Search

Emulsion formation is one of the most important problems faced by petroleum companies to guarantee the flow of fluids during petroleum production, once its formation is often associated to the colloidal state of asphaltenes in petroleum. For this reason, chemical additives should be frequently used to stabilize the asphaltenes and reduce or prevent emulsion formation. Unfortunately, it does not exist any widespread chemical compound that could be used for petroleum reservoirs indistinctly. Consequently, scanning and screening analysis for new compounds should be performed with the purpose to find more efficient and eco-friendlier demulsifiers. In this paper, four different chemical routes (hydrogenation, ethoxylation, formaldehyde polycondensation, and ethoxylation of formaldehyde polycondensation) have been used to synthetize four new products from cardanol to evaluate their activity as demulsifier agents. These additives were characterized by FTIR and 1H NMR analysis. The demulsification activity were studied in emulsions using three Brazilian crude oil produced with a 30% (v/v) brine cut, 60 and 240 g/L NaCl of salinity, at different pH (range from 3 to 10), under agitation (3200 rpm). Bottle test was carried out at 60 °C in graduated tubes for water separability tests, by adding a constant composition (200 ppm) of each chemical tested. The results show that demulsification is more significant for ethoxylated compounds, at neutral pH.

Graphene oxide (GO) nanosheets have been experimentally proved to be a highly efficiency, rapid and universal demulsifier to break up the crude-in-water emulsion. The alkylamine functionalization of graphene oxide is well known as a way to turn graphene oxide highly affine with organic solvents. In the present work an amphiphilic material, graphene oxide functionalized by amino groups were prepared by Hummer’s modified method. We introduced it as a versatile demulsifier to break up crude-in-water emulsions. The amphiphilic material was characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD) and emission scanning electron microscope (SEM). The efficient demulsifier to break up crude-in-water emulsion was proved in synthetic emulsion using Colombian crude oil with different concentration. Demulsification tests indicated that graphene oxide amine-modified (GO-A) could separate the crude-in-water emulsion in a short time. Demulsification performance of amphiphilic material was made using the bottle test and evaluated by UV–Vis absorption spectroscopy to measure the final grease concentration after GO-A treatment.

Water-in-crude oil emulsions cause corrosion in upstream and catalyst deactivation in downstream oil processing. It is essential to demulsify and remove aqueous impurities from oil in production facilities. In this study carboxymethyl cellulose (Walocel), cellulose acetate, and two methyl cellulose with different methyl and 2-hydroxypropyl derivative contents (Methocel-K3 and Methocel-E5) are used as biocompatible polymeric water-in-crude oil demulsifiers. Screening bottle tests revealed that Walocel and Methocel-E5 are more suitable for deionized water-in-crude oil demulsification. Better performance of Methocel-E5 compared to that of Methocel-K3 is due to comparative abundance of methyl substitutes in Methocel-E5 which assist interaction with oil. Further demulsification experiments at different temperatures and demulsifier concentrations confirmed that Walocel is comparatively more effective than Methocel-E5 for deionized water- and saline-in-crude oil demulsification. An increase in temperature/demulsifier concentration favor demulsification via increasing the number of effective collisions between emulsified water droplets which destabilize the emulsion. Presence of ions slows down the demulsification of Methocel E5 more than that of Walocel. Better performance of Walocel is probably due to the abundance and strength of its directional hydrogen bonds as well as electrostatic and van der Waals interactions with water via its charged carboxy groups which are less affected by ion content of saline; thus, relatively retain their ability to weaken asphaltene- and resins-assisted water interaction with crude oil. The polar 2-hydroxypropyl substitutes in Methocel E5 provides comparatively reduced number/strength of hydrogen bonds as well as relatively weak van der Waals interactions with water molecules which are more severely affected by shielding impact of ions resulting in much less effective saline demulsification with Methocel E5.

