There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Annual Energy Outlook

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Principles Of Enhanced Heat Transfer

Surfactants And Interfacial Phenomena

Despite the progress made on renewable energy, oil and gas remains the world’s primary energy source. Meanwhile, large amounts of oil deposits remain unrecovered after application of traditional oil recovery methods. Chemical enhanced oil recovery (EOR) has been adjudged as an efficient oil recovery technique to recover bypassed oil and residual oil trapped in the reservoir. This EOR method relies on the injection of chemicals to boost oil recovery. In this overview, an up-to-date synopsis of chemical EOR with detailed explanation of the chemicals used, and the mechanism governing their oil recovery application have been discussed. Challenges encountered in the application of the various conventional chemical EOR methods were highlighted, and solutions to overcome the challenges were proffered. Besides, the recent trend of incorporating nanotechnology and their synergistic effects on conventional chemicals stability and efficiency for EOR were also explored and analysed. Finally, laboratory results and field projects were outlined. The review of experimental studies shows that pore-scale mechanisms of conventional chemical EOR is enhanced by incorporating nanotechnology, hence, resulted in higher efficiency. Moreover, the use of ionic liquid chemicals and novel alkaline–cosolvent–polymer technology shows good potentials. This overview presents an extensive information about chemical EOR applications for sustainable energy production.

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An overview of chemical enhanced oil recovery: recent advances and prospects

Reducing surfactant adsorption on rock by silica nanoparticles for enhanced oil recovery

The surface and interfacial properties of five zwitterionic surfactants, including three propyl sulfobetaines CSB (where the carbon atom number of the alkyl chain is 12, 14 and 16, respectively) and two hydroxypropyl sulfobetaine surfactants CHSB (where the carbon atom number of the alkyl chain is 12 and 14, respectively), were studied at both air–water and oil–water interfaces. The surface activity of these surfactants at the air–water interface in aqueous solutions was investigated by the Wilhelmy plate method at 30 °C and ambient pressure. The values of the critical micelle concentration (CMC) and surface tension at CMC (γCMC) were determined from the surface tension measurements. The obtained results indicate that CMC and surface tension strongly depend on the surfactant molecular structure. An increase in the alkyl chain length results in a decrease in the CMC and γCMC values. The presence of a hydroxyl group causes an increase in CMC values and a decrease in γCMC values. The hydroxypropyl sulfobetaine surfactants have better surfacial properties. In addition, the interfacial activity at the oil–water interface among the crude oil–reservoir water–surfactant systems was investigated by use of the spinning drop method under harsh reservoir conditions of high temperature (90 °C) and high salinity (11.52 × 104 ppm, including 7040 ppm Ca2+ and 614 ppm Mg2+). It is interesting that the transient minimum dynamic interfacial tension (DITmin) could be observed in a specific concentration range. The time to reach DITmin is different with different surfactant molecular structures and surfactant concentrations. The hydroxypropyl sulfobetaine surfactant C14HSB shows excellent interfacial properties: it can reduce interfacial tension (IFT) between oil and water to an ultralow level at a very low concentration, and the ultralow IFT phenomenon only occurs in a specific concentration range from 0.03 to 0.10 wt%. In this work, hydroxypropyl sulfobetaine surfactants exhibit remarkable ability and are good candidates for chemical agents to enhance oil recovery in harsh reservoirs.

The structure effect on the surface and interfacial properties of zwitterionic sulfobetaine surfactants for enhanced oil recovery

Study on the synergy between silica nanoparticles and surfactants for enhanced oil recovery during spontaneous imbibition

Enhanced foam stability by adding comb polymer gel for in-depth profile control in high temperature reservoirs

A new kind of self-dispersing silica nanoparticle was prepared and used to enhance oil recovery in spontaneous imbibition tests of low-permeability cores. To avoid the aggregation of silica nanoparticles, a new kind of silica nanoparticle was prepared through the surface modification with vinyltriethoxysilane and 2-mercaptobenzimidazole as modified agents. Transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering, and ζ potential measurements were employed to characterize the modified silica nanoparticles. Dispersing experiments indicated that modified silica nanoparticles had superior dispersity and stability in alkaline water. To evaluate the performance of silica nanofluids for enhanced oil recovery compared to pH 10 alkaline water and 5 wt % NaCl solution, spontaneous imbibition tests in sandstone cores were conducted. The results indicated that silica nanofluids can evidently improve oil recovery. To investigate the mechanism of nanoparticles for enhanced oil...

Mingwei Zhao

Papers

Reducing surfactant adsorption on rock by silica nanoparticles for enhanced oil recovery

The structure effect on the surface and interfacial properties of zwitterionic sulfobetaine surfactants for enhanced oil recovery

Study on the synergy between silica nanoparticles and surfactants for enhanced oil recovery during spontaneous imbibition

Enhanced foam stability by adding comb polymer gel for in-depth profile control in high temperature reservoirs

Spontaneous Imbibition Investigation of Self-Dispersing Silica Nanofluids for Enhanced Oil Recovery in Low-Permeability Cores