. Furthermore, numerical results of test problems are also presented to verify the performance of the method compared to 2-Point Full-Sweep Explicit Group (2-FSEG) method. From the numerical results obtained, it is noticeable that the 2-HSEG method is superior to 2-FSEG method, especially in terms of computational time.

An evaluation of iron oxide nanofluids in enhanced oil recovery application

This paper evaluates the oil recover efficiency of Iron Oxide (Fe2O3) nanofluids in EOR. Iron Oxide nanoparticles were synthesized at two different temperatures via sol-gel method. TEM results show that the Fe2O3 prepared at 300°C and 600°C were ranged from 10-25nm and 30-90nm, respectively. Results showed that the nanofluid composed of Iron Oxide nanoparticles prepared at 300°C gives 10% increase in the oil recovery in comparison with Fe2O3 nanoparticles calcined at 600°C.

Wettability, Interfacial Tension (IFT) and Viscosity Alteration of Nanofluids Under Electromagnetic (EM) Waves for Enhanced Oil Recovery (IFT) Applications

Zinc oxide (ZnO) nanoparticles (NPs) were prepared and synthesized via sol-gel method, by using citric acid as a precursor. The annealing temperatures were 500 and 800 °C which yielded average particle sizes of 56 and 117 nm, respectively. ZnO nanofluids of two different particle sizes (56 and 117 nm) were prepared using 0.1 wt% nanoparticles that were dispersed into brine (3 wt% NaCl) along with SDBS as dispersant. The impact of EM waves on wettability, viscosity and IFT of nanofluid was investigated. Results showed further reduction in wettability under EM influence with increased viscosity and reduced IFT. These results reveal a potential way to employ water-based ZnO nanofluids for enhanced oil recovery purposes at a relatively high reservoir temperature.

Effect of La3+ Substitution on the Structural and Magnetic Properties of Mn-Zn Ferrite Prepared by Sol-Gel Auto-Combustion Method

Spinel ferrite with the chemical formula of Mn0.5Zn0.5LaxFe2-xO4 (x = 0.02, 0.04, 0.06, 0.08, 0.10) were prepared by a sol-gel auto-combustion method. The effect of the rare-earth substitution on the microstructural properties of the synthesized powders were investigated through X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), while for the magnetic properties, vibrating sample magnetometer (VSM) measurements were made. XRD patterns revealed characteristic peaks corresponding to spinel Mn-Zn ferrite structures with accompanying secondary phases, such as Fe2O3 and LaFeO3. The initial addition of La3+ into the spinel ferrite system resulted in an initial spike of the lattice parameter and crystallite size before proceeding to decrease as the rare-earth content continues to decrease. FESEM micrographs reveals agglomerated particles with considerable grain size distribution. The magnetic properties, especially the saturation magnetization, Ms, was found to decrease with each increase in La3+ substitution. The research findings revealed the critical influence of the La3+ substitution towards the overall structural and magnetic properties of the Mn-Zn ferrite samples.