Demulsifier Research Articles

Optimization of (RP6000 and MAKS-9150) demulsifiers for separation of water from (Kirkuk / baba, Khbbaz) crude oil emulsion

In this study oil-soluble (RP6000 and MAKS-9150) emulsion breakers have been selected for separation of water from Kirkuk / baba (50oC), Khbbaz (40oC) crude oil emulsions and their activity measured using the Bottle test method at different concentration and found the activity of RP6000 demulsified best than MAKS-9150 emulsion breakers. RP6000 separated water (100%) in (15)min., (40)ppm and in (60)min., (20)ppm of demulsified for Kirkuk/ baba Crude oil and for khbbaz Crude oil the (100%) water separation was in (15)min., (80)ppm and in (30)min., (60)ppm and PH effect, salinity, temperature and density of emulsion stability depending on literature were explained for Optimization.

Simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking

This paper describes the simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking. Extraction yields ranged from 94.9 for Ba to 109.8% for Fe. Simultaneous measurements were carried out at secondary lines of Ba, Co, Fe, and Ni. The limits of detection and quantification were, respectively, 3.819 and 1.146 mg L−1 for Ba, 2.274 and 7.421 µg L−1 for Co, 0.095 and 0.285 mg L−1 for Fe, and 2.138 and 6.614 µg L−1 for Ni. The precision ranged from 3.1 to 4.2%, 1.5 to 8.0%, 1.6 to 6.6%, and 0.4 to 6.1% for Ba, Co, Fe and Ni, respectively. The method accuracy was assessed by recovery tests and comparison of the results obtained by the proposed extraction method with those obtained after acid digestion. Recoveries ranged from 93.5 for Ni to 104.5% for Co.

Analytical extraction procedure combined with atomic and mass spectrometry for the determination of tin in edible oil samples, and the potential application to other chemical elements

Extraction induced by emulsion breaking was combined with graphite furnace atomic absorption spectrometry (GF AAS) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of tin in edible oil samples. Emulsion preparation was carried out by vortex agitation with Triton X-114 in diluted nitric acid. The emulsion breaking was reached by heating. Calibration curves were obtained by GF AAS and ICP-MS from 10 to 100 μg L−1 and from 0.1–10 μg L−1, respectively. The limits of detection were 1.1 and 0.009 μg L−1, respectively, and the limits of quantification were 3.6 and 0.03 μg L−1, respectively. Accuracy was assessed by spike and recovery tests and also by comparison with microwave-assisted acid digestion. The results obtained by both sample preparation methods were consistent for oil samples of olive, corn, and fish. In addition, the potential of the proposed analytical method was investigated for other 17 chemical elements.

Study of water-in-oil emulsions break of Brazilian oil using low-frequency ultrasonic chambers

Study of water-in-oil emulsions break of Brazilian oil using low-frequency ultrasonic chambers

Experimental study on EOR potential of water-in-oil emulsion via CO2/N2 triggered wormlike micelle solution

Oil in water (O/W) emulsion flooding appears to be an effective method to boost oil production of mature oilfields, while few works have been done to investigate the enhanced oil recovery (EOR) potential of water in oil (W/O) emulsion, especially in in-situ W/O emulsion. In the present work, a CO2/N2 triggered wormlike micelle solution (CO2-TWMS) for forming in-situ W/O emulsion was prepared firstly. Then, its CO2/N2 responsiveness was characterized through the change in viscosity and microstructure. Subsequently, the emulsifying ability of CO2-TWMS and the effect of CO2/N2 responsiveness on emulsion stability were investigated, followed by the study of oil displacement efficiency. Experimental results manifested that CO2 bubbling triggered the formation of wormlike micelles, which induced the formation of W/O or O/W/O emulsion under stirring condition. While N2 bubbling destroyed wormlike micelles and accelerated the breaking of emulsion. 0.5 pore volume (PV) CO2-TWMS flooding and sequent water flooding could significantly improve oil recovery of 20.7–31.9% in three-floor heterogeneous cores, which was mainly contributed to the enlargement in sweeping efficiency that caused by mobility ratio improvement of emulsion and Jamin effect of water droplets. The results from this study demonstrated that the CO2-TWMS has great potential for EOR in waterflooded heterogeneous reservoirs, which provides valuable insights for novel EOR technology that combined chemical flooding with CO2 capture.

