Demulsification Of Crude Oil Emulsions Research Articles

Demulsification of water-in-oil emulsions using ionic liquids: Effects of counterion and water type

Demulsification of crude oil emulsions is of significant interest in the petroleum industry. This study aims to investigate the effect of ionic liquid (IL) counterions and water type (distilled water (DW) and laboratory formulated seawater (SW)) on the demulsification of water-in-oil (W/O) emulsions. Three ILs belonging to the phosphonium compounds with different counterions were used. These ILs were designated as THPC (contains chloride ion), THPD (contains decanoate ion), and THPDc (contains dicyanamide ion). Emulsions were formed using DW and SW while demulsification tests were conducted at temperatures of 60 °C and 80 °C. According to the demulsification outcomes at 60 °C, THPC was the best candidate for breaking W/O emulsions produced from DW while THPD and THPDc were excellent candidates for destabilizing emulsions produced from SW. The optimal percentage demulsification efficiency (DE) achieved for emulsions from DW was 99% with just 1000 ppm THPC while 1000 ppm THPD and 700 ppm THPDc are adequate to bring about excellent water separation in emulsions formulated from SW. THPD and THPDc also attained the maximum percentage DE of 99%.On the other hand, at elevated temperature (80 °C), THPC, THPD, and THPDc attained nearly the same water separation in the W/O emulsions produced from DW and SW with a demulsifying capacity of 99%. However, demulsification activities at this temperature (80 °C) in the W/O emulsions formed using SW were very fast as compared to what was observed in the case of emulsions obtained from DW. Thus, salts present in SW have propensities to accelerate the destabilization of crude oil emulsions. Viscosity and elastic modulus time sweep measurements reveal that the tested ILs can collapse the natural emulsifiers (asphaltenes and resins) existing at the water-oil interfaces.

Demulsification of Crude Oil Emulsions Tracked by Pulsed Field Gradient (PFG) Nuclear Magnetic Resonance (NMR). Part I: Chemical Demulsification

Emulsified water droplets must be extracted from crude oil for economical and transport purposes, which is achievable by chemical demulsification. Four different chemicals were tested on water-in-crude oil emulsions using a newly developed nuclear magnetic resonance (NMR) method. Droplet size distributions were mapped at the beginning and end of experimentation. In addition, slice selections (soft radio-frequency (RF) pulses) were used to isolate the signal from residual droplets within the separated oil phase to study coalescence patterns in the emulsion bulk. The NMR could also return rapid continuous brine profiles for analysis of sedimentation rates and free water appearance kinetics. The residual water content was isolated by strong bipolar gradient suppression, thereby allowing focus on the smaller droplets still emulsified in the top region in the brine profiles. Optimum concentrations were found for each chemical, and blends of several chemical demulsifiers were noticeably more efficient than the ...

Demulsification of crude oil emulsion via electrocoagulation method

During oil production and processing emulsions were formed and seriously cause problem, both in terms of chemicals used and production losses. The traditional methods of breaking crude oil emulsions are disadvantageous from both economic and environmental perspectives. In this paper, the potentials of electrocoagulation technology in demulsification of crude oil emulsion were investigated. The crude oil obtained from Petronas Ponapean Melaka, Malaysia. For stability performance test, Span 80 was used as emulsifier, while for chemical demulsification performance test,Hexylamine was used. The electrocoagulation method was used for demulsification of W/O emulsion. For electrocoagulation demulsification, three factors namely; voltages 15-50 V, current density 1.04-3.94 mAcm-2, and concentration of NaCl 0.5-2.5 g/L. The electrocoagulation demulsification showed that the best water separation efficiency was achieved at voltage 50 V, current density 3.94 mAcm-2, and NaCl concentration 2.5 g/L, whereas the separation efficiency reached at 98%. Results have shown the potential of electrocoagulation method in separation of water-in-crude oil emulsions, W/O.

