Viscosity Reduction Of Heavy Oil Research Articles

Visual Investigation of Improvement in Extra-Heavy Oil Recovery by Borate-Assisted hbox {CO}_{2}-Foam Injection

The significant reduction in heavy oil viscosity when mixed with hbox {CO}_{2} is well documented. However, for hbox {CO}_{2} injection to be an efficient method for improving heavy oil recovery, other mechanisms are required to improve the mobility ratio between the hbox {CO}_{2} front and the resident heavy oil. In situ generation of hbox {CO}_{2}-foam can improve hbox {CO}_{2} injection performance by (a) increasing the effective viscosity of hbox {CO}_{2} in the reservoir and (b) increasing the contact area between the heavy oil and injected hbox {CO}_{2} and hence improving hbox {CO}_{2} dissolution rate. However, in situ generation of stable hbox {CO}_{2}-foam capable of travelling from the injection well to the production well is hard to achieve. We have previously published the results of a series of foam stability experiments using alkali and in the presence of heavy crude oil (Farzaneh and Sohrabi 2015). The results showed that stability of hbox {CO}_{2}-foam decreased by addition of NaOH, while it increased by addition of hbox {Na}_{2}hbox {CO}_{3}. However, the highest increase in hbox {CO}_{2}-foam stability was achieved by adding borate to the surfactant solution. Borate is a mild alkaline with an excellent pH buffering ability. The previous study was performed in a foam column in the absence of a porous medium. In this paper, we present the results of a new series of experiments carried out in a high-pressure glass micromodel to visually investigate the performance of borate–surfactant hbox {CO}_{2}-foam injection in an extra-heavy crude oil in a transparent porous medium. In the first part of the paper, the pore-scale interactions of hbox {CO}_{2}-foam and extra-heavy oil and the mechanisms of oil displacement and hence oil recovery are presented through image analysis of micromodel images. The results show that very high oil recovery was achieved by co-injection of the borate–surfactant solution with hbox {CO}_{2}, due to in-situ formation of stable foam. Dissolution of hbox {CO}_{2} in heavy oil resulted in significant reduction in its viscosity. hbox {CO}_{2}-foam significantly increased the contact area between the oil and hbox {CO}_{2} significantly and thus the efficiency of the process. The synergy effect between the borate and surfactant resulted in (1) alteration of the wettability of the porous medium towards water wet and (2) significant reduction of the oil–water IFT. As a result, a bank of oil-in-water (O/W) emulsion was formed in the porous medium and moved ahead of the hbox {CO}_{2}-foam front. The in-situ generated O/W emulsion has a much lower viscosity than the original oil and plays a major role in the observed additional oil recovery in the range of performed experiments. Borate also made hbox {CO}_{2}-foam more stable by changing the system to non-spreading oil and reducing coalescence of the foam bubbles. The results of these visual experiments suggest that borate can be a useful additive for improving heavy oil recovery in the range of the performed tests, by increasing hbox {CO}_{2}-foam stability and producing O/W emulsions.

Studies on the interfacial dilational rheology of films containing heavy oil fractions as related to emulsifying properties

In this research, the heavy oil emulsifying and viscosity reducing properties of a series polyethers have been studied by the emulsion stability analysis and viscosity measurements. The experimental results show that the polyethers (with molecular weights of 8400, 12,600 and 14,600) are efficient surfactants for heavy oil emulsification and viscosity reduction. To illustrate the mechanisms, we carried out the study of interfacial properties by interfacial tension and dilational rheology measurements. The experimental results show that the resins and asphaltenes in heavy oil have strong interfacial activity. The adsorption of active components will form interfacial film with certain intensity, which may help to form stable W/O emulsion. On the other hand, the adsorption of polyethers will reduce interfacial tension and form sub-layer construction at higher concentration, which leads to the formation of elastic interfacial layer with a certain strength. For the mixed systems of active components with polyethers, the mixed interfacial layers show almost the same properties just as polyethers used alone, demonstrating that the interfacial layers will be occupied mainly by polyether molecules. The water-soluble polyether with suitable molecular structure will form strong interfacial film, which may be helpful for forming stable O/W emulsion and reducing viscosity of heavy oil obviously.

