Heavy Crude Oil Emulsions Research Articles

A Comparative Study on Droplet Coalescence in Heavy Crude Oil Emulsions Subjected to Microwave and Ultrasonic Fields

In the world of fossil fuels, crude oil is an indispensable source of energy. During the transportation and processing of oil, water-oil emulsions are frequently created. The traditional methods of eliminating these emulsions are based on utilization of high heat, chemicals, and electrical energy to force the emulsion to separate into water and hydrocarbon phases. Recently, microwave and ultrasonic waves have been successfully tested for demulsification of water-oil emulsions. When emulsion is exposed to the microwave field, molecular rotation and ionic conduction cause internal heating due to penetration of electromagnetic waves into the emulsion, resulting in accelerated emulsion separation. Exposing the emulsion to the ultrasonic field causes the water droplets to migrate to pressure nodes of standing ultrasonic wave under the influence of the primary acoustic force. Further coalescence of droplets is due to attractive secondary interdroplet acoustic forces. Two trajectory models are developed to predict the relative motion of water drops subjected to the microwave and ultrasonic fields. The results show that the coalescence under the microwave field is considerably much faster than the coalescence under the ultrasonic field.

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&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.

Investigation of Paenibacillus alvei ARN63 ability for biodemulsifier production: Medium optimization to break heavy crude oil emulsion

The demulsifying performance of Paenibacillus alvei ARN63 (P. alvei), as a biodemulsifier-producing bacterium, for breaking water-in-heavy crude oil emulsion has been investigated. The produced lipopeptide biodemulsifier showed the potential to be used in the petroleum industry as an environmentally friendly and non-toxic material. To optimize the biodemulsifier production, the impacts of parameters such as temperature, pH, carbon source and carbon concentration at a constant agitation speed of 180rpm and with ammonium sulfate as the sole nitrogen source (1.0g/l) were studied in detail. Several normal paraffin compounds, vegetable oils and motor oil revealed the ability to be used as the carbon source for synthesis of biodemulsifier. The best biodemulsifier production was obtained employing motor oil as the carbon source with a concentration of 42.5g/l at 37°C and pH 7.0 after 72h of incubation. Under these conditions, the surface tension of the medium reduced from 58mN/m to 24.7mN/m and the biodemulsifier yield reached a value of 2.1g/l. The demulsification ratio approached 77% and the produced biodemulsifier by P. alvei strain effectively broke water-in-heavy crude oil emulsion. According to biodemulsifier production and growth time course profiles, the biosynthesis was growth associated. Besides, the produced biodemulsifier had good stability during exposure to salinities up to 20%, temperatures up to 80°C and a wide pH range of 2–12.

Application of Physico-technological Principles in Demulsification of Water-in-crude Oil System

The presence of water-in-oil emulsion in petroleum industry presents serious pipeline challenges and flow problems such as corrosion, scaling and plugging of in-field flow lines plugging. These problems are attributed to the presence of asphaltene and resinous compounds in the crude oil. Application of a suitable approach for the treatment of crude oil emulsion remains a major concern in the petroleum industry. This paper discusses the use of light gasoline as diluents to reduce the viscosity of a 17° API heavy crude oil emulsion. Several demulsification bottle tests were carried out. Addition of up to 25ml of gasoline led to an increase in API gravity of the crude oil from 17 to 24, indicating improved crude quality. The results also show increased water separation in response to corresponding increase in gasoline blending ratios which was most effective at gasoline blends between 5ml and 10ml. The crude oil and gasoline blend samples dosed with 2ppm of demulsifier chemical, NALCO EC2111A, a reduced injection rate from 5ppm, currently used on the operator's oilfield showed considerably higher rates of water separation with huge savings in demulsifier costs.

