Design and Synthesis of Low Molecular Weight and Polymeric Surfactants for Enhanced Oil Recovery

Surfactants are defined as molecules able to lower the surface (or interfacial)tension at the gas/liquid, liquid/liquid, and liquid/solid interfaces. Due totheir properties, they are typically employed as detergents, emulsifiers, dispersants,wetting and foaming agents. In chemical enhanced oil recovery (cEOR), surfactantsare used as flooding agents, alone or in combination with polymers, alkali, and morerecently nanoparticles, to increase the microscopic displacement efficiency. Froma chemical point of view, surfactants are amphiphiles, meaning that they bear intheir structure both hydrophilic and hydrophobic moieties. Some naturally occurringsurfactants exists, but the majority are synthetic. The availability of syntheticsurfactants, allows a big variety of structures and properties. In this chapter, the mainclasses of surfactants will be reviewed, with focus on those used or proposed foruse for chemical enhanced oil recovery. After a general introduction about surfactantsand their main structural and physico-chemical properties, specific aspects ofdesign and synthesis will be discussed. Particular emphasis will be given to the mostrecent developments, which includes zwitterionic, gemini and polymeric surfactants.Own work of the author of this chapter in the field of polymeric surfactants will behighlighted

Where is research on fossil fuels going in times of climate change? A perspective on chemical enhanced oil recovery

In a society where the global search for renewable and sustainable sources of energy, chemicals and materials has rapidly become a priority, due to the challenges posed by climate change, one may think that there is no place anymore for research regarding extraction and production of fossil fuels. However, there is no denying that coal, oil and gas still constitute the major source of energy worldwide by far, and humanity will be dependent on them still for decades. As a matter of fact, the global demand of fossil fuels is still increasing rather than decreasing. However, fossil resources are consumed at a much higher rate than they are generated. Only focusing on crude oil, the chances of finding new conventional reservoirs are nowadays low, andthis conventional sources are quickly depleting, therefore it is necessary to turn more and more the attention to unconventional sources, such as carbonate reservoirs, tar sands, oil shales and deep off-shore reservoirs. Chemical enhanced oil recovery (cEOR) techniques are already well established in improving macroscopic and microscopic oil displacement, increasing oil production after primary and secondary methods are exhausted. However, these are mostly implemented in reservoirs that normally possess favorable conditions. Research can still contribute in making these processes more efficient and sustainable, especially for unconventional oil, for as long as we will need to extract fossil fuels. After supporting the idea that exploitation of fossil resources cannot stop just yet, this perspective article will highlight recent advances in the field of cEOR, mention-ing new developments in traditional methods, such as polymer and surfactant flooding, as well as newer methods, such as nanoparticles, preformed particle gels, and smart waterflooding, plus the various possible new combinations (hybrid EOR). This paper will finally try to shortly outline future directions of cEOR research, with emphasis on sustainable methods, such as CO2 flooding combined with carbon capture and storage strategies, and newly available research tools, such as reservoir-on-a-chip and machine learning

Anti-freezing conductive zwitterionic composite hydrogels for stable multifunctional sensors

Zwitterionic conductive hydrogels have shown potential application in wearable strain and pressure sensors. However, there are still fundamental challenges to achieve zwitterionic hydrogels with excellent mechanical properties, able to keep flexibility at sub-zero temperatures. To overcome these limitations, a zwitterionic conductive hydrogel was fabricated in this work by in-situ polymerization of aniline (ANI) monomer in a copolymer of sulfobetaine methacrylate (SBMA) and acrylic acid (AA) matrix. The obtained hydrogel possesses outstanding anti-freezing performance (without obvious loss of stretchability at −18 °C) and water-retaining properties, due to the introduction of LiCl on the zwitterionic polymer matrix. The synergy of chemical and physical crosslinking between poly (SBMA-co-AA) and polyaniline (PANI) networks enhance the mechanical performance of the zwitterionic hydrogel, that exhibits a fracture tensile strength of 470 kPa, and a fracture strain up to 600 %. Additionally, the integration of PANI confers stable conductivity (2.23 S m−1, maintained at 1.89 S m−1 even at −18 °C), high sensitivity (GF = 1.74), and short response and recovery times (223 ms and 191 ms, respectively). The hydrogel can be applied as a flexible sensor to accurately detect various human motions. This work provides a feasible strategy for developing wearable multifunctional sensors in a wide working temperature range.</p

Preliminary Evaluation of Amphiphilic Block Polyelectrolytes as Potential Flooding Agents for Low Salinity Chemical Enhanced Oil Recovery

