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It is greatly desired to develop a high-efficiency demulsifier for the treatment of O/W emulsions in the production fluids of the petroleum industry. In this study, the amphiphilic Janus-SiO2 nanop...

Diatomite (DM) has superior adsorption performance for heavy metal ions in wastewater. However, the application of DM as a demulsifier in the treatment of a crude oil-in-water (O/W) emulsion has no...

The demulsification of oil-in-water emulsions with microdroplets has drawn great attention as a result of their extreme stability and difficulty of separation. In this work, a series of palmitoyl-hyperbranched polyethylenimine (CHPEI) with a hyperbranched structure was developed to meet the requirement of the demulsification. The influential factors of the demulsifier concentration, sedimentation time, and temperature on demulsification were investigated to give a clear view of CHPEI-based demulsification. The results indicated that the oil removal efficiency reached 91% by adding 80 mg/L CHPEI with sedimentation time of 30 min and showed a short sedimentation time and low addition amount compared to traditional demulsifiers. Further, to better acquire the mechanism of demulsification, the oil–water interfacial tension of CHPEI demulsifiers in aqueous phase and the real-time size changes of oil droplets were both recorded. These properties make CHPEI a potential candidate as an efficient demulsifier for c...

In the current study, novel environmentally friendly and interfacially active carbon nanotubes/SiO2 nanomaterials (CNTs/SiO2) for emulsified crude oil separation were prepared via grafting nano-SiO2 on the surface of oxidized carbon nanotubes (Ox-CNTs). The structure of the as-prepared CNTs/SiO2 was characterized by Fourier transform infrared spectroscopy, UV–visible absorption spectra, Raman spectra, X-ray diffraction spectra, thermogravimetric analysis, field-emission scanning electron microscope, and energy-dispersive X-ray spectroscopy. Besides, three-phase contact angles (θ) were employed to evaluate the wettability of CNTs/SiO2. Also, it was found that the θ value of CNTs/SiO2 was about 90°. The nanomaterials with interfacial activity can spontaneously assemble at the oil–water interface, thus improving the droplet coalescence in the emulsion. Afterward, the demulsification performance was evaluated in crude-oil emulsions using the bottle test, which demonstrated that the demulsification efficiency ...

The application of supercritical CO₂ (scCO₂)-flooding technology is increasing worldwide. After a waxy crude oil is treated with scCO₂, its composition and rheological properties are changed and the stability of its emulsion is accordingly altered as well, thus affecting the dewatering process in gathering stations. To probe the specific changes occurring in waxy crude oil and its emulsion after scCO₂ flooding, a scCO₂ treatment device was first designed to simulate the reservoir conditions. Next, the composition changes in the waxy crude oil caused by the scCO₂ treatment were studied, and the changes in the rheological properties, such as the pour point, viscosity, yield stress, and wax precipitation characteristics, caused by the composition variation were analyzed. Then, the stability of the degassed crude oil emulsion and the corresponding interfacial properties were examined. Finally, the demulsification characteristics of the emulsion under the action of a demulsifier were tested. The results reveal a content increase in the heavy components, such as asphaltenes, resins, and high-carbon-number hydrocarbons, in the waxy crude oil as a result of the scCO₂ extraction of the light components. This results in increases in the pour point, wax appearance temperature, and abnormal point as well as the growth of the apparent viscosity and yield stress. As a result of the structural enhancement of the interface, as reflected by the dilational modulus increase in the interface, the stability of the scCO₂-treated waxy crude oil emulsion is strengthened and its demulsification efficiency is reduced after dosing with the same demulsifier. All of these changes could unfavorably influence the safe transportation of the produced fluid in scCO₂-flooding oil fields and the subsequent dewatering process.

By adding an EO–PO demulsifier, the interface between the asphaltene model compounds and water was changed. The adsorption replacement of C5Pe or C5PeC11 molecules by an EO–PO demulsifier and the competitive adsorption between them were compared. A reduction of the interfacial tension of the C5Pe or C5PeC11–water interface by EO–PO demulsifier addition for the water-in-oil (W/O) and oil-in-water (O/W) systems was observed, suggesting higher interfacial activities of the EO–PO demulsifier, especially at high EO–PO demulsifier concentrations. Crumpling ratios of the flat C5Pe–water interfacial film for W/O and O/W systems were also measured, and the results showed that the EO–PO demulsifier was capable of softening and weakening the interfacial films for both systems. The EO–PO demulsifier showed similar performance on changing the C5Pe interfacial film through both diffusion (simulating the W/O system) and spreading (simulating the O/W system) protocols. By investigating the Langmuir interfacial-area isoth...