​Demulsification performance, behavior and mechanism of different demulsifiers on the light crude oil emulsions

Chemical demulsifiers were widely applied for demulsification of crude oil emulsions which were generally formed with natural stabilizers during the extraction. Based on our previous study of the light crude oil emulsions stability, the demulsification performance of four classes of nonionic poly(ethylene oxide) poly(propylene oxide) copolymer demulsifiers and sodium dodecyl sulfate (SDS) as well as their dynamic demulsification process on the W/O light crude oil emulsion were analyzed by the multiple light scattering method. The demulsification mechanism of these demulsifiers were illuminated by the measurement of dynamic interfacial tension (IFT), dynamic interfacial viscoelasticity, rupture rate and microscopic changes of oil film by single droplet method. The results have shown that demulsification performance doesn’t depend on IFT, though effective demulsifiers could have a lower IFT around 1 mN/m. Multiple light scattering data and dynamic IFT clarified the demulsification process of efficient demulsifiers, quick diffusion and adsorption of demulsifiers, palpable change in interfacial property, droplet coalescence and sedimentation. The capacities of demulsifiers to penetrate into the interface and to decrease the interfacial viscoelasticity were the dominating demulsification mechanisms. The quantitative interpretation of multiple light scattering data associated with the dynamic IFT and interfacial viscoelasticity illuminated the demulsification mechanism of different demulsifiers. The rupture rate and dynamic rupture process of the oil film between the aqueous phases also vividly showed the differences in demulsification process. The nonionic demulsifiers AR902 and PR929 with aromatic groups has the highest speed and best performance due to the similar aromatic groups with those in asphaltenes, which produced the least stable oil film. This study provides a valuable guideline for the selection of demulsifier for light crude oil emulsions and enhanced demulsification mechanism studies.

Synergistic Effects of Alum and Demulsifier on Demulsification of Crude oil Emulsions

Water in oil emulsions create problems in all oil field. These emulsions are generally destabilized by thermal, chemical and electrical methods or by employing some ionic or non-ionic surfactants in combination with thermal or electrical methods. It is known that clays affect the stability of these emulsions. Some researchers have reported the effect of ionic liquids in improving the demulsification of emulsions partly stabilized by clays. Therefore, an attempt was made to examine the synergistic effect of alum and demulsifier and it was found that at high concentration of demulsifier plus alum, the demulsification rate is abnormally increased. For effective demulsification, demulsifier dose of 10000 mg/l was found to be the best dose.

Effect of polar head surfactants on the demulsification of crude oil

ABSTRACTSurfactants can act as demulsifiers to neutralize the stabilizing effect of natural emulsifiers in crude oil. Here, the effect of polar head group of surfactants with identical hydrophobic chain C12 (SLES, SLS, C12E23, BKC, C12E7) on the demulsification of crude oil emulsion and its effect on water separation rate were studied at different temperature. The activation energy for destabilization was calculated. The results indicate that the rate of water separation increases with temperature and surfactant concentration. The emulsion destabilising activation energy decreases as the concentration of the surfactant increases. The Interfacial Tension (IFT) study showed that when the reduction in IFT was the highest, the water separation rate and efficiency achieved was the highest.

Application of the response surface methodology for modeling demulsification of crude oil emulsion using a demulsifier

ABSTRACTThe main objective of this research is to determine the capability of four surface-active compounds namely poly(ethylene glycol) distearate, N,N-dimethyldodecylamine N–oxide solution, polyoxyethylene (10) tridecyl ether, and polyethylene glycol sorbitan monooleate as demulsifier agents in breaking water-in-crude oil emulsion through the bottle test method. The influence of temperature, concentration, water content, and pH on demulsification efficiency of the studied demulsifiers was investigated via the response surface methodology (RSM) and the central composite design method (CCD) was applied to design the experiments. The optimum values of input variables to obtain the maximum water separation efficiency were determined based on the developed model by analyze of variance (ANOVA). The R-squared values demonstrate that the developed models could appropriately predict the experimental results of all demulsifier agents.