Application of Physico-Technological Principles in Demulsification of Water-In-Crude Oil System

The presence of water-in-oil emulsion in petroleum industry presents serious pipeline challenges and flow problems such as corrosion, scaling and plugging of in-field flow lines plugging. These problems are attributed to the presence of asphaltene and resinous compounds in the crude oil. Application of a suitable approach for the treatment of crude oil emulsion remains a major concern in the petroleum industry. This paper discusses the use of light gasoline as diluents to reduce the viscosity of a 17o API heavy crude oil emulsion. Several demulsification bottle tests were carried out. Addition of up to 25ml of gasoline led to an increase in API gravity of the crude oil from 17 to 24, indicating improved crude quality. The results also show increased water separation in response to corresponding increase in gasoline blending ratios which was most effective at gasoline blends between 5ml and 10ml. The crude oil and gasoline blend samples dosed with 2ppm of demulsifier chemical, NALCO EC2111A, a reduced injection rate from 5ppm, currently used on the operator’s oilfield showed considerably higher rates of water separation with huge savings in demulsifier costs. Keywords: Demulsifier, emulsion, viscosity, gasoline, diluents

Flow properties of water-in-North Sea heavy crude oil emulsions

In the present research, rheological and pipeline flow properties of North Sea heavy crude oil emulsions (w/o) were investigated using a stress-controlled rheometer and lab scale flow rig. The rheological properties of the emulsions were studied at different aqueous phase volume fractions (ϕ) from 0.0 to 0.70, temperatures from 20°C to 50°C, and shear rates from 0.1s−1 to 1000s−1. The rheology measurements indicate the crude oil and emulsions exhibit strong shear thinning at low temperatures and the power law fits quite well the rheology data of the crude oil as well as emulsions. Viscosities of the emulsions were determined from the rheograms at different shear rates and temperatures and modeled successfully using the Pal and Rhodes viscosity equation. Droplet size distributions measured using the Nuclear Magnetic Resonance (NMR) and digital video microscopy (DVM) techniques indicate the emulsions have an average droplet size of around 3–4μm. The pipeline flow properties of the emulsions were investigated in a 3m horizontal test section of pipe with 0.0221m inner diameter using the lab scale flow rig at different aqueous phase volume fractions from 0.0 to 0.50 and flow rates from 0.10m/s to 0.70m/s for 50°C. The pipeline flow measurements indicate the pressure gradients (ΔP/L) in the pipeline increase as a function of aqueous phase volume fraction and flow rate and water and North Sea heavy crude oil flows are not fully dispersed at aqueous phase volume fractions above 0.10.

Tweens demulsification effects on heavy crude oil/water emulsion

The demulsification role of Tweens (nonionic polymers) was determined in the separation of water from heavy crude oil emulsion. According to the previous researches, these nonionic polymers, having hydrophilic and lipophilic groups, are appropriate for making oil in water emulsion. In this research their effects in certain concentrations on demulsifying of water in crude oil emulsion were proved. High molecular weight, alkenes’ chains and groups of ketone and ester in these polymers can improve their performance for the demulsification of water in crude oil emulsion. Their efficiencies are improved with electronegative groups such as oxygen. They leave no corrosion effect because they are neutral and do not leave counter ions.

Destabilization of Heavy and Light Crude Oil Emulsions via Microwave Heating Technology: An Optimization Study

Destabilization of Heavy and Light Crude Oil Emulsions via Microwave Heating Technology: An Optimization Study

Separation of Heavy Crude Oil Emulsions Using Microwave Radiation for Further Crude Oil Analysis

Microwave radiation in closed vessels was used for the separation of heavy crude oil emulsions for further oil characterization. Operational conditions were studied and the following parameters were evaluated: water content, density, viscosity, N, S, V, Ni, and Cl. Using the proposed procedure it was possible to reduce the water and Cl content in crude oil to values lower than 1% and 300 µg g−1, respectively. It was possible to determine important crude oil properties without interferences caused by excessive water and salt concentrations. The proposed procedure is relatively fast and it was possible to obtain a suitable condition for water and salt removal from heavy crude oil emulsions without using demulsifiers or toxic reagents.