Tar Removal from Gasification/Pyrolysis by Emulsion Liquid Membrane: A Short Overview

Tar is among undesirable by-products of producer gas generated from gasification/pyrolysis of biomass. Due to the erosive and corrosive characteristics of tar, a number of tar removal studies have been done. However, considering tar availability in deficient concentration, a highly selective and energy economics method is of importance. Emulsion liquid membrane is a choice of selective and economics method. Some studies on tar removal using emulsion liquid membrane were reported. Information about definition and transport mechanism of emulsion liquid membrane was given. Effects of emulsion formulation on tar removal were described. Effects of some operating conditions in permeation process on tar removal were also presented. The study found that types and concentration of surfactant and diluent as well as emulsification methods need to be properly considered for better result. Whereas permeation speed, volume ratio, and equipment used greatly affect the emulsion breaking and tar removal efficiency. Considering low emulsion breaking, application of Taylor-Couette column as the permeation equipment for further tar removal study is proposed.

Effect of Charge Density of Reverse Emulsion Breaker on Demulsification Performance for Steam-Assisted Gravity Drainage (SAGD) Emulsions under High Temperature and High Pressure

Reverse emulsion breakers (REBs) play a crucial role in the demulsification of complex water-in-oil-in-water (W/O/W) emulsions in steam-assisted gravity drainage (SAGD) production of oil sands. Developing effective REBs remains challenging due to the poor understanding of influencing factors and demulsification mechanisms. In particular, despite the recognition of the vital role of charge density of the REBs in their demulsification performance, the available literature is limited. Herein, we investigated the correlation between the charge density of commercial REBs and their demulsification performance for complex emulsions under simulated SAGD operation conditions (100–200 °C and 0.3–1.4 MPa) by employing an in-house-built bottle test system. It is demonstrated that a high charge density of the REBs not only promotes the qualities of produced water and oil but also significantly accelerates the speed of oil/water phase separation. At the microscale, the REB with a high charge density is capable of reducing the amount and size of residual oil droplets in produced water. The interactions of the species involved during the demulsification process were investigated by employing multiple techniques including optical microscopy imaging, ζ potential measurement, and dynamic light scattering. The results suggest that the cationic REBs are adsorbed at the oil/water interface, neutralize negative surface charge of oil droplets, and replace interface-active species originally present at the oil/water interface. Multilayer adsorption of REBs may be generated after demulsification, and the adsorbed REBs could partially desorb from the surface of oil droplets with increasing temperature. This work has delineated the influence of the charge density of REBs on their demulsification performance and improved the fundamental understanding of the interactions of the constituent species in SAGD emulsions and REBs, which provides useful information on the development and applications of efficient and cost-effective chemicals in oil sands exploitation and emulsion treatment.

Alkylacrylic-carboxyalkylacrylic random bipolymers as demulsifiers for heavy crude oils

This paper explains and analyses the process where two series of acrylic random bipolymers, based on alkyl acrylate/carboxyalkyl acrylate (KC) and alkyl acrylate/acrylic acid (KA), were prepared by means of emulsion polymerization technique. In both, the bipolymers’ monomers ratio was varied, while holding the more hydrophobic monomer in majority. The KC and KA bipolymers were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and size exclusion chromatography (SEC). Afterwards, demulsifying activity of the KC and KA bipolymers in two heavy crude oils was evaluated through bottle tests. According to the obtained results, the selection and determination of weight ratio of monomers have an important impact on the bipolymers efficiency to destabilize the water/crude oil emulsion. In both crude oils, KC bipolymer with a monomer ratio of K/C = 80/20 w/w showed the best demulsifying performance in comparison with KA bipolymer at the same weight ratio. Structure-activity parameters including partition coefficient (Log P), hydration energy (HE), molar refractivity (MR), and polarizability (α) were calculated for both bipolymers. The destabilization effectiveness of bipolymers of the water/crude oil interface was found to be related to the partition coefficient (Log P), which indicated a strong diffusion capacity of the bipolymer to traverse through the oil phase and destabilize the water/oil interface. Furthermore, higher values of molar refractivity and polarizability are preferable for higher water removal efficiency (WRE). Moreover, the structure–activity parameters, as well as the quantum parameters, specific characteristics of acrylic bipolymers and some physicochemical properties of the crude oil were deployed in the process to predict the water removal efficiency. E2 equation which accomplished the external validation acted as the resultant of the two equations, E1 and E2, that fulfilled the restriction for the internal validation of Q2 > 0.6. Predictive squared correlation coefficients (QF12,QF22, and QF32) and external validation metric parameter (rm2) were calculated based on E2. Consequently, the new alkylacrylic-carboxyalkylacrylic bipolymers, insusceptible to acid environment, showed significantly improved properties as emulsion breakers, drop coalescers, and clarifiers.