Asphaltenes tend to aggregate in different structures depending on the aromatic content of the oil phase. The different aggregates adsorb at the interface as some kind of lipophilic surfactant, whi...

The impact of mixing conditions on the removal of water and solids from high-water, poor-quality bitumen froth was explored. Naphtha diluent and a demulsifier were added to improve removal of water...

Acidic substances (naphthenic acids) were found in crude oil, which provides favorable conditions for the formation of surfactants. N,N-Dimethylcyclohexylamine (DMCHA) can activate the naphthenic acid in the crude oil to form the surfactant by noncovalent bonding. This process has an unusual meaning for the crude oil pipelines transportation by the method of forming a low-viscosity oil-in-water emulsion. At the same time, CO2 can be used as a demulsifier to separate crude oil and water at the end of pipeline transportation because the surfactant has a CO2 stimulus response characteristic. In our study, it was found that crude oil-in-water emulsion can be formed and has very good stability. CO2 has a high demulsification efficiency in emulsions with lower crude oil content. For high oil content conditions, the emulsion cannot be demulsified completely by CO2. Since sulfuric acid, hydrochloric acid, and the like are liquid and corrosive, this is not conducive to its application as a demulsifier in crude oil...

Amphiphilic poly(ionic liquids), PILs, derived from natural products attracted great attention as a green chemical in the field of the surface chemistry and petroleum industry. In the present work, new surface active PILs were synthesized from cardanol cashew nut oil as a hydrophobic alkyl phenol. The phenol group was etherified with diethanolamine, ethanolamine, and tetraethylene glycol using linking agent based on β,β-dicholorodiethyl ether to insert nonionic hydrophilic groups into cardanol. The amine group was quaternized with 2-acrylamido-2-methyl-1-propanesulfonic acid to produce polymerizable ionic liquids that polymerized to obtain new PILs. The chemical structure of the prepared new PILs was elucidated from 1HNMR and elemental analysis. The surface activity of the prepared PILs was determined from the surface and interfacial tension measurements of their aqueous solution. The ability of the prepared PILs to disperse the asphaltene fractions of the heavy Arabian crude oil was studied. It was used ...

Continuing depletion of energy resources and concerns over secondary pollution have driven interests in dewatering and recovering oil from oily sludge generated in the numerous petroleum processing operations, such as production, transportation, storage, and refining. The high viscosity and emulsified water droplets in the sludge have significant impact on the dewatering efficiency and deoiling efficiency, as well as recovered oil quality. In this study, a combination process of demulsification, viscosity reduction, and centrifugation was proposed for dewatering and recovering oil from high-viscosity oily sludge. Based on its rheological properties, two solvents for viscosity reduction and three demulsifiers were examined. According to the degree of viscosity reduction, the naphtha named 120# solvent oil was selected as suitable solvent. The polyether demulsifier P9935 was identified in terms of its dewatering efficiency. Following the addition of the naphtha and demulsifier P9935, both centrifugation spe...

Water-in-oil emulsions are formed during petroleum production. These emulsions are stabilized by natural emulsifiers present in the oil, such as asphaltenes, resins and paraffins, making their separation difficult. Various treatments can promote the breakdown of these emulsions, among them demulsification, which involves the addition of demulsifiers to promote separation of the water and oil phases. This work proposes the synthesis of demulsifiers by modification of branched polyethylenimine (PEI) with the introduction of different nonionic surfactants along the chain. Specifically, we used ethoxylated surfactants based on lauryl acid and nonylphenol, with different numbers of ethylene oxide units in their chains. The modified polymers were characterized by hydrogen nuclear magnetic resonance spectroscopy (1H NMR) and solubility tests. Demulsifier systems were prepared by dissolving the additives in two solvent mixtures: xylene:ethanol and xylene:butylglycol. These systems were applied in demulsification ...

Important differences arise when chemical demulsification strategies are implemented for heavy crude oils (°API ∼ 10). Traditional methods for screening and selecting an appropriate demulsifier based on bottle tests and lipophilic–hydrophilic parameters (i.e., HLB, RSN, and so on) tend to be less adequate because of the almost negligible density difference between the oil and the water phases. This situation leads to a detriment of the separated water often mixed with undesired dense-packed layers (DPLs) and emulsion layers. In this work, dehydration of heavy crude oil emulsions from a Colombian oilfield was assessed through the use of a wide range of chemical demulsifiers of different functionalities. Through the use of bottle tests and transmission/backscattering measurements, it was shown that the demulsification mechanisms involved in these limiting cases (low density difference) are different. Hence demulsifiers with functional groups that have traditionally performed very well for lighter oils fail ...

