Composition and Formation of Liquid Crystal Domains in Hydrocarbon Resources

Abstract

Interfacial properties play important roles in processes for hydrocarbon resource production, transport, and refining. Biplex liquid crystal domains, with diameters up to 200 μm, have been identified in unreacted heavy fractions of petroleum resources, particularly asphaltenes, worldwide. These liquid crystal domains comprise thin liquid crystal shells surrounding homogeneous cores dispersed in liquid. The identification of species comprising the shells has proven elusive because they are minor constituents of species present. In a recent work, we showed that produced water is enriched in liquid crystal domains relative to a hydrocarbon resource. In this work, gram quantities of liquid-crystal-rich materials were isolated from produced water. The isolation methods are described, and their compositions are analyzed using a combination of elemental analysis, Fourier transform infrared spectroscopy, and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The liquid-crystal-rich materials are shown to include humic substances (humic acid, fulvic acid, and humin) among the principal components. These surface-active and lyotropic liquid-crystal-forming materials are the only species known to be present that meet the constraints imposed by the analyses and self-assemble cooperatively. Validation experiments demonstrating the formation of lyotropic liquid crystal domains with solid and liquid hydrocarbon as well as aqueous cores + humic-acid-rich liquid crystalline shells dispersed in aqueous and hydrocarbon liquids were performed. The formation and behavior of liquid crystal domains in humic substance + hydrocarbon + water mixtures are analogous to those of oil−water−surfactant dispersions, where surfactants self-assemble on interfaces, forming a liquid crystal layer. Humic substances, common hydrocarbon reservoir constituents, may contribute to interfacial stability and surface deposition problems, arising in petroleum production, transport, and refining that are commonly attributed to asphaltenes because they appear to comprise a microscopic surphase on the exterior of asphaltene particles.

Influence of High-Molecular n-Alkane Associates on Rheological Behavior of the Crude Oil Residue

“…However, it is possible to find some studies, , where heavy crude oil rheological behavior differed from the Newtonian flow even in the temperature ranges of 70–90 °C. The supramolecular structures and microscopic and larger phase domains (including liquid crystal domains − ) impact bulk fluid densities, − transport properties (diffusivity and Newtonian and non-Newtonian rheological behaviors) . A similar behavior is true for the most natural bitumen samples. ,, Despite the fact that deviations from the Newtonian behavior of oil residues at 70–90 °C are small, they still indicate the heterogeneity of the studied oil dispersed system and the ongoing destruction of the oil dispersed system structures as a result of shear thinning.…”

“…A stabilizing effect on such emulsions can have such oil components as naphthenic acids, , asphaltenes, and its subfractions. Such like amphiphilic compounds can form liquid crystal layers and domains in crude oil. − Indeed, asphaltene and its subfractions are considered as well-appreciated stabilizers of water-in-oil emulsions due to their active surface that forms asphaltenic films at the oil–water interface. − The asphaltenic films depending on the concentration of dissolved asphaltene particles can be a monolayer or a layer of aggregated asphaltenes with 40–90 nm thick . Aggregated asphaltenes comprise a porous gel-like 3D network with viscoelastic properties.…”

Effect of Colloidal Stability and Miscibility of Polar/Aromatic Phases on Heavy Oil Demetallization

“…However, the excellent aqueous solubility would prevent the mass transfer of chemical reagents into the oil phase to make effective collisions with the organometallic compounds in the oil bulk, making it an interface reaction. Also, the liquid–liquid interface properties, such as apparent diffusion coefficients, solvent penetration, and phase separation rate, have great impacts on reactions. − Therefore, there is an irreconcilable contradiction between hydrophilicity and lipophilicity of chemical reagents during chemical demetallization.…”