Visbreaking of Heavy Oil under Supercritical Water Environment

The visbreaking of heavy oil under high-pressure N2 or supercritical water (SCW) environment was experimentally investigated. Despite the difference in the reaction media, the visbreaking follows the same mechanism, that is, dealkylation and condensation of aromatics. The presence of SCW makes it possible that the visbreaking of heavy oil is transferred to the SCW phase with superior diffusivity by which the visbreaking tends to be controlled by intrinsic reaction kinetics rather than by diffusion. Accordingly, dealkylation occurring in the SCW phase, which is vital to the viscosity reduction of heavy oil, responds sensitively to the increase in reaction temperature. Being the secondary reaction of dealkylation at moderate temperatures, condensation is effectively suppressed with reduced reaction time required for dealkylation. By the introduction of SCW and the adoption of an appropriate reaction temperature, the visbreaking efficiency could be drastically improved together with guaranteed stability of v...

Preparation of molybdenum-doped akaganeite nano-rods and their catalytic effect on the viscosity reduction of extra heavy crude oil

Abstract Molybdenum-doped akaganeite nano-rods were prepared by one step facile synthesis. The formation of akaganeite depends on the molar ratio of hexaammonium molybdate to ferric chloride hexahydrate. The nano-rods have an average particle size of ca. 30 nm and disperse uniformly. As a catalyst, the nano-rods can effectively increase the viscosity reduction rate of Shengli Oilfield extra heavy crude oil (175000 mPa s at 50 °C), especially combined with tetralin (a hydrogen donor). The results of SARA analysis, elemental analysis, and 1H NMR spectra indicate that the increase of light component caused by the denitrification and desulfuration of the catalyst plus tetralin as well as the loosening of heavy component molecules can be responsible for the viscosity reduction of the heavy oil.

RETRACTED: Striking behavior of the rheology in heavy crude oils by adding nanoparticles

At the request of the Publisher, the following article has been retracted for redundant publication. Taborda EA, Franco CA, Ruiz AM, Alvarado V, Cortés FB (2017) Striking behavior of the rheology in heavy crude oils by adding nanoparticles. Adsorption Science & Technology. Epub ahead of print 29 August 2017. DOI: 10.1177/0263617417727996 . After publication, the Adsorption Science & Technology Editorial Office became aware that this article had been simultaneously submitted to Adsorption Science & Technology, and two other journals: Chemical Engineering Communications and Energy Fuels, which resulted in the redundant publication of the above article. The above article is near-identical to the following articles published by the same group of authors in Chemical Engineering Communications and Energy & Fuels. Taborda EA, Franco CA, Ruiz AM, Alvarado V, Cortés FB (2017) Anomalous Heavy-Oil Rheological Thinning Behavior upon Addition of Nanoparticles: Departure from Einstein’s Theory. Chemical Engineering Communications 204(6): 648–657. Taborda EA, Franco CA, Ruiz AM, Alvarado V, Cortés FB (2017) Experimental and Theoretical Study of Viscosity Reduction in Heavy Crude Oils by Addition of Nanoparticles. Energy Fuels 31(2): 1329–1338.

Enhanced viscosity reduction in heavy oils by subcritical water

We determine the chemical changes associated with viscosity reduction when heavy oil is cracked in subcritical water. The viscosity reduction has a temperature threshold for onset of 290 °C—this suggests an enhanced acid cracking regime associated with the maximisation of water dissociation at these conditions aided by the already increased solubility. The mean molecular weight is reduced by nearly 50%. Oxygen and sulphur are reduced by about half of this—either by expelled gas effluent ({text{H}}_{2} {text{S}}) or by conversion into mono-aromatic base sulphur-containing structures. The amount of lower branched paraffins is increased.

Kinetic studies on extra heavy crude oil upgrading using nanocatalysts by applying CFD techniques

Abstract Regarding the growth of global energy consumption and the paucity of light crude oil, extracting and using heavy and extra heavy crude oil has received much more attention, but the application of this kind of oil is complicated due to its very high molecular weight. High viscosity and low flowability complicate the transportation of heavy and extra heavy crude oil. Accordingly, it is essential to reduce the viscosity of heavy and extra heavy crude oil through in-situ operations or immediate actions after extraction to reduce costs. Numerical simulations are influential methods, because they reduce calculation time and costs. In this study, the cracking of extra heavy crude oil using computational fluid dynamics is simulated, and a unique kinetic model is proposed based on experimental procedures to predict the behavior of extra heavy crude oil cracking reaction. Moreover, the hydrodynamics and heat transfer of the system and influence of nanocatalysts and temperature on the upgrading of crude oil are studied. The geometry of a reactor is produced using commercial software, and some experiments are performed to examine the validity and accuracy of the numerical results. The findings reveal that there is a good agreement between the numerical and experimental results. Furthermore, to investigate the main factors affecting the process, sensitivity analysis is adopted. Results show that type of catalyst and concentration of catalyst are the parameters that influence the viscosity reduction of extra heavy crude oil the most. The findings further revealed that when using a 25 nm SiO2 nanocatalyst, a maximum viscosity reduction of 98.67% is observed at 623 K. Also, a catalyst concentration of 2.28wt% is best for upgrading extra heavy crude oil. The results obtained through sensitivity analysis, simulation model, and experiments represent effectual information for the design and development of high performance upgrading processes for energy applications.