Emulsions of Heavy Crude Oils. II. Viscous Responses and Their Influence on Emulsion Stability Measurements

The stability of 30 heavy crude oil emulsions was studied in a parallel-plate laboratory coalescer (DC field). Particularly, viscous responses and their influence on the emulsion stability measurements were investigated. In addition to highlighting previous results from the same experimental setup and discussing these based on recent experience, new results at different temperatures and volume fractions of water were presented. A new semi-empirical model for the characteristic time of the destabilization process was presented. The electrical forces were modelled with a point-dipole approximation and the hydrodynamic resistance to droplet transport was modelled with an empirical term including the logarithmic viscosity of the oil phase. The new model clearly performed much better than the previous model, particularly for very viscous crude oils. Studies of the performance of industrial electrocoalescers have showed that simple electrostatic theory can potentially explain complex separation phenomena when the resistance to the coalescence step is reduced by an efficient demulsifier. The ultimate goal is to build a model for both the laboratory setup and the industrial coalescer so that laboratory experiments can be used to predict the behavior of the industrial process.

Emulsification of heavy crude oil in water for pipeline transportation

The stability and viscosity of W/O emulsions and their application for heavy oil pipeline transportation were investigated using two Iranian crude oil samples. An Iranian heavy crude oil sample named West Paydar and a blend of diesel and bitumen were used to produce heavy crude oil emulsions in water. The diverse factors affecting the properties and stability of emulsions were investigated. There was a restricted limit of 60 vol.% for crude oil content in the emulsions, beyond that limit the emulsions were inverted to water-in-oil emulsions. Different crude oil-in-water emulsions were prepared through addition of Triton X-100 surfactant. According to performed investigations, emulsification reduces the viscosity of the crude oil samples. However the viscosity of the emulsions increased by increasing the oil content of the emulsion, surfactant concentration, speed and time of mixing, salt concentration, and pH of the aqueous phase, while temperature of homogenization process substantially reduced the viscosity of the prepared emulsion. The stability of crude oil-in-water emulsions decreased by increasing the oil content while increasing the surfactant concentration, time and speed of mixing, pH of the aqueous phase and temperature enhanced the emulsion stability. The stability of crude oil emulsions was also increased by increasing the salt concentration. The main applicable observation of this research is that heavy crude oil-in-water emulsions can be highly stabilized simply by increasing the pH of the aqueous phase to basic values.

Microwave-Assisted Procedure for Salinity Evaluation of Heavy Crude Oil Emulsions

A procedure for salt extraction of heavy crude oil emulsions (API lower than 14°) was performed using microwave radiation. Emulsion was transferred to high-pressure quartz vessels with further water addition. Microwave radiation was applied for 60 min, and after separation of phases, chloride determination was performed in the water phase by ion chromatography (IC). The sampling procedure, heating time (10−40 min), microwave power (500−800 W), and the number of extractions (1−5) were evaluated. The salt remaining in the oil phase was determined, as chloride, by IC after sample digestion by a microwave-induced combustion technique, and the results confirmed the high efficiency of the proposed microwave-assisted salt extraction procedure. Using the proposed procedure, the salt extraction efficiency from heavy crude oil emulsion was higher than 95%. For a comparison of the results, Cl determination was also performed by inductively coupled plasma−optical emission spectrometry and potentiometric titration. The procedure allowed the salinity determination in less time (1 h) in comparison to the recommended ASTM D 6470 method (more than 4 h), and the use of toxic reagents or demulsifiers was avoided. Up to eight samples could be processed simultaneously, making the proposed procedure suitable for routine analysis in a laboratory scale.

Demulsification of Extra Heavy Crude Oil

The demulsification of orimulsion, an extra heavy crude oil, was studied by a PDY-1 instrument of electric demulsification. Some commercial demulsifiers, including P, RN, and RB series demulsifiers, were tested; however, their dewatering efficiency was unsatisfactory. ZQ series demulsifiers were synthesized and applied. It is pointed out that the ZQX3 series demulsifier had satisfactory dewatering ability for extra heavy crude oil emulsion. In order to improve the dewatering efficiency, toluene diisocyanate (TDI) was used as a chain extender to modify the ZQ series demulsifiers and an assistant—ammonium sulfate (t1)—was added. The results indicate that the dewatering efficiency of ZQ43 and a t1 mixture reaches excellent dewatering efficiency.