Using a silicone demulsifier is an efficient approach in the treatment of environmental pollution caused by aged oil. A new type of silicone demulsifier was prepared in this work by following a two-step synthesis method based on SP169 (octadecanol block polyether) and AE16 (monoamine fat alkyl block polyether). Reaction conditions, such as reaction time, temperature, and so on, were optimized for the synthesis of poly(ether ester) intermediates and silicone demulsifier. Both the 1H NMR and IR spectra confirmed the successful preparation of poly(ether ester) intermediates from acrylic acid based on the presence of the C=C and C=O bonds provided, indicating the successful modification of the silicone demulsifier by the polysiloxane and poly(ether ester) intermediates. The thermal degradation interval of the silicone demulsifier is 325°C–390°C according to thermogravimetric analysis. In addition, the diffusion and adsorption of the silicone demulsifier, which were measured by Quartz Crystal Microbalance with...

Two polyamidoamine-based dendritic molecules, named here as benzyl-G3 and octyl-G3, were synthesized using H2NCH2CH2NRCH2CH2NH2 (where R is either rigid benzyl or flexible octyl hydrophobic tails that are linked to the central nitrogen atom). With consideration of factors, such as the settling time, demulsifier dosage, temperature, oil content, and kinds of surfactants, the synthesized molecules were systematically investigated as demulsifiers for breaking up polymer flooding oil-in-water emulsions. In comparison to traditional G3 polyamidoamine, both benzyl-G3 and octyl-G3 exhibited better demulsification efficiencies with a dosage of 200 mg/L at a relatively low temperature (30 °C) in short periods of time (40 min) and reached 99.3 and 99.8% oil removal rates as they were added to the low oil-containing emulsion (1500 mg/L), respectively. A series of measurement methods were then adopted to explore the demulsification mechanism of the two demulsifiers. The interfacial tension and ζ potential measurement...

Demulsification with ethylene oxide (EO)-propylene oxide (PO) block copolymers is a very effective technique for treating water-in-oil emulsions in the petroleum industry. In this work, two series (A and B) of EO-PO block copolymers were synthesized and studied. The demulsifiers were defined by their relative solubility number (RSN) and interfacial tension (IFT). The performance of demulsifiers was evaluated by measuring the percent water and solids contents in dilbit product and hydrocarbon (diluent/ bitumen) losses to the underflow. Demulsifiers from series B showed higher performance on dilbit dehydration and demineralization as compared to demulsifiers from series A. The higher dehydration, and demineralization efficiencies for series B demulsifiers were a result of the higher adsorption and lower IFT values at the oil/water interface. Demulsifiers from series B also showed higher hydrocarbon losses to the underflow. These higher hydrocarbon losses were associated with higher solids-removal efficienci...

Chemical demulsification with EO-PO block copolymers is widely employed to treat bitumen froth in oil sands operations. In this effort, the relation between demulsifier properties and demulsification efficiency was explored using three EO-PO block copolymer demulsifiers, DMO A, DMO B, and DMO C. The EO-PO block copolymers were categorized by their relative solubility number (RSN) and dynamic interfacial tension (IFT). The dewatering and solids removal efficiencies of EO-PO block copolymer demulsifiers were in the order DMO C > DMO B > DMO A from 0 to 50 ppm dosage at 30 min settling time. DMO C also showed superior performance with lower hydrocarbon losses to the underflow as compared to demulsifiers DMO A and DMO B at all the dosages studied. The direct correlation was observed between the RSN values and dewatering/solids removal performance while the IFT does not correlate to the dewatering/solids removal efficacy of the EO-PO block copolymer demulsifiers. The influence of operating conditions such as p...

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Mixing conditions were explored as a possible avenue for improvement of demulsifier performance in the solvent-diluted bitumen dewatering process. The effects of demulsifier bulk concentration, demulsifier injection concentration, and mixing energy on water and solids removal from the oil phase were tested. All of the experiments were carried out in a confined impeller stirred tank, which provides well-characterized mixing conditions and relatively uniform flow and turbulence. Results showed that lowering the injection concentration and increasing the mixing energy both improve demulsifier performance, allowing a 50% drop in the bulk concentration of demulsifier. This result agrees well with an earlier study by Laplante et al.1 in which a different demulsifier was investigated. In that study, it was shown that the product of mixing time and energy dissipation rate at the feed point (the mixing energy = J) provides an alternate mixing variable.