Two kinds of hyperbranched poly(amido amine) (h-PAMAM) with abundant terminal amine groups are synthesized to break the oil-in-water (O/W) emulsions consisting of microdroplets. The demulsification performance of h-PAMAM is systematically evaluated with assistance of UV–vis spectra, micrograph, DLS and SAXS analyses. The demulsifier with 1,3-propanediamine as initiator shows a striking demulsification ability with small dosage (

The destabilization of oil-in-water (O/W) emulsions with average oil droplet sizes of less than 2 μm is important. Herein, hyperbranched poly(amido amine) (h-PAMAM) is successfully designed and synthesized by controlling the ratio of methyl acrylate (MA) to ethylenediamine (EDA) to enable the demulsifier to break microdroplets. The investigations on the effects of dosage, temperature, and settling time reveal that the demulsifier h-PAMAM with many NH 2 terminal functional groups displays a satisfactory demulsification performance. The oil removal ratio can reach 91% within 30 min at the demulsification equilibrium with the addition of h-PAMAM. This ability is primarily ascribed to the hyperbranched topology and abundant amino groups of h-PAMAM. Furthermore, measurements of the rupture rate constants of oil droplets and interfacial tension indicate that h-PAMAM is an excellent demulsifier. Dynamic light scattering (DLS) analysis can provide a new evidence for the exploration of the demulsification mechanism. The effective demulsification performance of h-PAMAM supports its potential applications in petroleum engineering.

During crude oil extraction, asphaltene-stabilized water-in-oil emulsions are formed and make the dewatering a challenging task. Demulsifiers (surface active agents), are typically used to destabilize the emulsion and facilitate the coalescence of water droplets. The demulsification mechanism of asphaltene-stabilized water-in-toluene emulsions by an ethylene oxide-propylene oxide-ethylene oxide (EO37─PO56─EO37) based block copolymer was studied. The performance of the demulsifier was assessed by bottle tests and the interfacial properties were determined by means of interfacial tension, Langmuir trough and contact angle measurements. From bottle tests experiments, the demulsifier showed the best performance at 3.85 µM in the water phase. A concentration dependent disruption of an asphaltene monolayer onto an aqueous polymeric surfactant subphase, was observed by means of Langmuir trough experiments. An interesting breakpoint was found at 0.154 µM aqueous polymeric surfactant concentration in the surface pressure-area isotherm, which is attributed to the formation of a new phase. Contact angle measurements of drops of aqueous polymeric surfactant solution onto asphaltene films showed that, at increasing polymeric surfactant concentration, the contact angle diminished to a threshold value. A direct interaction of block copolymer with asphaltene is proposed as a mechanism to account for the destabilization of water-in-oil emulsions.

Green oil-field chemicals based on ionic liquids (ILs) are highly recommended as demulsifiers for heavy crude oil emulsions due to their low vapor pressure, high thermal and chemical stability against degradation in harsh processing conditions. Novel multifunctional tricationic pyridinium ionic liquids (TCPyILs) were synthesized by the reaction of cyanuric chloride with tetraethylene glycol followed by its linking with quaternized aminopyridinium bromide using Bis(chloroethyl) ether as a linker. The chemical structures, surface and interfacial activities and thermal stabilities of the prepared pyridinium ILs were investigated. The amphiphilicity, surface and interfacial activity of the prepared TCPyILs recommended their application as chemical additives in petroleum industry. To the best of our knowledge, it is the first time to apply TCPyILs as demulsifiers for W/O emulsions with high stability and low droplet size (around 2 μm). Comparing with traditional monocationic pyridinium ILs, the prepared TCPyILs had higher efficiencies to demulsify W/O emulsions with different Vol %. The effects of alkyl chain lengths, demulsifier doses and RSN values on the demulsification activities were studied. The results indicated that TCPyILs with nonyl and tetradecyl alkyl chains had better and higher demulsification efficiency comparing with those containing hexadecyl alkyl chains. The demulsification efficiencies of TNPy and TTPy ILs for W/O (50/50, 30/70 and 10/90 vol%) reached 100% even at low concentrations.