Molecular modeling and experimental testing on the comparative performance of macrocyclic and linear zwitterionic surfactants for the emulsified heavy oil recovery

One of the major problems in heavy oil recovery in Mexican carbonate reservoirs is related to the formation of highly stable and viscous water-in-oil emulsions, which impacts on decreasing in hydrocarbon production. This fact is derived from the presence of high amounts of asphaltenes in the oil, as well as from the high concentrations of divalent ions in the formation water. In order to develop a technological solution for this problem, in this work a theoretical/experimental methodology is presented, which allows the development of new surfactants with multifunctional capabilities, such as changes in rock wettability, interfacial tension and emulsion breaking up. The molecular modeling is used to study emulsions formation, as well as the demulsifying capability of two kinds of surfactants: branched geminal zwitterionic liquids and new zwitterionic macrocyclic oxo-aza-crown ethers. Spontaneous-imbibition studies were carried out in order to determine the capacity of these surfactants to increase the oil recovery factor. Both theoretical and experimental parts show that the new macrocyclic surfactants presented a better performance than the branched germinal zwitterionic surfactants, therefore, they constitute a potential technological solution to increase oil recovery factor in the mentioned reservoirs. Their emulsion breaking up capacity, allows to extract oil from the porous media and avoids formation of new emulsions in the extraction process.

Research progress on hydrate plugging in multiphase mixed rich-liquid transportation pipelines

The plugging mechanism of multiphase mixed rich-liquid transportation in submarine pipeline is a prerequisite for maintaining the fluid flow in the pipeline and ensuring safe fluid flow. This paper introduced the common experimental devices used to study multiphase flow, and summarized the plugging progress and mechanism in the liquid-rich system. Besides, it divided the rich-liquid phase system into an oil-based system, a partially dispersed system, and a water-based system according to the different water cuts, and discussed the mechanism of hydrate plugging. Moreover, it summarized the mechanism and the use of anti-agglomerates in different systems. Furthermore, it proposed some suggestions for future research on hydrate plugging. First, in the oil-based system, the effect factors of hydrates are combined with the mechanical properties of hydrate deposit layer, and the hydrate plugging mechanism models at inclined and elbow pipes should be established. Second, the mechanism of oil-water emulsion breaking in partially dispersed system and the reason for the migration of the oil-water interface should be analyzed, and the property of the free water layer on the hydrate plugging process should be quantified. Third, a complete model of the effect of the synergy of liquid bridge force and van der Waals force in the water-based system on the hydrate particle coalescence frequency model is needed, and the coalescence frequency model should be summarized. Next, the dynamic analysis of a multiphase mixed rich-liquid transportation pipeline should be coupled with the process of hydrate coalescence, deposition, and blockage decomposition. Finally, the effects of anti-agglomerates on the morphological evolution of hydrate under different systems and pipeline plugging conditions in different media should be further explored.

EMULSION LIQUID MEMBRANE FOR HEAVY METALS REMOVAL: EMULSION BREAKING STUDY

Emulsion liquid membrane (ELM) method has been widely applied in the separation process as the alternative of liquid/liquid extraction. This study compared the application of microwave, ultrasonic probe, and centrifuge in breaking the used emulsion. Demulsification efficiency was investigated in term of water content in the membrane phase solution before and after demulsification. The results showed that the use of microwave to break the used emulsion provided demulsification efficiency of 98.10%, while application of ultrasonic probe was able to break emulsion at efficiency of 98.45%. In the meantime, demulsification efficiency of almost 97% was achieved when employing centrifuge at centrifugation speed of 3000 rpm. Considering the energy consumption, it is recommended to apply microwave irradiation for emulsion breaking. It could save energy up to 97% and 99% compared to that of ultrasonic probe and centrifuge, respectively.