The performance of several extended surfactants as water-in-crude oil emulsion breakers was evaluated using two criteria: (1) the demulsifier dose required (CD*) to attain the minimum stability at the so-called optimum formulation, and (2) the corresponding low minimum stability value. These surfactants were found to behave in the same way as typical commercial demulsifiers do; i.e., they require a lower dose CD* when their hydrophilicity is slightly greater. The reported data for a dozen different extended surfactants indicate how the two performance indices are altered by changing the structure characteristics, such as the propylene oxide number, the ethylene oxide number, and the ionic polar group (carboxylate, sulfate, phosphate). The best performance as a demulsifier seems to depend on the proper combination of these structures to attain a well-fitting compromise.

Hydrophilic surfactant molecules with the proper formulation are able to break W/O emulsions stabilized by asphaltenes and other lipophilic amphiphiles as found in the effluent of petroleum wells. The demulsifier performance is here tested according to two critera. The first one, as in previous research, is the minimum dose of demulsifier used to attain the minimum stability at the so-called optimum formulation in a simplified bottle test. The second criterion is the value of this minimum stability at optimum formulation that has a direct relation with the separation time. Our findings show that, in a family of ethoxylated surfactants, the best demulsifier is a hydrophilic one, though not too much. When the demulsifier is a mixture of two surfactants, it usually exhibits an intermediate behavior between the components. However, the mixture sometimes appears to be better than any of the components alone with some synergistic effect that improves the performance.

A new, magnetically responsive bacterial demulsifier (MRBD) was prepared by grafting magnetite (Fe3O4) nanoparticles onto the surface of demulsifying cells. The demulsification process and performance of the MRBD were investigated using a Turbiscan system. At a mass ratio of magnetite to demulsifying cells of 0.2, the demulsification ratio of MRBD increased from 70 to 80% in the presence of a magnetic field, the demulsification half-life decreased from 3.0 to 2.0 h, and the transmitted intensity increased 4 times compared with the native bacterial demulsifier. Analysis of the demulsification process revealed that an increased mass ratio improved the extent of drop coalescence by adjusting the balance between the surface hydrophobicity and magnetic responsiveness. The magnetic field mainly increased the drop sedimentation rate. The MRBD exhibited good recyclability and could be reused for three cycles, which may minimize demulsification costs. The simple synthesis and highly efficient demulsification perfo...

It has been known for years that the performance of a demulsifier in diluted bitumen dewatering improves up to a certain demulsifier bulk concentration. After this limit, the water removal deteriorates. This phenomenon is called overdosing. In this paper, the effects of mixing energy and demulsifier injection concentration on water removal are studied in systems with a high bulk demulsifier concentration. The experiments were conducted in a confined impeller stirred tank (CIST), which provides well-controlled mixing conditions with more uniform turbulence and flow than a conventional stirred tank. The results show that an increase in mixing energy and pre-dilution of the demulsifier may be able to overcome overdosing effects at a high bulk (mean) concentration. If the mixing conditions are well-designed, high local demulsifier concentrations at the feed point are avoided and the demulsifier can perform well, even at high bulk concentrations. The best demulsifier performance in an overdosed system was obta...

A major drawback associated with current hot or warm water-based bitumen extraction processes is the high consumption of energy. To address this issue, an aqueous–nonaqueous hybrid bitumen extraction process (HBEP), in which a portion of the diluent (solvent) was added upfront to soak mined oil sands prior to its water-based extraction, was proposed and demonstrated to be feasible to process mineable oil sands at ambient temperatures. This study investigates the effect of adding ethyl cellulose (EC) as a promising demulsifier to the solvent on bitumen recovery and froth quality in the ambient HBEP. The laboratory flotation results clearly showed a significant improvement in froth quality with a negligible setback on bitumen recovery by 100–200 ppm EC addition to the HBEP. Determined by an online visualization method, the addition of EC in solvent to the HBEP was found to further enhance separation kinetics of bitumen from sand grains of real oil sands ores. The addition of EC in solvent also increased the...