Rheological behavior and viscosity reduction of heavy crude oil and its blends from the Sui-zhong oilfield in China

This paper presents an experimental study on the rheological behavior and viscosity reduction of heavy crude oil and its blends to improve the pipeline transportation by using a Haake RS6000 rheometer and a lab scale flow loop. The apparent viscosity, thixotropic behavior, yield stress and viscoelastic properties were investigated. The results of rheological measurements indicated that with the increase in the diesel volumetric concentration, the viscous modulus and thixotropic behavior of the mixture decreased remarkably; on the contrary, the elastic modulus of heavy crude oil was found to increase slightly. When the start-up rates during the pipe flow were constant, the yield stress decreased exponentially with the increase in temperature. A comparison between rheological measurements and pipe flow data showed that the yield stress measured by the rheometer could be used to predict the start-up yield stress during pipe flow through linear interpolation.In pipeline flow, the pressure drop was reduced greatly by both heating and dilution with lighter crudes because the viscosity of the heavy crude oil decreased significantly. Drag reduction due to gas injection only occurred at low temperatures or large superficial oil velocities. Moreover, a new viscosity model of heavy crude oil was developed based on the viscosity at 50 °C to predict the viscosity of heavy crude oil from several oil fields in China. The results reveal that the developed model provided good predictions. Considering that the data contained a wide range of viscosity values, the model suggested in this work is acceptable for practical applications in industry.

Double alkyl chain copolymers as flow improvers for heavy oil

ABSTRACTAs flow improvers for heavy crude oil, two oil-soluble copolymers (DM-S-VA, DA-S-VA) were successfully synthesized and characterized by 1H NMR and GPC. A rich alkyl chain and appropriate molecular weight of copolymer play fundamental role in viscosity reduction of heavy oil. Furthermore, synergistic effect of surfactants on polymers can promote the viscosity reduction, and the best formulation can increase the viscosity reduction rate to 78% to oil A. Comparing with the apparent viscosity of the different heavy oil mixing system in a wide shear rate range (0.1–200 s−1), the results show good stability and viscosity reducing effect.

Viscosity reduction of extra heavy crude oil by magnetite nanoparticle-based ferrofluids

The main objective of this work is to synthesize and evaluate magnetite (Fe3O4) nanoparticle-based ferrofluids for reducing the viscosity of an extra heavy crude oil. The carrier fluid of the nanoparticles was synthesized using an engine lubricant recycled from the automotive industry and hexadecyltrimethylammonium bromide as a surfactant. Fe3O4 nanoparticles were synthesized by coprecipitation method. The effect of the concentration of nanoparticles in the viscosity reduction degree was determined for dosages between 0 and 50,000 mg/L. Different dosages of carrier fluid were evaluated between 0 and 10% v/v. The effects of the amount of brine emulsified, temperature, time, and shear rate were assessed. Overall, the results showed that viscosity and shear stress of extra heavy crude oil could be reduced up to 81 and 78% in the presence of ferrofluid, respectively. The rheological behavior of extra heavy crude oil in the presence and absence of ferrofluid was assessed by Cross, Ostwald-de Waele, and Herschel-Bulkley models.

Anomalous Heavy-Oil Rheological Thinning Behavior upon Addition of Nanoparticles: Departure from Einstein’s Theory

Heavy and extra-heavy oils generally exhibit high viscosity, which is detrimental to their production, transport, and refining. The oil & gas industry has thoroughly investigated the use of chemical agents to improve the mobility of these types of low-quality crude oils at the surface as well as under reservoir conditions for many years. In this sense, the main objective of this paper is to provide unexpected experimental evidence of heavy oil and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles (NPs) of different chemical natures (SiO2, Fe3O4, and Al2O3), particle size, surface acidity, and concentration at low-volume fractions. The viscosity of the enhanced fluids was measured using a rotational rheometer at shear rates varying between 1 and 75 s−1. Upon addition of NPs, viscosity reduction was observed in all cases evaluated. The maximum viscosity reduction of roughly 52% was obtained at a concentration of 1000 mg/L with 7 nm SiO2 NPs at low shear rate, below 10 s−1, contrary to expectations from Einstein’s viscosity theory in particulate systems. A mathematical model based on a modification to the Pal and Rhodes Model for the viscosity of suspensions is proposed in this work. The said model was validated successfully using experimental data, as evidenced by RSME% values lower than 10%. The importance of our findings lies in the lack of previous experimental and theoretical data in the open literature showing heavy crude oils viscosity reduction in the presence of NPs.

