Recent Advances in Nonaqueous Extraction of Bitumen from Mineable Oil Sands: A Review

Molecular dynamics investigation of the asphaltene-kaolinite interactions in water, toluene, and water-toluene mixtures

Understanding the interactions of petroleum asphaltenes with mineral surfaces is important for diluted bitumen spill response and modeling. In this study, molecular dynamics and umbrella sampling simulations are performed using interfacially active and non-interfacially active asphaltene model compounds individually positioned near each of the surfaces of kaolinite in the presence of explicit solvent environments containing water, toluene, and mixtures of toluene and water in varying proportions. The interfacially active asphaltene bonds the strongest to the silicon oxide surface of kaolinite in pure water and the bonding weakens to nearly zero in toluene-water mixtures. The non-interfacially active asphaltenes bond to kaolinites silicon oxide surface in water about half as strongly as the interfacially active one in water and the bonding weakens in the presence of toluene. The number of non-hydrogen bonded contacts between the interfacially active asphaltene and the aluminum hydroxide surface of kaolinite increases as the proportion of toluene is increased and the contacts with water are decreased. In these conditions, the non-interfacially active asphaltenes do not form non-hydrogen bonded contacts with kaolinite. On the silicon oxide surface, the number of non-hydrogen bonded contacts of all asphaltenes with kaolinite tends to decrease as the proportion of toluene is increased and the contacts with water are decreased. The number of hydrogen bonds of the interfacially active asphaltene with water decreases as the proportion of toluene is increased. The radii of gyration indicate that the interfacially active asphaltene is extended in water and when adsorbed on kaolinite, and becomes compact as the proportion of toluene is increased. The simulation results highlight the competitive interfacial interactions in the complex scenario of diluted bitumen spills in the presence of water and clay minerals.

A Review of Oil-Solid Separation and Oil-Water Separation in Unconventional Heavy Oil Production Process

Unconventional heavy oil ores (UHO) have been considered an important part of petroleum resources and an alternative source of chemicals and energy supply. Due to the participation of water and extractants, oil-solid separation (OSS) and oil-water separation (OWS) processes are inevitable in the industrial separation processes of UHO. Therefore, this critical review systematically reviews the basic theories of OSS and OWS, including solid wettability, contact angle, oil-solid interactions, structural characteristics of natural surfactants and interface characteristics of interfacially active asphaltene film. With the basic theories in mind, the corresponding OSS and OWS mechanisms are discussed. Finally, the present challenges and future research considerations are touched on to provide insights and theoretical fundamentals for OSS and OWS. Additionally, this critical review might even be useful for the provision of a framework of research prospects to guide future research directions in laboratories and industries that focus on the OSS and OWS processes in this important heavy oil production field.

Enhancing low-temperature thermal remediation of petroleum sludge by solvent deasphalting

Thermal treatment is a promising technique for treating petroleum sludge (PS). However, asphaltenes as a recalcitrant fraction of PS induce strong bounding between petroleum and minerals, and therefore lead to the need for high temperature and hence high energy consumption in thermal treatment of PS. In this study, a novel method combining a deasphalting pretreatment of PS with low-temperature thermal desorption (LTTD) was developed. The efficiency of deasphalting was found to be positively correlated to the ability of n-alkanes and asphaltene dispersants in dispersing asphaltenes. In treating six different kinds of PS, the residual oil contents were all below 2.5% after the deasphalting alone. Compared with direct thermal desorption at 600 °C for 1 h, dodecyl benzene sulfonic acid (DBSA)-assisted heptane deasphalting made thermal desorption at 350 °C for 1 h sufficient to treat these APS. The residual oil content of sludge after LTTD is lower than 0.45%. FT-IR, Raman spectra and XPS analysis confirmed that the carbon residue in APS after LTTD is primarily graphite state, which is extremely stable and does not migrate to the surrounding environment as compared with the crude oil in the APS. Hence, solvent deasphalting results in effective treatment of PS by LTTD, while the solvent can be recycled by distillation and crude oil recovered as value-added petroleum resource. The LTTD represents therefore a novel green strategy for treating PS and resource utilization.

Surfactants Enhanced Heavy Oil-Solid Separation from Carbonate Asphalt Rocks-Experiment and Molecular Dynamic Simulation

In this study, surfactants were used to enhance heavy oil-solid separation, and a detailed mechanism was explored by SARA (saturates, aromatics, resins, asphaltenes) analysis, element analysis, AFM measurement, and molecular dynamic simulation. Surfactants could effectively decrease oil/solid interaction force and then oil-solid separation would be enhanced. The oil-solid interactive force was in relation to surfactants concentration, pH value, asphaltene content, and salinity. The molecular dynamics simulation results show that the dissociation of saturated hydrocarbon, aromatic hydrocarbon, resin, and asphaltene (SARA) on carbonate minerals is gradually weakened for all surfactants. In the process of molecular dynamics simulation of surfactant stripping SARA, firstly, the surfactant molecules adsorb on the surface of SARA molecules. After that, the surfactant peels SARA molecules off the surface of calcite under the influence of molecular thermal motion. In this process, surfactant molecules will not be directly adsorbed on the surface of trace minerals. The results of energy/temperature balance indicated that saturates, aromatics and resins could remain stable when the molecular dynamics simulation time reached 2000 ps with the phenomenon that saturates, aromatics could liberate from minerals totally within 2000 ps. The molecular dynamics simulation of asphaltenes will not liberate from calcite surface within 6000 ps, meanwhile, they could not reach the energy balance/energy balance within 6000 ps. The functional groups of surfactant molecules would have interactions with the SARA functional group, resulting in different dissociation effects of SARA. The results of molecular dynamics simulation are consistent with the experiment results. The separation effect of saturated hydrocarbon, aromatic hydrocarbon, resin, and asphaltene in five kinds of surfactants were different. The molecular dynamic simulation results were in accordance with the SARA analysis.