The viscoplastic properties of crude oil–water interfaces

The breaking of water-in-crude oil emulsions is a major challenge in the conventional petroleum industry, while oil-in-water emulsions present similar issues in commercial oilsands extraction processes. The stability of these emulsions can be attributed to complex rheological properties of the crude oil–water interface. Novel micromechanical techniques are developed that allow direct measurements of interfacial behaviour of emulsion drops. In these techniques, individual emulsion drops are elongated using micropipettes, where one micropipette is shaped into a cantilever for force measurements. As such, the surface behaviour of a drop is recorded in stress–strain experiments. In an alternative technique, the extended drop is released from a micropipette, and its natural, tension-driven relaxation is observed. The surface behaviour of bitumen (a heavy crude oil) emulsion drops in aqueous environments, that include dissolved calcium ions and suspended montmorillonite clays, is studied. The plasticity and other surface properties of these bitumen drops are discussed. A simple, lumped-parameter model is developed to describe the recovery of a bitumen drops to their final non-spherical shapes.

Emulsions of Heavy Crude Oils. I: Influence of Viscosity, Temperature, and Dilution

Twenty‐seven crude oils of different origin have been systematically analyzed with regard to viscosity, density, molecular weight, and SARA (saturates, aromatics, resins, asphaltenes) fractionation. Emulsion stability of water‐in‐oil emulsions of the different crude oil samples have been measured by the critical electric field technique (E‐critical). In addition, droplet size distributions for some of the water‐in‐oil emulsions have been determined by NMR self‐diffusion. Rheology measurements show that some of the crude oils have Bingham plastic type flow behavior at temperatures below 20°C, indicating content of waxes. Analysis of the critical electric field measurements shows that the E‐critical value depends on the applied electric field gradient. At low applied electric field gradients, the droplets are given more time to organize into water‐continuous bridges, resulting in a lower E‐critical value than when the applied electric field gradient is higher. The value of E‐critical also increases as the volume of the water phase decreases, due to the increased distances the droplets must move to form linear chains between the two electrodes. E‐critical measurements of emulsions of diluted crude oils show that, in general, the emulsion stability decreases with increased dilution of the oil phase. However, some systems show regions where the emulsion stability is independent of the dilution ratio or viscosity of the crude oil. Here the coalescence rate controls the level of emulsion stability. Viscosity and emulsion stability for water‐in‐oil emulsions were measured for the complete crude oil matrix (27 crude oils), and in general there is an increase of the emulsion stability as the viscosity increases. However, viscosity also correlates well with the SARA data of the crude oils. E‐critical shows a temperature dependence according to the Arrhenius law.

Pipeline Flow of Heavy Crude Oil Emulsions

Abstract Using a 53 mm test pipeline, emulsions containing up to 67% Lloydminster heavy crude oil in water have been transported in laminar and turbulent flow. Pressure drops, droplet size distributions, viscometry and velocity distribution measurements were made. The results showed that a homogeneous model was appropriate for emulsions with median droplet sizes near 30 microns. Introduction Pipeline flow of oil in water emulsions occurs widely in field operations and has also been studied systematically in laboratory conditions. Zakin et al.(1), used oils with specific gravities between 0.78 and 0.923 in emulsions formed in a colloid mill. The emulsions were non-Newtonian at oil concentrations of 50% by weight and above. Turbulent flow pressure drops were between 8% and 26% lower than values predicted using their laminar flow behaviour. These predictions used the Dodge and Metzner(2) correlation for turbulent non-Newtonian friction which has been largely supplanted by those of Wilson and Thomas(3) and Thomas and Wilson(4). Pal and Rhodes(5) used a mineral oil of comparatively low viscosity and inferred effective viscosities from the laminar and turbulent flow pressure gradients, assuming Newtonian fluid behaviour. With 45% and 55% oil in water emulsions, laminar flow effective viscosities were significantly lower than those in turbulent flow. The droplet size was unknown, however. With heavy crudes, inversion(6,7) of an oil-in-water emulsion to a water-in-oil emulsion can occur during pipeline flow with a catastrophic increase in pipeline pressure drop if the oil wets the pipe wall. On the other hand Layrisse et al.(8), found stable emulsions for a wide range of concentrations (to 65% oil) and shear rates with droplets whose mean diameters ranged between 6 and 86 ?m. Good agreement was found between viscosities inferred from pipeline pressure drops and values measured with Couette viscometers. The rheology was strongly dependent on droplet size, however, and non-Newtonian behaviour was evident for smaller diameters, low shear rates and high oil concentrations. Turbulent flow pressure drops appeared to be within 20% of the predicted values. In contrast with these results, Wyslouzil et al.(9), found pipeline pressure drops to be significantly lower than values predicted using measured viscosities, in both the laminar and turbulent flow regions. The disparity was attributed to droplet migration away from the wall, producing a region of depleted concentration. With prolonged recirculation in a closed loop, an instability occurred which resembled the inversion reported by Gillies et al.(6) The initial droplet size in the Wyslouzil experiments was in the range of 5 – 10 µm. Gillies and Shook(7) have reported experiments conducted with high oil concentrations in laminar pipe flow. Differences between the apparent viscosities in pipe flow and those measured in a Couette viscometer were also attributed to droplet migration and evidence for this was obtained in the form of velocity distributions measured with a pitot tube. In contrast with the droplets in the Wyslouzil et al. experiments, the droplets were too large to allow their diameters to be determined photographically.