Two star-shaped quaternary ammonium compounds, named as T-P-EDA and T-P-DETA, were synthesized with the melamine as the hydrophobic core and the quaternary ammonium moieties as the hydrophilic sub-core. Moreover, they were fully characterized by the FT-IR, 1H NMR, TGA and their demulsification properties were systemically investigated. It was found that both of the compounds showed higher demulsification efficiency than traditional linear cationic demulsifier (CW-01) in breaking the polymer flooding oil-in-water (O/W) emulsions. Notably, for a 1500 mg/L oil containing emulsion, it achieved ~99.5% oil removal ratio in 10 min at 30℃ by adding 80 mg/L T-P-EDA or T-P-DETA, while the oil removal rate of CW-01 was 93.5% at the same conditions. Furthermore, the interfacial tension, turbidity, and zeta potential measurements were performed, which indicated that the electrostatic interaction and hydrogen bonding between the demulsifiers and the surfactants were the driving forces for the enhancement of demulsification efficiency. T-P-EDA and T-P-DETA may potentially serve as the faster, more efficient and inexpensive demulsifiers.

Chemical demulsification is the most commonly used demulsification method for the separation of oil–water emulsions (W/O) in petroleum industry. Previous experiments demonstrate that the interfacially active asphaltenes (IAA) play the key role in stabilizing the heavy oil–water emulsions. Herein, the molecular dynamic simulation has been applied to reveal the molecular mechanisms on the stability and instability of the IAA-stabilized oil–water emulsions. It is found that IAA could accumulate at the oil–water interface and self-aggregate to form viscoelastic interfacial film through π-π stacking, hydrogen bonds (intermolecular and intramolecular) and other non-covalent bonds. Different types of hydrogen bonds (i.e., S = O…H-O, R-OH…H-O, N-H…N-R, S-H…S = O, S-H…S-R) are found between the IAA molecules due to the presence of heteroatoms (e.g., N, O, S) in IAA. Increasing the IAA concentration would increase the thickness of the IAA film which plays the key roles in stabilizing the emulsions. When the newly synthesized demulsifier (i.e., MJTJU-2) was added into the oil–water emulsion system, the oxygen groups (i.e., hydroxyl, ester groups, carboxyl groups, ether group) in demulsifier could weaken (at least 50%) or even break the hydrogen bonds and π-π stacking between IAAs and form new stronger hydrogen bonds with water molecules. This hydrogen bond reconstruction facilitates the breaking of the IAA film at the oil–water interface, allowing the coalescence of the water droplets in oil phase. This work would provide fundamental understanding for developing new way to efficiently demulsify the petroleum or similar oil–water emulsions.

Looking for efficient, environmentally-friendly, and low-cost demulsifiers for the separation of oil–water emulsion is the goal of oil industry. In current work, natural lotus leaf was used as raw material to prepare a HLLF demulsifier by a simple hydrothermal method without the addition of any chemical reagent. The HLLF demulsifier was utilized to demulsify the water-in-crude oil (W/O) emulsions. Effect of the demulsifier dosage, settling time, temperature and treatment method of HLLF on the demulsification efficiency (DE) was investigated. Encouragingly, the demulsification of the W/O emulsions could occur quickly, and the optimal DE was up to 88.17% with 1000 mg/L of dosage and 90 min of settling time at 70℃. Besides, it could effectively demulsify two types of crude oil emulsions from different oilfields. The possible demulsification mechanism was systematically investigated by scanning electron microscope (SEM), three-phase contact angle (CA), dynamic interfacial tensions (IFT), self-assembly of interfacial film and microscopic analysis. The CA value for HLLF was 81.53° and its IFT was 25.65 mN/m with the dosage of 500 mg/L at room temperature. The prominent demulsification ability of HLLF was attributed to the micro-nano structure on its surface, which may soften or destroy the rigid interfacial film to enhance the film drainage. The finding suggests that HLLF is a promising demulsifier for the separation of W/O emulsion, which exhibits a great application prospect in oil industry.