Chemical Destabilization of Fresh and Spent Cutting Oil Emulsions: Differences between an Ecofriendly and Two Commercial Synthetic Lubricants

The aim of this study was to evaluate if eco-friendly lubricants had an additional advantage over conventional synthetic lubricants in terms of emulsion treatment of metalworking wastewater. To these purpose, two fresh commercial synthetic cutting oil emulsions were compared with an emulsion obtained from a new cutting oil produced from the reuse of slaughtering waste (CADT-605 from Kimya Srl, Bari, Italy). The breaking of the fresh emulsions was carried out with the addition of small amounts of sulfuric acid (2–20 mL/L) followed by pH neutralization by means of calcium hydroxide. During the two-step treatments, COD, BOD5 and non-ionic surfactant (NIS) concentrations were monitored in the aqueous phase. The results demonstrated that the best results were obtained with the emulsion produced with the bio-based lubricant. In addition, this cutting oil was tested in a metalworking plant within 30 days and the resulting spent emulsion was treated with the proposed process. In all the cases, the treatment led to a drastic decrease of the COD, BOD5 and NIS contents that allow the discharge of resulting aqueous phase in sewers or in surface water bodies, together with the other wastewater produced by the plant, in agreement with the Italian regulation.

Oxidation-Responsive Emulsions Stabilized by Cleavable Metallo-Supramolecular Cross-Linked Microgels.

An original route to develop an advanced class of microgel emulsifiers containing stimulable metallo-supramolecular instead of frozen covalent cross-links is reported. The poly(N-isopropylmethacrylamide) (PNiPMAM) chains of the microgel are connected by iron(II)-bis(terpyridine) coordination supramolecular complexes that can be cleaved on demand, leading to unique properties both at interfaces and in volume. The microgel synthesis is not demanding, and the characterization of its supramolecular structure can be precisely achieved by standard methods. Singularly, interfaces of an oil-in-water emulsion stabilized by the supramolecular particles can be triggered at the molecular scale by oxidation of Fe(II) to Fe(III), leading to emulsion breaking. In bulk, we show that a microgel dispersion can indeed be transformed into a polymer solution upon oxidation. Our study paves the way to the discovery of unusual microgel properties as our proof-of-concept can be extended to different supramolecular chemistry and architecture.

Experimental Investigation on Separation Behavior of Heavy-Oil Emulsion for Polymer Flooding on Alaska North Slope

Summary The first-ever field pilot on Alaska North Slope (ANS) to validate using polymer floods for heavy-oil enhanced oil recovery is currently ongoing. One of the major concerns of the operator is the effect of polymer on oil/water-separation efficiency after polymer breakthrough. This work investigates the influence of polymer on the separation behavior of heavy-oil emulsions and evaluates the performance of emulsion breakers (EBs). In this study, two types of heavy-oil emulsions were prepared and tested at 20 and 50% water cut (WC), respectively. The bottle test method was used in the experiments, in which the separated water volume with time, the separated water quality, and the volume fraction of phases were recorded. Results showed that polymer accelerated the oil/water separation acting as an emulsion inhibitor at 20% WC but tended to impede the water separation at 50% WC. Regardless of WC, polymer resulted in poor water quality and the formation of a stable intermediate oil in water (o/w) emulsion, because of the increased viscosity of the water phase. The performance of EBs showed a complex dependency on the WC, the type of demulsifier and dosage, and the polymer concentration. Despite the varied conditions encountered in the heavy-oil/water/polymer/demulsifier system, a compound EB achieved satisfactory demulsification performance, showing the highest potential for deployment in the current ANS polymer flooding pilot. In this paper, we systematically studied the potential influence of polymer breakthrough on the separation behavior of heavy-oil emulsion on ANS for the first time. The findings of this study will provide practical guidance in advance for produced fluid treatment of the ongoing first-ever polymer flooding pilot on ANS.

A novel cold biorefinery approach for isolation of high quality fish oil in parallel with gel-forming proteins.