In the paper titled “Key performance indicators reveal the impact of demulsifier characteristics on oil sands froth treatment” by Ishpinder Kailey, [Kailey, I. Key performance indicators reveal the impact of demulsifier characteristics on oil sands froth treatment. Energy Fuels 2017, 31, 2636−2642] the author emphasized the importance of interfacial tension (IFT) and relative solubility number (RSN) on the performance of demulsifiers in the oil sand froth treatment. However, the IFT data analyses were incorrect, which led to wrong conclusions. The reason why demulsifier performance is related to RSN was not explained. In addition, the paper has issues with the experimental method and literature citation.

Seeking highly efficient, rapid, universal, and low-cost demulsification materials to break up the crude/heavy oil-in-water emulsion and emulsified oily wastewater at ambient conditions has been the goal of the petroleum industry. In this work, an amphiphilic material, graphene oxide (GO) nanosheets, Was introduced as a versatile demulsifier to break up the oil-in-water emulsion at room temperature. It was encouraging to find that the small oil droplets in the emulsion quickly coalesced to form the oil phase and separated with the water within a few minutes. The demulsification tests indicated that the residual oil in separated water samples was as low as similar to 30 mg/L, corresponding to a demulsification efficiency over 99.9% at an optimum GO dosage. More importantly, GO not only is useful for ordinary crude oil emulsion but also can be used to break up the extra heavy oil emulsion. The effect of the emulsion pH on the demulsification was also investigated. It was interesting to find that the. distribution of GO either in oil or in water phase after demulsification was dependent on the pH value of the solution, which was attributed to the pH-dependent amphiphilicity of GO. The prominent demulsification ability of GO was attributed to the strong adsorption between the GO nanosheets and molecules of asphaltenes/resins driven by pi-pi interactions and/or n-pi interactions. The findings in this work indicate that the GO nanosheets are a simple, highly efficient, and universal demulsifier to separate the oil from the crude/heavy oil-in-water emulsions at ambient conditions, which shows a good application prospect in the oil industry.

Demulsification of water-in-diluted bitumen froth emulsions is greatly affected by the presence of solids in the emulsions. In this paper, the wettability, composition, and particle size distribution of the solids extracted from bitumen froth emulsions and diluted bitumen after demulsification, in the absence and presence of a demulsifier, were investigated using partitioning tests, X-ray diffraction, and scanning electron microscopy. It was found that the application of the demulsifier assisted in the removal of water-wet solids, with the main components of the solids in the diluted bitumen being siderite and clays. The median particle size of the solids (D50) was reduced from 8 μm in the bitumen froth emulsions to less than 2 μm in the diluted bitumen phase after the use of a demulsifier in the diluted bitumen froth treatment. The presence of fine solids in the diluted bitumen froth increased the water/bitumen interfacial tension and increased the difficulty of demulsification because the fines are biwe...

It is well known that asphaltene molecules play a significant role in stabilizing emulsions of water in crude oil or diluted bitumen solutions: Molecular dynamics simulations were employed to investigate the aggregation anti orientation behaviors of asphaltene molecules in a vacuum and at various water surfaces. Two different continental model asphaltene molecules were employed in this work. It was found that the initially disordered asphaltenes quickly self-assembled into ordered hanoaggregates consisting of several molecules, in which the aromatic rings in asphaltenes were reoriented to form a face-to-face stacked structure. More importantly, statistical analysis indicates that most of the stacked polycyclic aromatic planes of asphaltene nanoaggregates tend to be perpendicular to the water surface. Tithe asphaltene molecules are considered as "stakes", then the asphaltene nanoaggregate can be regarded as a "fence". All the fence,like nanoaggregates were twined and knitted together, which pinned them perpendicularly on the water surface to form a steady protective ail wrapping the water droplets. The mechanism of stabilization Of the water/oil emulsions is thereby well understood. Demulsification processes using a chemical demulsifier were also studied. It was observed that the asphaltene protective film was destroyed by a demulsifier of ethyl cellulose molecules, leading to exposure of the water droplet. The results obtained in this work will be of significance in guiding the development of demulsification technology.

Waste water resulted from polymer flooding oil recovery generally has a bad impact on the subsequent process of enhanced oil recovery. Separating residual oil from oil/water (O/W) emulsion with suitable kinds of demulsifier is one strategy generally adopted by oil companies. Because of the existence of large amounts of ultrafine oil droplets with the average diameter less than 2 μm, the emulsions can be extremely difficult to break up. To solve this problem, an amine-based dendrimer demulsifier PAMAM (polyamidoamine) was synthesized in this study, and the efficiency of the demulsifier in dealing with O/W emulsions with ultrafine oil droplets was investigated. Because of its strong interfacial activity and relatively good solubility in water, the dendrimer-based demulsifier can easily attach to emulsified oil droplets in a stable diesel-in-water emulsion. The influences of temperature, settling time, and concentration of the demulsifier used on the efficiency of the demulsifier were investigated in detail....

