Lanlei Guo

Surface Dilational Properties of Sodium 4-(1-methyl)-Alkyl Benzene Sulfonates: Effect of Alkyl Chain Length

Abstract The dilational properties of absorbed film of three sodium 4-(1-methyl)-alkyl benzene sulfonates at the air-water interface have been investigated by drop shape analysis method. The influences of time, dilational frequency and surfactant bulk concentration on surface dilational modulus and phase angle have been expounded. The nature of interfacial film depends on the molecular structure of surfactants. For 2Φ-14 and 2Φ-16, the diffusion-exchange process controls the dilational properties and the film shows viscoelastic character. As an increase of the hydrophobic chain, the dilational modulus of 2Φ-18 is independent on applied frequency in the studied bulk concentration except for 1 × 105 mol/L, which indicates the adsorbed layer behaves nearly purely elastic. Furthermore, the phase angle of 2Φ-14 and 2Φ-16 are remarkably higher than those of 2Φ-18, confirming that the presence of strong interactions between hydrophobic chains of 2Φ-18. Best agreements with the experimental data have been obtained from the curves of dilational modulus vs. surface pressure.

Fly Ash Particles Modified with Various Surface Coupling Densities and Its Thermal Stability Mechanism of Oil-in-Water Emulsion

The fly ash particle was modified with various surface coupling densities and IR testified that γ-glycidoxy propyl trimethoxy silane (GPMS) is located on the surface of it Vis chemical bond. The surface GPMS-coupling density could influence the hydrophilic–lipophilic properties of the particles. The contact angles increase with the increase of additive amounts of modifiers. It indicates the surface of fly ash changed from water wetting to oil gradually. Using DLS, the dispersion state of fly ash with different GPMS-coupling densities was studied. A suitable modification of fly ash with GPMS did not change the dispersion state significantly. To achieve good dispersibility in HPAM solution, the surface GPMS-coupling density should be controlled within the range of 1.4–3 μmol (m2 FA)−1. Using fly ash particle–surfactant–polymer system, the O/W emulsion stabilized is investigated to stable Pickering emulsion. The particle in surfactant and polymer solution synergistically interacted at the oil/water interface. The emulsion system of GPMS (2.98)-FA particles in PAM and SDS solution shows higher thermal stability as compared to other particles as it was dispersed very well on the emulsion interface.

Chemical Enhanced Oil Recovery Technology in Shengli Oilfield

The original oil in place suitable for chemical flooding in Shengli oilfield is 1.6 billion ton. Though the resource is abundant, the oil recovery is poor due to rigorous reservoir conditions, including high temperature, high salinity, high divalent-cation content, high oil viscosity and severe heterogeneity. In an effort to counteract the rigorous reservoir conditions, polymer flooding technologies for class I and II reservoirs has been improved, and surfactant/polymer flooding has been implemented industrially. Heterogeneous combination flooding technology has made great breakthroughs. A unique series of chemical flooding technologies has been developed and played a significant role in maintaining oil production in mature fields.

Rheological behaviors and secondary networks of polyacrylamide hydrogel filled with silica

Polyacrylamide (PAM) hydrogel filled with different types and contents of hydrophilic silica was synthesized by in situ polymerization. Rheological behaviors of the hydrogels were measured with an oscillation rheometer. The results indicated that the addition of silica efficiently improved the mechanical properties of the hydrogel, both for the uncrosslinked system and crosslinked system; simultaneously, the storage modulus (G′), loss tangent (tanδ) and viscosity (η) of the hydrogel were obtained. These results suggest that a nonbonded complexation existed between the silica and the molecular chains of PAM that endowed the hydrogel with special behaviors. Results from Fourier Transform infrared spectroscopy (FTIR) showed that the action of the nonbonded complexation was derived from hydrogen bonds between hydroxyl groups of silica and amide groups of PAM. The formed secondary networks endowed the hydrogels with high mechanical properties.