Biosurfactant production by two isolates ofPseudomonas aeruginosa

Two strains of biosurfactant-producing bacteria, identified asPseudomonas aeruginosa, were isolated from injection water and crude oil-associated water in Venezuelan oil fields. Both biosurfactants resembled rhamnolipids and produced stable emulsions of heavy and extra-heavy crude oils, reducing the surface tension of water from 72 to 28 dynes/cm. Tenso-active properties of the biosurfactants were not affected by pH, temperature, salinity or Ca(2+) or Mg(2+) at concentrations in excess of those found in many oil reservoirs in Venezuela.

Studies of Water-Continuous Emulsions of Heavy Crude Oils Prepared by Alkali Treatment

Summary Pumping of heavy crudes as concentrated oil-in-water (O/W) emulsions may be a feasible pipeline transport scheme for viscous crudes. Many crude oils can be emulsified by treatment with alkali without the addition of expensive surfactants. In experimental studies of seven crudes, stable emulsions could be formed with four by alkali treatment; two could not be emulsified; and one formed unstable emulsions. High shear viscosity, particle size, and stability measurements on 60% emulsions formed with various amounts of alkali are reported. High shear viscosities below 100 mPa·s [100 cp] at 25°C [77°F] indicate that concentrated emulsions of some crudes can be transported in pipelines at concentrations of 60% and higher.

Slurries and emulsions of waxy and heavy crude oils for pipeline transportation of crude oil

The high viscosity of many asphaltic crude oils and the high pour points of many waxy crude oils present significant problems in their transportation over long distances by pipeline and tanker. While heating the oils and insulating the pipelines will help alleviate the problem, there is danger associated with an extended shutdown of flow and either congealing or solidification of the oil. A possible solution which we have studied in the laboratory is the emulsification or dispersion of the oil in water or brine so that shear takes place in the continuous aqueous phase rather than the oil droplets or particles. Synthetic waxy crude oils were prepared by dissolving paraffin wax in white mineral oil at slightly elevated temperatures and then measuring the pour point. One containing 30% wax had a pour point of 43°C and was selected for preparations of the dispersions. This was emulsified in water at a temperature higher than the pour point by using a suitable surfactant as an emulsifying agent. Rheological properties were measured at various temperatures and are reported in the paper. The method shows great promise for use in countries such as China which produce significant quantities of waxy crude oil and have seasonal temperatures significantly lower than the pour point of the crude oil.

Pipeline flow behaviour of heavy crude oil emulsions

AbstractPipeline transportation of heavy oils as oil‐in‐water emulsions has been proposed as an alternative to blending the crude oil with natural gas condensate or other diluent. An 18 m long, 0.02 m I.D. closed loop was constructed to investigate the behaviour of an emulsified Cold Lake crude oil under pipeline flow. Pressure drop was measured as a function of flow rate for freshly produced emulsions to establish correlations of friction factor versus Reynolds number. Stability was observed for long term pipeline flow. The time at which the emulsion breakdown occurred was found to be a function of oil concentration and shear rate. The breakdown of the emulsion was clearly indicated by a simultaneous change in the system variables of pressure drop, temperature and power required to turn the pump at constant speed.