Microwave radiation to promote the destabilization of water-in-crude oil petroleum emulsions is already an alternative technology for heating. Recent studies have suggested that microwave heating is more effective than conventional heating. This study assessed the following effects on the demulsification process: the aging of emulsions for the two types of heating (microwave and conventional), the time interval between microwave heating and the addition of a chemical demulsifier, and the time of microwave irradiation on the heating of petroleum and brine fluids. In addition, this study compared the efficiency of water separation by conventional heating and microwave heating regarding the (a) mean temperature of the emulsion and (b) temperature of water droplets. It was observed that water separation is less efficient for the two types of heating when the emulsion is subjected to aging. The efficiency of water separation using microwave heating is greater than with conventional heating when the mean temper...

The production of conventional crude oil and bitumen often faces the challenges in removing residual water from stable water-in-oil emulsions. The chemical demulsifier is commonly employed to enhance water removal because of its high efficiency and simplicity in operation. In this study, a novel magnetic demulsifier with a surface-active ethyl cellulose (EC) grafted on magnetic nanoparticle surfaces, called M-EC, was investigated for water removal from water-in-diluted bitumen emulsions. The M-EC was demonstrated to be interfacially active and magnetically responsive. The interfacial activity of EC on the surface of novel M-EC nanoparticles allowed them to be effectively attached to otherwise stable emulsified water droplets in diluted bitumen emulsions. The M-EC tagged water droplets were readily removed by an external magnetic field. When a simple magnetic separation was combined with tagging of emulsified water droplets by M-EC nanoparticles, our experimental results showed a more than 90% removal of t...

Water-in-oil emulsions of a crude oil were prepared and destabilized by addition of demulsifiers. The goal of the study was to compare two different techniques used to evaluate demulsification effectiveness and to study the interfacial response of the demulsifiers. The stability of these emulsions was determined in an ECrit cell and low-field NMR, and the interfacial response of the demulsifiers was measured with the oscillating pendant drop method. The ECrit cell measures the electric field required to induce the formation of free water and the NMR monitors the vertical movement of dispersed water droplets. The stability measurements and the interfacial response gave different indications on the demulsifier effectiveness at different demulsifier concentrations. The difference could be attributed to the difference between how the stability is measured or by the effect of the electric field on the demulsifiers. The separation profiles obtained in the NMR illustrated that the demulsifiers increase the sedim...

Processing of bitumen froth obtained from surface mining process of Athabasca oil sands yields stable water-in- diluted bitumen emulsions. Even with a demulsifier, a "rag layer" forms between the oil and free water layers when clay solids are present. Experiments reveal that wettability of clay solids has a significant effect on emulsion stability. Kaolinite in toluenebrine mixture was chosen as model system to study clay wettability alteration related to emulsion separation in bitumen froth treatment. Sodium naphthenate was added to simulate the presence of naphthenic acid in diluted bitumen. The fraction of the kaolinite that settled to the bottom of the aqueous phase was measured, and was referred to as"water-wet fraction",to characterize the wettability of kaolinite. Without any additives, 96% of the kaolinite was water-wet. Addition of only 100 ppm sodium naphthenate reduced the water-wet fraction to only 18%. Wettability of kaolinite was altered by pH control, silicate, and surfactant under different mechanisms. Addition of 366 ppm silicate at pH 10 resulted in 80% of kaolinite being water-wet. To prevent emulsion formation at high pH, cationic and amphoteric surfactants were evaluated as an alternative to alkali. Over 90% of kaolinite became water-wet when adding alkyl quaternary ammonium bromide, betaine, or amine oxide with optimal dosages.

Surfactant molecules are tested as water-in-crude emulsion breakers to attain the quickest separation rate in the so- called "proportional regime". A concept of demulsifier performance is proposed on the basis of the required demulsifier con- centration to offset the effect of a given amount of asphaltenes. The experimental evidence allows one to rank the tested products and relate their performance to their hydrophilicity and molecular weight. Some evidence indicates that the presence of acids in the crudemakesiteasiertobreakemulsionsandsuggeststhatso-called"extendedsurfactants"cansignificantlyshortenthedemulsifying process.