Graphene oxide (GO) nanosheets have been experimentally proved to be a highly efficiency, rapid and universal demulsifier to break up the crude oil-in-water emulsion and/or the emulsified oily waste water in our previous study. To recycle the GO nanosheets and avoid the possible contamination of GO for crude oil, in this work, the magnetic graphene oxide (M-GO) was successfully synthesized and used for separating oil/water emulsions. Demulsification tests indicated that M-GO could separate the oil/water emulsions within a few minutes and recycle 6–7 times without losing its demulsification capability. The residual oil content in the separated water was as low as ∼10 mg/L, corresponding to a demulsification efficiency of 99.98% at an optimal dosage. Quantum chemical calculation results indicated that the π-π/σ-π interactions between GO materials and asphaltene molecules are the major driven forces for the high demulsification performance of M-GO nanosheets. This work not only provides a promising demulsifies to demulsify the crude oil-in-water emulsion or the oily wastewater but also give a deep understanding on the intrinsic interaction between demulsifiers and asphaltenes.

In this research, the performance of three ionic liquids namely Trioctylmethylammonium chloride, Trioctylmethylammonium bromide and 1-Hexadecyltrimethylammonium bromide are evaluated as the demulsifier agents to break crude oil emulsion through the bottle test method. Then, the response surface method (RSM) is applied to investigate the effect of demulsifier concentration, temperature, pH and fresh water ratio on the dehydration efficiency of the prepared agents. The experiments are designed based on the central composite design method (CCD). To find the optimum conditions of input variables, an accurate model is developed to predict the dehydration efficiency of agents based on the statistical testing of various models by the analysis of variance (ANOVA). The results shows that temperature and pH of aqueous phase are two main parameters in the demulsification process and the maximum dehydration is attained at neutral value of pH and nearly the maximum temperature in the all samples. Then, the optimum operating conditions of agents are determined by RSM.

The increase in oil recovery from low salinity water injection has been often attributed to the alteration of wettability to water wetting. The increase in elasticity of the interface may also contribute to increase in oil recovery as has been suggested in the literature. In this work, we investigate oil recovery using two carbonate cores, one with large vugs, and the other without. The pore size and pore size distributions are very different in the two carbonate cores. The investigation centers on oil recovery from low and high salinity water injection, and by addition of an effective demulsifier molecule at 100 ppm in the injected high salinity water. The effective demulsifier molecule gives substantially higher oil recovery than low salinity and high salinity water injection. The oil-water interface elasticity increases significantly from the addition of 100 ppm demulsifier molecule to the aqueous phase. Salinity of the injected water is found to have a weak effect on oil recovery. We attribute high recovery performance of the 100 ppm surfactant to the increase in interface elasticity. The high recovery performance is observed in the carbonate reservoir rocks, both with and without vugs. The demulsifier molecule which is non-ionic has a very low adsorption in the carbonate rocks, around 2 mg/g at 100 ppm in high salinity injection water. This work introduces a new process for improved oil recovery by the introduction of a demulsifier molecule at ultra-low cocentration. The molecule has limited effect on water-wetting. The critical micelle concentration (CMC) of the non-ionic surfactant in the injected brine is at 30 ppm. The low adsorption, and the CMC indicate that the molecule adsorbs at the oil-water interface. The conventional chemical flooding which may require one or two orders of magnitude more material is through significant reduction of interfacial tension. The interface elasticity is singled out to be the main contribution to improved oil recovery in this work.