The pH-shift process for isolation of gel-forming proteins from fish processing by-products was extended to allow parallel isolation of fish oil. Subjecting the floating emulsion layer formed during pH-shift processing of salmon by-products to pH-adjustment or freeze/thawing efficiently released the emulsified oil at 4°C. However, for herring by-products higher temperature (10°C) and a combination of the emulsion-breaking techniques was required for efficient oil release. Oil recovery yield using the adjusted pH-shift process was lower than with classic heat-induced oil isolation (90°C/20min), but pH-shift-produced oils had higher amounts of n-3 polyunsaturated fatty acids (n-3 PUFA). Also, alkaline pH-shift processing produced oils with remarkably less oxidation products and free fatty acids compared with acid pH-shift process or heat-induced isolation. Extending the pH-shift process with emulsion breaking techniques can thus be a promising biorefinery approach for parallel cold production of high-quality fish oil and gel-forming proteins from fish by-products.

D-optimal mixture design for the optimization of extraction induced by emulsion breaking for multielemental determination in edible vegetable oils by microwave-induced plasma optical emission spectrometry

A sample pretreatment based on an extraction process by emulsion breaking for multi-element determination in edible oils was developed. The determination of eight trace elements (Al, Ba, Cu, Cr, P, Ni, Ti, and Zn) was carried out by microwave-induced plasma optical emission spectrometry (MIP OES) after the extraction procedure. A D-optimal mixture experimental design was used to obtain the best experimental conditions for the extraction induced by emulsion breaking (EIEB). The proportion of HNO3 solution, Triton X-100 solution and sample was evaluated in a multivariate manner. The best recovery efficiency was obtained with 1.0 mL of 30% (v/v) HNO3, 1.0 mL of 30% (w/v) Triton-X 100 and 3.0 mL of the sample. The precisions, established as the relative standard deviation (RSD, %), were better than 2.5% for all analytes. The developed method was applied to the analysis of commercial vegetable oils with low limits of detection and good precision.

Extraction induced by emulsion breaking for simultaneous determination of Co, Fe and Ni in petroleum asphalt cement by high-resolution continuum source atomic absorption spectrometry

This paper reports, for the first time, the simultaneous determination of Co, Fe and Ni in petroleum asphalt cement by high-resolution continuum source atomic absorption spectrometry after extraction induced by the emulsion breaking method. The variables that could influence the sample preparation were evaluated, like sample dilution with toluene and mineral oil, extraction time, HNO3 and Triton X-100 concentration in the aqueous extractant solution. At optimized conditions, 0.08 g of the sample was dissolved with 1.5 mL of toluene and 3.5 mL of mineral oil and vigorous mixed with the extractant solution containing 40% (v/v) of HNO3 and 40% (v/v) of Triton-X-100. The emulsions were broken by heating just after their formation and the aqueous extracts were collected for analysis. Simultaneous determination was carried out at the secondary lines of Co (352.685 nm), Fe (352.604 nm) and Ni (352.454 nm). For this purpose, the best pyrolysis and atomization temperatures were 700 and 2400 °C, respectively. Calibration was performed with standard aqueous solutions and no matrix effects were observed. The limit of detection was 0.003 mg L−1 for Co, 0.018 mg L−1 for Fe and 0.027 mg L−1 for Ni. Method accuracy was confirmed by comparing the results obtained by the proposed extraction method with those obtained after samples acid digestion. Recoveries ranged from 100 to 107%, 103 to 109% and 95.5 to 98.9% were obtained for Co, Fe and Ni, respectively.

Recent Advances of Surfactant-Polymer (SP) Flooding Enhanced Oil Recovery Field Tests in China