Initial processing of bitumen froth obtained using a water-based extraction process from Athabasca oil sands yields stable water-in-bitumen emulsions. When the bitumen is diluted with naphtha to reduce its viscosity and density, almost complete separation can be obtained with a demulsifier in the absence of clay solids. However, a “rag layer” persists between the oil and free water layers when clay solids are present. Effects of the naphtha/bitumen (N/B) ratio, demulsifier selection, and silicate dosage on the rag layer formation and product quality have been studied. Emulsions with a N/B ratio of 0.7 are more stable than those with a N/B ratio of 4.0. This can be partially attributed to the difference in viscosity and density affecting the sedimentation velocity. The residual water and solid contents in the oil layer decrease with the addition of silicate. This behavior is attributed to the effect of silicate on clay wettability. Clay solids have toluene-soluble organic contents, which vary as follows: i...

Selected cationic and amphoteric surfactants were effective in separating oil-in-water emulsions representative of produced emulsions expected during a surfactant/polymer (SP) process for enhanced oil recovery. The aqueous phase of the emulsion contained an anionic surfactant blend, alcohol, and partially hydrolyzed polyacrylamide. Brine composition was a suitable mixture of formation brine with brines from the surfactant slug and polymer drive. The crude oil had an American Petroleum Institute (API) gravity of 31°. Bottle tests were conducted at ambient temperature, which is near the reservoir temperature. Conventional non-ionic demulsifier resins and polymeric cationic flocculants were not effective in removing oil from the aqueous phase. The water content of the oil phase was still well above specification upon heating the emulsions to 50−60 °C. However, both oil and water phases of acceptable quality were obtained after 6 h of settling upon the addition of 200 ppm of octyltrimethylammonium bromide (C8...

Water/oil emulsions are formed in oil wells because of the presence of natural surfactants, such as asphaltenes and resins. These molecules strongly stabilize the water/oil interface and prevent coalescence of water droplets. Because water/oil phase separation is necessary before oil refining, surfactants are used to break water/oil emulsions. Herein, surface-active ionic liquids were synthesized and evaluated for the first time as demulsifier agents for water-in-crude oil emulsions of light, heavy, and ultra-heavy Mexican crude oil under conventional and microwave dielectric heating. The use of microwave irradiation accelerated and increased significantly the efficiency of demulsification of ultra-heavy crude oil emulsion.

International audience; In the presence of a large excess of asphaltenes in oil phase, an interfacial tension anomaly (a small bump of the order of 1 mN/m), is found to correspond to the optimum formulation where the fastest water-in-oil emulsion breaking is observed. This correspondence, also observed for other systems, indicates that strong interaction should occur between asphaltenes and demulsifiers. Therefore, the optimum formulation would correspond to a situation where there is enough demulsifier to remove the asphaltenic interfacial gel by orogenic displacement, but not too much to cause adsorption of large asphaltenic/demulsifier complexes which would slow down emulsion drainage.

The stability of water-in-diluted-crude-oil emulsions is found to depend upon the water-phase salinity and the water−oil ratio for different asphaltene and demulsifier concentrations. It is reported that the most stable emulsions are formed when one of the phase volumes largely exceeds the other and that the minimum stability is found at the formulation for which the emulsion inversion takes place. For asphaltene concentrations over 500 ppm, this occurs at a volumetric fraction between 0.3 and 0.7 and, in this range, the higher the water-phase content, the lower the required demulsifier concentration. It is also determined that there is an optimum value of the demulsifier concentration that promotes the fastest separation. At a fixed asphaltene concentration, an increase in salinity generally leads to a lower demulsifier requirement. Finally, at higher asphaltene concentrations, simultaneous increases in salinity and demulsifier concentration are required to attain an optimal rate of emulsion breaking.

Initial processing of Athabasca oil sands obtained from surface mining yields stable water-in-bitumen emulsions. When the bitumen is diluted with naphtha to reduce its viscosity and density, nearly complete separation can be obtained with a suitable coalescer in the absence of clay solids. However, a rag layer forms between the clean oil and free water layers when clay solids are present. We show here that complete separation in this case can be obtained by (a) adding a small amount of sodium silicate during initial emulsion formation to make the solids less oil-wet, (b) removing the clean oil formed following subsequent treatment with a demulsifier and adding sodium hydroxide or sodium silicate with shaking to destroy the rag layer and form a relatively concentrated oil-in-water emulsion nearly free of solids, and (c) adding hydrochloric acid to break the oil-in-water emulsion.