Comparison of the Extraction Efficiency of Isoflavone Compounds from Puerariae lobatae by Ionic Liquids with 11 Anions and 8 Imidazolium-Based Cations

Although the field of natural product extraction with ionic liquids (ILs) is already a crowded one, the guiding rules regarding the selection of suitable ILs for extraction are still lacking. In this study, the extraction capacity of 32 ILs was investigated using Puerariae lobatae as a testing material, namely, 11 [BMIM]-based, 9 [CMIM]-based, 8 [C n MIM][Br] and 8 [C n MIM][BF4] ILs (n = 2, 4, 6, 8, 10, 12, 14, 16) were studied. Three series of concentrations (0.02, 0.50, 2.00 M) were investigated, and the results demonstrated that the extraction capacity increased with the rising IL concentrations except for 1-butyl-3-methyl-imidazolium tosylate ([BMIM][Tos]). Generally, all the 0.50 and 2.00 M ILs led to the best extraction results. At low concentrations, the IL extraction capacity is strongly dependent on the anions and cations. However, the relationship between extraction capacity and anions or cations gradually becomes weak as increasing IL concentrations. Finally, the solution of ILs was prepared in aqueous or 60% methanol depending on the solubility. The pH can vary from strong acid to weak alkaline. Extraction capacity of 32 ILs varying in concentrations has a good negative correlation with the pH, except for five [BMIM]-ILs.

Bitumen Recovery from Crude Bitumen Samples from Halfaya Oilfield by Single and Composite Solvents-Process, Parameters, and Mechanism

Since 2007, heterogeneous, high-viscosity active bituminous formations have often occurred during the drilling process in Yadavaran oilfield (Iran), Halfaya oilfield (Iraq), and tar sands (Canada). The formation of bitumen exhibits plastic and creep properties, and its adhesion is strong, so drilling accidents are easily caused, such as adhering vibrating screen, drill pipe sticking, lost circulation, and even well abandonment. These complex problems cause huge economic losses. Solvents used to dissolve bitumen are a feasible technology to remove bitumen effectively. In order to solve this problem, we used crude bitumen samples from Halfaya oilfield to study the relation between the bitumen component and different solvents. In this study, the temperature, crude bitumen sample to solvent ratio, stirring rate, stirring time, and ultrasound time on bitumen recovery by toluene were investigated by a single factor experiment. The optimum process parameter for bitumen recovery was obtained. Toluene, n-heptane, tetrahydrofuran, cyclohexane, cyclopentane, ethyl acetate, and n-pentane were chosen as the solvents for single solvent extraction and composite solvent extraction. The bitumen recovery increased significantly with the use of a composite solvent compared to a single solvent. The composite solvent ratio was 1:1. The highest bitumen recovery was 98.9 wt% by toluene/cyclohexane composite solvent. The SARA (saturates, aromatics, resins, and asphaltenes) components of the bitumen were analyzed. The toluene showed the highest asphaltene content, while the n-alkanes showed the lowest asphaltene content. The higher the asphaltene content, the higher the bitumen recovery. The composite solvent obtained the highest asphaltene content and bitumen recovery. The viscosity of bitumen extraction by different solvents was measured. The lower the bitumen viscosity, the higher the bitumen recovery. The element analysis indicated the solvent’s ability to extract bitumen colloids with the C/H ratio. This study provides a reliable theoretical basis for the subsequent adoption of effective anti-bitumen polluted drilling fluid additives.

Switchable-Hydrophilicity Triethylamine: Formation and Synergistic Effects of Asphaltenes in Stabilizing Emulsions Droplets

In this study, SHT (switchable-hydrophilicity triethylamine, [Et₃NH]·[HCO₃]) has been synthesized and instrumentally characterized by Fourier transform⁻infrared spectroscopy (FTIR) and ¹³C nuclear magnetic resonance (NMR). The operational synthesis conditions of SHT were optimized and determined at 25 °C, Et₃N/H₂O volume ratio of 1:2 and CO₂ injection rate at 300 mL/min. When it was used to extract heavy oil from unconventional oil ore, it was found that it could break maltenes-in-water emulsions. When asphaltenes were present in the oil phase, it was observed that SHT could cooperate with asphaltenes. These results indicated that SHT works with asphaltenes, leading to synergistic effects in stabilizing oil⁻water (o/w) emulsions.