Amphiphilic block polyelectrolytes are known for their remarkable thickening properties in water solution, originating from their ability to self-assemble into large micellar aggregates. This makes them promising flooding agent for chemical enhanced oil recovery (cEOR). However, to the best of our knowledge, they have not yet been directly investigated for this purpose. In this work, a survey of relevant properties for EOR (rheology, filterability and emulsification), and laboratory scale oil recovery experiments, were performed on water solutions of polystyrene-block-poly(methacrylic acid) amphiphilic block polyelectrolytes, and compared with a commercial partially hydrolyzed polyacrylamide (HPAM), to evaluate the real potential in EOR applications for the first time. It was found that the recovery of amphiphilic block copolymers in low salinity brine (0.2% concentration of NaCl) is remarkably higher than that of HPAM at comparable weight concentration and shear viscosity, despite a much lower molecular weight. Effect of salinity and emulsification properties of the studied polymers have also been preliminarily investigated. Our results suggest that the recovery mechanism of these polymers differs from the traditional mechanism of polymer flooding, possibly due to emulsification of the oil. In conclusion, the studied amphiphilic block polyelectrolytes show promise as chemical agents in low salinity polymer flooding

Metal vapour synthesis of stabilized transition metal nanoparticles: characterization, studies on factors affecting particle size and catalytic applications

This PhD thesis is focused on the synthesis, characterization and evaluation of catalytic activity of stabilized platinum and gold nanoparticles, generated by use of the metal vaporization technique. Metal vapour synthesis allows to obtain platinum and gold particles with diameters in the range of few nanometers. The introduction of suitable organic molecules at various stage of the synthesis has proven to be useful in order to control the final size of the produced particles. The metal nanoparticles obtained by this new approach are very stable and can be easily handled and characterized in solution. In particular, NMR based measurement of diffusion parameters has proven to be useful for the quick determination of particles size in solution. The choice of organic stabilizing ligand is crucial in determining both the particle size and the catalytic activity and selectivity of the system. Platinum particles characterized by small diameters and good catalytic performances are obtained using vinylsiloxanes and aromatic solvents while, in the synthesis of gold particles, branched thiols and alkylamines demonstrated to be a better choices over linear alkylthiols if catalytic activity is required. A new application of gold nanoparticles in catalytic silane alcoholysis reaction has also been discovered

Acetalised Galactarate Polyesters:Interplay between Chemical Structure and Polymerisation Kinetics

In spite of the progress that has made so far in the recent years regarding the synthesis of bio-based polymers and in particular polyesters, only few references address the optimisation of these new reactions with respect to conversion and reaction time. Related to this aspect, we here describe the transesterification reaction of two different acetalised galactarate esters with a model aliphatic diol, 1,6-hexanediol. The kinetics of these two apparently similar reactions is compared, with a focus on the conversion while varying the concentration of a di-butyltin oxide catalyst (DBTO), respectively, the used N2 flow-rate. During the first stage of polymerisation, the molecular weight of the end-products is more than doubled when using a 250 mL/min flow as opposed to an almost static N2 pressure. Additionally, the resulted pre-polymers are subjected to further polycondensation and the comparison between the obtained polyesters is extended to their thermal, mechanical and dielectrical characterisation. The influence of the acetal groups on the stability of the polyesters in acidic conditions concludes the study

The effect of macromolecular structure on the rheology and surface properties of amphiphilic random polystyrene-r-poly(meth)acrylate copolymers prepared by RDRP

In this work rheological and surface properties of various random copolymers of styrene and sodium (meth)acrylate, prepared using reversible deactivation radical polymerization (RDRP), were studied. It is shown that the properties of these polymers in water solution, relevant for several applications, are affected by their chemical structure and molecular weight. Cryo-TEM images of their concentrated water solutions do not show the presence of nano-objects as micelles, however the existence of some aggregates seems to be confirmed by fluorescence measurements using pyrene as a hydrophobic probe and by surface tension measurements. Moreover, interesting results are displayed about the viscosity as well as the surface tension of these water polymer solutions, due probably to different interactions at the molecular level as suggested by fluorescence measurements.</p

Polymeric surfactants for enhanced oil recovery:A review

AbstractChemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are well established, but new challenges always emerge, which give impulse to the search for new solutions. Polymeric surfactants represent a very attractive alternative to these techniques, because they can provide simultaneously increase in water viscosity and decrease in interfacial tension, both beneficial for the efficiency of the process. The analysis of the literature shows that the use of polymeric surfactants as displacing fluid has the potential to improve the performances of EOR in some cases. However, the synthesis are often challenging and costly and the available data about the real performances of such systems in oil recovery are still sparse. This holds back the possibility of a significant use of polymeric surfactants for EOR. This review collects the relevant work done in the last decades in developing and testing polymeric surfactants for EOR, with a particular emphasis on the chemical aspects, the patent literature and bio-based systems

Design of a pH-Responsive Conductive Nanocomposite Based on MWCNTs Stabilized in Water by Amphiphilic Block Copolymers

Homogeneous water dispersions of multi-walled carbon nanotubes (MWCNTs) were prepared by ultrasonication in the presence of an amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) copolymer. The ability of PS-b-PAA to disperse and stabilize MWCTNs was investigated by UV-vis, SEM and zeta potential. The results show that the addition of a styrene block to PAA enhances the dispersion efficiency of the graphitic filler compared to pure PAA, possibly due to the nanotube affinity with the polystyrene moiety. Notably, the dispersions show an evident pH-responsive behavior, being MWCNTs reaggregation promoted in basic environment. It is worth noting that the responsive character is maintained in solid composites obtained by drop casting, thus indicating potential applications in sensing