Surface-active chemicals (e.g., demulsifiers) are frequently used to destabilize crude oil emulsion. It was observed that, in some instances, when mineral solids were present, heavy oil emulsions were difficult to treat. Using three-phase contact angle measurements and videomicroscopy, the reasons behind the ineffectiveness of some demulsifiers were determined. It was found that adsorption of the surfactant onto solids changes the wettability of the solids, and promotes adhesion of the oil droplets to the solids thus reducing the effective density difference between the oil and the water, and hindering oil−water separation.

The fouling behavior of water streams in steam-assisted gravity drainage (SAGD) operations can be affected by chemical selection, including a reverse emulsion breaker, demulsifier, flocculant, and dispersant. Reverse emulsion breakers and demulsifiers were chosen to give the cleanest water quality and best dehydration during laboratory testing of reverse emulsions produced at SAGD facilities. A group of polyquaternary amine reverse emulsion breakers were synthesized to have a range of molecular weights with equivalent charge densities. The effect of their molecular weights on water clarification was investigated by standard bottle testing. It was found that the higher the molecular weight, the more effective the chemical was at removing suspected fouling agents. A flocculant has to be used with care to avoid overtreatment of the system. If fouling occurs during normal operation due to produced water from the primary separation vessel containing residual amounts of oil or other impurities, remediation can ...

In this work, we used polyoxyalkylenated diethylenetriamine (DETA) demulsifier with various polyethylene oxide (PEO) and polypropylene oxide (PPO) contents to destabilize a stable water-in-oil emulsion. The demulsifiers were characterized by the relative solubility number (RSN). The efficiency of emulsion destabilization was measured by the degree of separation of the oil and water phases. It was found that the destabilization of an emulsion is closely correlated with the PO and EO numbers. When the PO number in a molecule is much greater than the EO number, the surfactant gives a very low oil resolution rate, requires high dosages, and produces a stable middle phase. When a surfactant contains more EO than PO, it gives a high oil resolution rate at a low dosage, but it is easily overdosed, and some surfactants of this type (high molecular weight) also produce a stable middle emulsion phase. When the PO and EO numbers in the surfactant are close to equal, the surfactant breaks the emulsion rapidly at a ve...

Demulsification of water-in-bitumen emulsion was studied using 52 nonionic surfactants of different chemical families. Relative solubility number (RSN) and molecular weight were determined for these demulsifiers. Their dewatering performance was evaluated by determining the rate of water separation during gravitational settling and centrifugation. The results indicated that there is no overall correlation between demulsification performance and RSN value. However, within a given surfactant family, such as polymerized polyols, oxyalkylated alkylphenol formadehyde resins, and oxyalkylated alkyl resins, the degree of demulsification was found to correlate with the RSN value. A maximum of dewatering performance was observed in a specific RSN range for two surfactant families. Molecular weight also showed a significant effect on demulsification performance. Surfactants with low molecular weight (

The compatibility of asphaltic crude oil with demulsifiers in the electric desalting process was studied in this paper. The test result showed that asphaltene in crude oil causes the raising and abnormal of crude viscosity. Structure and character of asphaltic molecules make them easily gather and associate with each other at the oil/water interface and finally form a viscoelastic interfacial film of great mechanical strength. This not only interferes with the salt transfer from the oil to the aqueous phase, but also hinders the aggregation of the water drops, and thus affects desalting process of crudes. Several kinds of demulsifier series synthesized were used to investigate desalting and dewatering efficiencies in the electric desalting process. It was found that with the same initiator each emulsifier series had got an optimal proportion of propylene oxide (PO) and initiator. There also exists an ideal value of desalting and dewatering efficiency when demulsifiers were polymerized with ethylene oxide ...

The effect of paraffin in crude oil on the electric desalting and dewatering process was studied in this paper. The test result manifested that the dynamic viscosity of crude oil increased with the increase of paraffinic content in crude oil. Paraffin in crude oil exerts a great influence on the electric desalting and dewatering process because paraffin leads to higher viscosity of crude oil and emulsion stability as well as inefficient dewatering, and hence decreases the desalting efficiency. Some kinds of demulsifier series were tested in the process of the electric desalting and dewatering. The triblock copolymer structure of PO-EO-PO for polyhydric alcohol is more effective with high-paraffin crude oil than the diblock of PO-EO. Diamine series polymerized with propylene oxide (PO) were the most compatible with this type of crude oil for dewatering, whereas, polyamine series polymerized with propylene oxide (PO) and ethylene oxide (EO) were the most compatible for desalting.