Oil industry has encountered a series of difficulties associated with flow assurance of petroleum fluids, especially those related with stable emulsion formation. Such emulsified systems could present problems during transportation, handling, and refining, because of their relation to operational factors, as follows: fluid viscosity, processing energy expenditure, and water coproduction. For this reason, the addition of interfacial active compounds, often polymers, is used in an attempt to phase separation in industrial processes. In this paper, five different chemical surfactants, referred to here as MACO 1, MACO 2, R1, R2, and R3, were synthesized based on castor oil. These additives were characterized by Fourier Transform Infrared (FTIR), Size-Exclusion Chromatography (SEC), and Thermogravimetrical Analyses (TGA). The demulsification activity was studied in synthetic emulsions by using two Brazilian crude oils and 30% (v/v) brine cut with 60 and 240 g/L NaCl, at neutral pH, and average droplet diameter of 10 μm. Bottle tests were carried out at 60 °C in graduated ASTM test tubes for 2 h, varying additive concentration from 100 to 5000 ppm. Interfacial tension measurements were performed to elucidate the demulsification activity in water-oil interface, at the same bottle test experimental conditions. These results were discussed on the basis of the oil characterization, mechanisms of demulsifying action, as well as interfacial tension data. Ward and Tordai equation was applied according to asymptotic approximations to evaluate additives diffusivity. The results show that demulsification is more significant for MACO 1, with maximum water resolution of around 90% for both emulsion systems.

This study reports a novel polyether-polyquaternium (PPA) demulsifier for demulsifying the O/W emulsion that originating from alkaline-surfactant-polymer (ASP) flooding produced wastewater. When processing an O/W emulsion that contained 500 mg/L oil, this PPA demulsifier exhibited a demulsification efficiency of 80.6% at 110 mg/L dosage, which is higher than that of a commercial polyamine demulsifier (65.9%) (designated S-01). This remarkable demulsification efficiency was ascribed to its abilities to reduce interfacial tension, thin interfacial films, reduce the elastic modulus and neutralize negative charges of the interfacial film. Oil droplets size distributions test results indicated that PPA could better aggregate the small oil droplets, which significantly favors the oil-water separation efficiency. By combining high-speed microphotography with the single-droplet method, the rupture kinetics data of the interfacial film were measured, which agreed with the demulsification principle of these two demulsifiers at various dosages. The microtopography difference of the original and demulsified interfacial film was also monitored using an atomic force microscope. Furthermore, the demulsification mechanism has been explored and confirmed according to all the characterization results. This novel integrated PPA reverse demulsifier with its high demulsification efficiency offers technical promise for oil removal from the ASP flooding produced wastewater.

Demulsifier is used in gas oil separation plants for the separation of water from crude oil emulsion. One of the important parameters for the enhancement of performance is the optimization of demulsifier formulation with respect to oil composition and produced water chemistry. The consistency in the quality of the formulation is essential to obtain the best separation of water throughout the production period of crude oil. The industry accepted method to optimize formulations is the bottle test method. However, this method remains laborious, time-consuming, imprecise, and requires access to fresh crude oil, which is not convenient from a practical viewpoint. Instead, routine physical and chemical properties are monitored to ensure the consistency of the demulsifier quality. It was, however, observed that there was a significant influence on the performance of a demulsifier from different batches with very close physical and chemical properties. Therefore, we developed a method using size exclusion chromatography to determine the molecular weight distribution of demulsifier base material, in this case, alkoxylated alkylphenol-formaldehyde resin. It was found that all the samples contained two well-separated species with one low molecular weight of about 2700 g/mol and other one with high molecular weight of about 15000 g/mol. The variation in the content of low and high molecular weight species was identified to be a key parameter significantly influencing the separation performance. It is apparent from this study that size exclusion chromatography could provide some additional insights on demulsifier intermediate chain length dispersity which could be correlated to actual separation performance.