Recently, there are increasing interests in chemical enhanced oil recovery (EOR) especially surfactant-polymer (SP) flooding. Although alkali-surfactant-polymer (ASP) flooding can make an incremental oil recovery factor (IORF) of 18% original oil in place (OOIP) according to large-scale field tests in Daqing, the complex antiscaling and emulsion breaking technology as well as potential environment influence makes some people turn to alkali-free SP flooding. With the benefit of high IORF in laboratory and no scaling issue to worry, SP flooding is theoretically better than ASP flooding when high quality surfactant is available. Many SP flooding field tests have been conducted in China, where the largest chemical flooding application is reported. 10 typical large-scale SP flooding field tests were critically reviewed to help understand the benefit and challenge of SP flooding in low oil price era. Among these 10 field tests, only one is conducted in Daqing Oilfield, although ASP flooding has entered the commercial application stage since 2014. 2 SP tests are conducted in Shengli Oilfield. Both technical and economic parameters are used to evaluate these tests. 2 of these ten tests are very successful; the others were either technically or economically unsuccessful. Although laboratory tests showed that SP flooding can attain IORF of more than 15%, the average predicted IORF for these 10 field tests was 12% OOIP. Only two SP flooding tests in (SP 1 in Liaohe and SP 7 in Shengli) were reported actual IORF higher than 15% OOIP. The field test in Shengli was so successful that many enlarged field tests and industrial applications were carried out, which finally lead to a commercial application of SP flooding in 2008. However, other SP projects are not documented except two (SP7 and SP8). SP flooding tests in low permeability reservoirs were not successful due to high surfactant adsorption. It seems that SP flooding is not cost competitive as polymer flooding and ASP flooding if judged by utility factor (UF) and EOR cost. Even the most technically and economically successful SP1 has a much higher cost than polymer flooding and ASP flooding, SP flooding is thus not cost competitive as previously expected. The cost of SP flooding can be as high as ASP flooding, which indicates the importance of alkali. How to reduce surfactant adsorption in SP flooding is very important to cost reduction. It is high time to reevaluate the potential and suitable reservoir conditions for SP flooding. The necessity of surfactant to get ultra-low interfacial tension for EOR remains further investigation. This paper provides the petroleum industry with hard-to-get valuable information.

Demulsification and breaking mechanism of variable quartz concentrates obtained from sand

This study reports the efficacy of quartz particles extracted from sand for the destabilization of crude oil emulsions and efficient water removal. Demulsification performance of quartz concentrates obtained from stacked sieves with openings: 75, 125, 250 and 300 μm and quartz quantity varying from 1% to 7% were investigated using the bottle test technique at a temperature of 90 °C. The breaking mechanism of emulsion driven by quartz was analyzed by rheology, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), optical microscopy and scanning electron microscopy (SEM). Experimental results showed that the quartz concentrates generated from stacked sieves: 75, 125, 250, and 300 μm had optimal demulsification efficiency (DE) of 98%, 98%, 99%, and 99%, respectively. Moreover, the quartz concentration needed to attain these DEs levels ranges from 3 to 5%. In addition, the performance of quartz as a demulsifier was compared with a commercial demulsifier (ethyl cellulose). Viscosity versus time measurements demonstrated the change in emulsion's viscosity before and after quartz addition. A drastic reduction in the emulsion's viscosity was observed after quartz addition, indicating rupture and coalescence of water droplets. The FTIR and XRD analysis buttressed the functional groups and structural pattern while optical microscope and SEM analysis exhibited the morphology of quartz particles before and after the demulsification processes. A mechanism elucidating the breaking of crude oil emulsion by quartz is proposed. The results indicated that quartz particles processed from the sand will be useful as demulsifiers in the petroleum industry.

Understanding the effect of skim oil recycle on the water/oil separation in steam assisted gravity drainage operations

In steam assisted gravity drainage (SAGD) operations, skim oil recycled to a free water knockout (FWKO) often results in poor water quality and rag formation at the oil/water interface. To improve water quality and demulsification efficiency in the presence of skim oil recycle, it is necessary to understand the status of oil and solids in the produced water throughout the process. In this paper, the effect of skim oil on the water/oil separation in SAGD operations was studied. Dynamic optical fluid imaging (DOFI) technology was used to characterize oil and solids concentrations, oil droplet sizes, and the associated size distributions in the produced water collected from various vessels in a SAGD process. The DOFI analyses show that skim oil recycle caused more oil and solids to be sent to the FWKO, treater and induced gas flotation (IGF) outlet waters and finally to oil removal filters (ORF). The increased oil in water led to more oil droplets, especially more numerous small oil droplets remaining in the produced water. These small oil droplets are more challenging to remove than larger oil droplets, resulting in deteriorated water quality. Skim oil recycle decreased the oil removal efficiency of the IGF vessel and increased fouling of ORF filters by oil and solids. Fourier transform infrared spectroscopy analysis of the solids collected from the produced water in the presence of skim oil recycle indicated that the solids are bitumen-coated fine quartz and clays. Demulsification studies show that application of dual reverse emulsion breakers could help improve water quality and alleviate the negative effects due to the solids from skim oil addition.