MPEG grafted quaternized carboxymethyl chitosan for demulsification of crude oil emulsions

ABSTRACTFour novel environmentally friendly and highly branched crude oil demulsifiers were prepared by using different molecular weight (Mn = 350, 750, 1000, 1900 g/mol) of methoxy poly(ethylene glycol) to modify quaternized N,O‐carboxymethyl chitosan. Fourier transform infrared and 1H‐nuclear magnetic resonance were employed to confirm the structure of the demulsifiers. The surface tension of demulsifies was determined and hydrophile–lipophile balance value was calculated at the critical micelle concentration. The demulsification performance was evaluated by the bottle test method against water‐in‐oil emulsions simulated in the laboratory and it was found that the dehydration rate of four demulsifiers can come to 74.2%–80.4%, which have better demulsification performance than the commercial demulsifier JL‐1. Demulsification mechanism was discussed, and it was encouraging to find that the tiny water droplets in the emulsion coalesced to form the water phase and separated with the water from the polarization microscope. Results show that methoxy poly(ethylene glycol) grafted quaternized carboxymethyl chitosan has a promising application as a demulsifiers for dealing with W/O crude oil emulsions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45867.

An Experimental Study on the Application of Ultrasonic Technology for Demulsifying Crude Oil and Water Emulsions

An emulsion is the mixture of two immiscible fluids, where one fluid appears as droplets within another. In the oil and gas industry, produced crude oil generally comes with an appreciable amount of water within it in an emulsified form. Before produced crude oil can be prepared for purchase, the water associated with it must be removed. A process known as demulsification is required in order to separate an emulsion into its two phases. In the industry, a number of demulsification techniques are already present; these include thermal, mechanical, chemical, and electrical techniques. Crude oil and gas produced from wells originally come with water, salts, and volatile gases such as oxygen, carbon dioxide, and sometimes hydrogen sulfide, etc. Hence, the petroleum mixture needs to be refined-water, salt, and non-hydrocarbon gases to be separated from the mixture, in order to meet certain oil and gas specifications (which state the maximum concentrations of such contaminants) and make it ready for purchase and transportation. Sonication provides a cheap, simple, and harmless (as it involves mainly the propagation of sound waves) way of separating crude oils from water droplets via demulsification. In addition, if needed, it can be used for emulsification processes as well. Hence, a study of sonification as a way for crude refinement or chemical mixing has important implications for the oil and gas. This investigation proposes the use of ultrasonication as a new and cost-effective technique to aid in the demulsification of crude oil emulsion. The effectiveness of this technique was gauged through its comparison to the already present methods in the industry. Based on the investigation it was found that centrifuge served as the best demulsification method for it reduced the turbidity by 86%. In addition, the reduced turbidity achieved with proposed ultrasonication method ranges from 20%-60%.

Effect of ultrasonic frequency on separation of water from heavy crude oil emulsion using ultrasonic baths

In this work, a comprehensive study was performed for the evaluation of ultrasound (US) frequency for demulsification of crude oil emulsions. Experiments were performed using ultrasonic baths operating at the following frequencies: 25, 35, 45, 130, 582, 862 and 1146kHz. Synthetic water-in-oil emulsions with 12%, 35% and 50% of water and medians of droplet size distribution (DSD, D(0.5)) of 5, 10 and 25μm were prepared using a heavy crude oil (API density of 19). Crude oil demulsification was achieved at frequencies in the range of 25–45kHz for all tested emulsions. When frequencies higher than 45kHz were applied, no changes in the characteristics of the crude oil emulsions were observed. Demulsification efficiencies of about 65% were achieved at a frequency of 45kHz after 15min of US application (emulsions with original water content of 50% and D(0.5)=10μm). An important aspect is that no addition of chemical demulsifiers was performed, and the demulsification efficiency was considered high, taking into account that the results were obtained using a non-conventional crude oil. Contrary to the normal application of low-frequency US that has been used for emulsification, the proposed approach seems to be a promising technology for water removal from crude oil emulsions.