The salts present in petroleum interfere in the characterization of its physicochemical properties, and from the measurements of these properties is established the price of crude oil. Therefore the water and salt need to be removed before these analyses. A new desalting apparatus was developed for heavy crude oils desalination by using demulsifier with water. The desalination process is accomplished in several washing steps and the extracted oil salts are monitored by ionic conductivity. Operational conditions were studied before and after the desalting process and the following parameters were evaluated: density, kinematic viscosity, total salinity index, total sulfur, total acid number and ionic conductivity. Using the proposed process it was possible to reduce the chloride content in the crude oil to values lower than 43 mg kg −1 of sodium chloride in petroleum with extraction efficiency about 99.87%. After the desalination process it was not observed significant changes in the intrinsic oil properties, and after the fourth wash of the oil there was a reduction of approximately 33% of total sulfur and total acid number content. These results indicate an improvement in oil quality, once the presence of sulfur compounds in the oil is undesirable because it increases the polarity of the oil, thereby increasing the polarity of the emulsions. These compounds are also responsible for the corrosivity of the petroleum products and produce harmful gases during combustion. Variations about 2% in API gravity and 3% in kinematic viscosity were not significant, indicating no change in the physical properties of the oils. The proposed procedure is faster (about 80 min) than the salt extraction method given by ASTM D6470 (about 140 min) for four washing cycles and it was possible to obtain a suitable condition for salt removal from heavy crude oil emulsions without toxic reagents.

This paper focuses on the synthesis of micro scale Poly(methylmethacrylate-acrylic acid-divinylbenzene) iron oxide Janus magnetic submicronic particles and the investigation of their interfacial properties and demulsifying capacity. The surface morphology, polymerization process and magnetic properties of the magnetic Janus submicronic particles were characterized by laser particle size analyzer, transmission electron microscopy, vibrating sample magnetometer. The interfacial activity and high hydrophilic nature of P(MMA-AA-DVB)/Fe 3 O 4 Janus magnetic submicronic particles allowed them to be effectively attached to stable emulsified water droplets in heavy crude oil water emulsion. Janus magnetic submicronic particles tagged water droplets were readily removed by an external magnetic field. Our experimental results showed efficient removal of the water from the heavy crude oil emulsion. It was found that external magnetic field enhances the coalescence of magnetically tagged water droplets in an emulsion. The magnetic property of P(MMA-AA-DVB)/Fe 3 O 4 allowed the used Janus magnetic submicronic particles to be readily recycled by magnetic separation and solvent washing. The recycled P(MMA-AA-DVB)/Fe 3 O 4 was found to retain its interfacial activity and was effective in breaking the heavy crude oil water emulsion. This study demonstrated that Janus magnetic submicronic particles demulsification represented a new route of removing emulsified water from crude oil and water emulsions.

Water-in-oil emulsions constitute a widespread issue for the oilfield industry. Indeed, the phases of water-in-oil emulsions must be separated as soon as possible in the production chain. These emulsions can be fairly stable due to certain intrinsic components in crude oil; therefore, adding chemicals – demulsifiers – to aid this separation is very common. Selecting the ideal demulsifier can save time and money, and in this context two-dimensional (2D) low-field nuclear magnetic resonance (NMR) is a promising technique because it allows for the separate study of the oil and water phases without the need for physical separation. In this study, four laboratory-made emulsions were used to investigate the demulsification process via low-field 1H NMR, allowing for the investigation of the correlation between the diffusion coefficient (D) and transverse relaxation time (T2) in 2D D–T2 plots. The three commercial demulsifiers used in this process (A, B and C) were characterised by positive-ion electrospray ionisation (ESI(+)) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The ESI(+)–FT-ICR mass spectra recorded for the commercial demulsifiers showed distinct chemical profiles, with two samples (A and B) being composed of surfactants containing isoprene and glycol propylene oligomer species, where the ions detected in the m/z 200–700 region were separated by m/z 42 and 58 units, respectively. A more abundant and complex chemical profile was observed for sample C, in which pyridine and sulphoxide analogue species were identified. The 2D D–T2 plots clearly showed that the separation of water and oil phases can be monitored and allowed for the classification of the demulsifiers according to their performance in the physical separation of the phases: demulsifier A > demulsifier B > demulsifier C.