Effect of Rheology Properties of Oil/Water Interface on Demulsification of Crude Oil Emulsions

Chemical demulsification is widely used in the petroleum industry to remove water from crude oil all over the world. In this work, the relationship between the rheological properties of oil/water interfacial film and demulsification of crude oil emulsions was investigated. The results showed that the elastic modulus was the critical factor for the dehydration ratio, the emulsions showed high dehydration ratio when demulsifiers reduced the elastic modulus of oil–water film to a certain extent (below 5 mN/m). Correlations between dehydration ratio and equilibrium interfacial tension, dynamic interfacial tension, and loss modulus were also investigated. The results showed no correlation between the interfacial tension (IFT), the loss modulus, and the dehydration ratio. However, correlations were observed between dynamic IFT, loss modulus, and demulsification speed when the demulsifier could reduce the elastic modulus of the oil–water film to <5 mN/m. The loss modulus was directly proportional to the surface ...

Effect of acidic returned fluid on the electric demulsification of crude oil emulsions

The electric demulsification of emulsions in acidic and basic conditions were studied. Two aggregation models of droplets were obtained.

Oil Removal from Oil-Water Emulsion by Electrocoagulation in a Cell with Rotating Cylinder Anode

The performance of a batch electrocoagulation cell (rotating cylinder electrochemical reactor) in the demulsification of crude oil emulsions was investigated. The cell used a rotating Al cylinder as anode and a stationary cylindrical screen of aluminum as cathode. Parameters studied are the current density, the NaCl concentration, initial pH, the anode rotation speed, initial oil concentration and the nature of the supporting electrolyte. Increasing the current density led to increasing the rate of de-emulsification; a current density of 11.4 mA/cm2 allowed complete separation in 10 minutes while a current density of 17.1 mA/cm2 allowed complete separation in 6 minutes. The optimum pH range for the electrocoagulation is 7–11, acidic media (pH 3–5) retarded the electrocoagulation. The increase in the concentration of the NaCl led to an increase in the rate of oil removal. Higher electrolyte conductivity of the emulsion increased the rate of oil removal. Anode rotation was found to have a strong effect in improving oil removal efficiency. The higher the initial concentration of the emulsion, the higher the rate of oil removal. NaOH was found to be the best electrolyte, followed by NaCl, then KCl and finally NH4Cl.

Improving the Demulsification Process of Heavy Crude Oil Emulsion through Blending with Diluent

In crude oil production from brown fields or heavy oil, there is production of water in oil emulsions which can either be controlled or avoided. This emulsion resulted in an increase in viscosity which can seriously affect the production of oil from sand phase up to flow line. Failure to separate the oil and water mixture efficiently and effectively could result in problems such as overloading of surface separation equipments, increased cost of pumping wet crude, and corrosion problems. Light hydrocarbon diluent was added in varied proportions to three emulsion samples collected from three different oil fields in Niger delta, Nigeria, to enhance the demulsification of crude oil emulsion. The viscosity, total petroleum hydrocarbon, and quality of water were evaluated. The viscosity of the three emulsions considered reduced by 38, 31, and 18%. It is deduced that the increase in diluent blended with emulsion leads to a corresponding decrease in the value of viscosity. This in turn enhanced the rate of demulsification of the samples. The basic sediment and water (BS&amp;W) of the top dry oil reduces the trace value the three samples evaluated, and with optimum value of diluent, TPH values show that the water droplets are safe for disposal and for other field uses.

Demulsification of Crude Oil Emulsion Using Propylene Oxide-Ethylene Oxide Block Copolymer

The effect of concentration, temperature and pH-value on the demulsification potency of the propylene oxide and ethylene oxide block copolymer initiated from alkylphenol formaldehyde resin in breaking up emulsion from Daqing oilfield have been investigated. The results revealed that demulsification potency of the studied demulsifier increases with the increase of demulsifier at low concentration, the increase of temperature, the increase of acidic pH-value and the increase of demulsification time, respectively. In the meantime, demulsification potency of the studied demulsifier decreases with the increase of demulsifier at high concentration and the increase of basic pH-value, respectively. Neutral pH-value of the emulsion was found to be the optimum value causing maximum demulsification potency.