Oil-in-water (O/W) emulsions are an innovate manner by which otherwise highly viscous heavy and extra-heavy crude oils can be transported from producing sites to transforming sites through pipelines. In spite of the important reduction in viscosity and pressure drops, water must be removed from the crude oil before further process or refining. Hence, the present study discusses the demulsification of an O/W emulsion prepared with Mexican heavy crude oil. A comparative study was carried out between microwave and oil bath heating with regard to water separation time. The effect of a chemical demulsifier and salt content of the O/W emulsion’s aqueous phase was also investigated. Microwave dielectric heating of O/W emulsions showed a greater degree of water separation in less time than conventional oil bath heating. Water separation of O/W emulsions increased with microwave power and salt content of the aqueous phase, and in the presence of a chemical demulsifier. Finally, the fluorescence emission spectra of the initial and treated O/W emulsions were in agreement with the water separation results and provide a quick and effective way to study the demulsification processes.

In the current study, the Aibel Vessel Internal Electrostatic Coalescer (VIEC) technology was tested for a real case scenario encountered in the production train of a UK oil field. Depressurized samples were collected both upstream and downstream of the first stage separator. The separation performance was discussed with respect to water cut and droplet size distribution of the emulsions, and the effect of chemical treatment. Issues with respect to representative sampling and testing have been discussed. The application of an external AC electrical field has been shown to significantly enhance the separation of the aqueous phase from tight emulsions, both when it was used alone and in combination with a commercial demulsifier. By using the VIEC technology, the time for separation could be reduced from 8 min to 2 min and the overall BS&W in the emulsions was improved from 45% or 60% to a residual water content of 5–20%. Destabilization of a 45% water-in-oil emulsion by electrical and chemical treatment (20/40 ppm) produced oil in the 2–7% BS&W range whereas the corresponding tests without applying an electrostatic field led to a BS&W greater than 25%. The achieved results strongly suggest that the VIEC technology can resolve the stable emulsion bands encountered in the Schiehallion train and add flexibility or increased production rate to the process. The results also suggest the importance of further studies on the destabilization performances achieved by electrostatic means.

Ways to improve the quality of highly weathered crude oils formed as a result of uncontrolled flow and seepage from damaged Kuwaiti oil wells were developed. Seven such oils collected from various lakes in different Kuwaiti oilfields had high contents of salts (up to 15 wt%) and water (up to 50 vol.%), high kinematic viscosity (815 mm 2 s −1 at 50°C) and low API gravity (8.2° API). Washing with fresh water removed the salt and water by up to 29 and 12 vol.%, respectively. Further washing increased the oil-water emulsion owing to the flocculant precipitation of waxy materials and high-molecular-weight compounds. The application of demulsifier, fresh water and heat broke the emulsion and allowed the water to settle out. The clean, water-free crude oil was similar in quality to a typical medium-API crude residue boiling > 300°C. This demonstrates that the oil had lost most of its light hydrocarbons.

Stubborn emulsions of distilled and artificial sea water in mixtures of Navy Special Fuel Oil (NSFO) and Navy Distillate (ND) have been broken by applying several approaches suggested by Lawrence some years ago. The effect of NSFO content, demulsifying agent structure and concentration, polymer concentration and salt concentration on the demulsifying process was studied. It was found that a commonly-used wetting agent, sodium di-2-ethylhexyl sulphosuccinate, was a particularly potent demulsifier and apparently superior to several commercial demulsifiers. The addition of a water-soluble polymer of high molecular weight intensified demulsifier action, while that of small quantities of an alkaline salt promoted separation in the most difficult cases, particularly those involving distilled water as the discontinuous phase.