Interfacial dilational rheology related to enhance oil recovery

Dilational rheology has been proved to be a powerful tool to investigate equilibrium and dynamic properties of adsorption films by recent studies. Interfacial dilational properties play crucial roles in Enhanced oil recovery (EOR) processes, such as the formation of oil bank and the demulsification of crude oil emulsions. Moreover, measurements of the interfacial rheology give important clues about the conformations and molecular interactions of amphiphiles adsorbed at an interface. In this review, the experimental results are summarized on dilational rheology of adsorbed layers containing surfactants and polymers employed in EOR, crude oil components and demulsifiers have been summarized. The relationship between dilational data and emulsion stability has been discussed.

Gemini Surfactant as a New “Green” Demulsifier for Treating Oilfield Emulsions

Surface tension and interfacial tension (IFT) were the key factors asso- ciated with the stability of crude oil emulsion. Investigation of interfacial tension behavior related with the demulsification of crude oil emulsions can have a great impact on the development of crude oil demulsification processes and products. This article presents the surface and interface behaviors of Gemini surfactants (12-2-12, (12)-2-(12), (14)-2-(14)). The results indicated that (12)-2-(12) could exhibit higher surface and interface active properties. The demulsification efficiency and related factors were also discussed. It showed that as an environmentally friendly and safer demulsifier, Gemini surfactant could exhibit better demulsification efficiency.

Demulsification of Crude Oil Emulsion via Ultrasonic Chemical Method

Lots of water and surfactants are poured into the oil well to enhance the exploiting efficiency, so the crude-oil emulsions exploited by this technology contain much water, which is very hard to be separated at present. The demulsifying and separating experiments of the crude-oil emulsion were conducted by using the thermal chemical method and the ultrasonic chemical method separately. The crude oil emulsion samples were provided by the Dagang oil field of China and the water content was 35% volume/volume (v/v). The key influencing factors on demulsification effect were explored by changing the ultrasonic output power, the irradiating time, and the demulsifier amount in the experiments. The dehydrating ratios were compared among the self-made emulsions of different water content with the ultrasonic chemical method. The demulsifying velocity and dehydrating ratio for the high water content crude-oil emulsion was better than that of the emulsion with lower water content in the demulsifying experiments with the ultrasonic chemical method. For the crude-oil emulsion used in this experiment, the result was a dehydrating ratio of 97.7% under the condition of 100 W of ultrasonic output power, 10 min of irradiating time, 50 mg/L of demulsifier, and 75°C of water bath temperature.

Demulsification of Crude Oil Emulsion Using Polyamidoamine Dendrimers

Six dendrimers with the same polyamidoamine (PAMAM) basic structure but different terminals/generations were synthesized by divergent method. The dendrimers were studied by surface tension measurement at the air‐water interface. The demulsification performance for oil/water (O/W) simulated crude oil emulsion and crude oil extract directly from field was investigated. The experimental results indicate that the three dendrimers terminated with ester groups were insufficient demulsifiers for crude oil emulsion. However, the three dendrimers terminated with amine groups exhibited excellent demulsification performance for O/W emulsions. As demulisifers, amine based dendrimers were superior to the commercial polyether ones (SP‐169 and BP‐169). The possible mechanisms for the nanocontainer effects of the dendrimers, through either surface adsorption or internal encapsulation, were discussed.

Effect of Salinity, Temperature, Water Content, and pH on the Microwave Demulsification of Crude Oil Emulsions

The main objective of this work is to investigate the effect of a set of crude oil emulsion variables, including pH and salt and water contents, upon the microwave demulsification process. A series of batch demulsification runs were carried out to evaluate the final emulsified water content of emulsion samples after the exposure to microwaves. Tests were performed at distinct heating temperatures, using water-in-heavy crude oil emulsion samples containing different salt and water contents and pH. Well-defined temperature programs were established to control the amount of energy applied to the emulsion and, ultimately, the viscosity. Higher microwave demulsification efficiencies were achieved for emulsions containing high water contents, except when high pH and salt contents were simultaneously involved.