Emergence of nanotechnology in the oil and gas industry: Emphasis on the application of silica nanoparticles

Abstract The application of nanotechnology in the oil and gas industry is on the rise as evidenced by the number of researches undertaken in the past few years. The quest to develop more game-changing technologies that can address the challenges currently facing the industry has spurred this growth. Several nanoparticles, of different sizes and at different concentrations, have been used in many investigations. In this work, the scope of the study covered the application of nanotechnology in drilling and hydraulic fracturing fluids, oilwell cementing, enhanced oil recovery (which includes transport study, and foam and emulsion stability), corrosion inhibition, logging operations, formation fines control during production, heavy oil viscosity reduction, hydrocarbon detection, methane release from gas hydrates, and drag reduction in porous media. The observed challenges associated with the use of nanoparticles are their stability in a liquid medium and transportability in reservoir rocks. The addition of viscosifier was implemented by researchers to ensure stability, and also, surface-treated nanoparticles have been used to facilitate stability and transportability. For the purpose of achieving better performance or new application, studies on synergistic effects are suggested for investigation in future nanotechnology research. The resulting technology from the synergistic studies may reinforce the current and future nanotechnology applications in the oil and gas industry, especially for high pressure and high temperature (HPHT) applications. To date, majority of the oil and gas industry nanotechnology publications are reports of laboratory experimental work; therefore, more field trials are recommended for further advancement of nanotechnology in this industry. Usually, nanoparticles are expensive; so, it will be cost beneficial to use the lowest nanoparticles concentration possible while still achieving an acceptable level of a desired performance. Hence, optimization studies are also recommended for examination in future nanotechnology research.

Application and mechanism of ultrasonic static mixer in heavy oil viscosity reduction

In the present study, heavy oil viscosity reduction in Daqing oil field was investigated by using an ultrasonic static mixer. The influence of the ultrasonic power on the viscosity reduction rate was investigated and the optimal technological conditions were determined for the ultrasonic treatment. The mechanism for ultrasonic viscosity reduction was analyzed. The flow characteristics of heavy oil in the mixer under the effect of cavitation were investigated using numerical modeling, and energy consumptions were calculated during the ultrasonic treatment and vis-breaking processes. The experimental results indicated that the ultrasonic power made the largest impact on the viscosity reduction rate, followed by the reaction time and temperature. The highest viscosity reduction rate was 57.34%. Vacuole was migrated from the axis to the wall along the fluid, accelerating the two-phase transmission and enhancing the radial flow of the fluid, which significantly improved the ultrasonic viscosity reduction. Compared to the vis-breaking process, the energy consumption of ultrasonic treatment process was 43.03% lower when dealing with the same quality heavy oil. The optimal process conditions were found to be as follows: ultrasonic power of 1.8kW, reaction time of 45min and reaction temperature of 360°C. The dissociation of the molecules of heavy oil after ultrasonication has been checked. After being kept at room temperature 12days, some light components were produced by the cavitation cracking, so the viscosity of the residual oil could not return to that of the original residual oil, which meant that the “cage effect” was not reformed.

Experimental and Theoretical Study of Viscosity Reduction in Heavy Crude Oils by Addition of Nanoparticles

Heavy and extra-heavy oils generally exhibit high viscosity, which is detrimental to their production, transport, and refining. The oil and gas industry has thoroughly investigated the use of chemical agents to improve the mobility of this type of low-quality crude oil at the surface as well as reservoir conditions for many years. In this sense, the main objective of this paper is to provide unexpected experimental evidence of heavy oil and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles (NPs) of different chemical natures (SiO2, Fe3O4, and Al2O3), particle size, surface acidity, and concentration at low-volume fractions. The viscosity of the enhanced fluids was measured using a rotational rheometer at shear rates varying between 1 and 75 s–1. Upon addition of nanoparticles, viscosity reduction was observed in all cases evaluated. However, the maximum viscosity reduction of roughly 52% was obtained at a concentration of 1000 mg/L with 7 nm SiO2 nanoparticles at shea...

Effect of reaction temperature and hydrogen donor on the Ni0@graphene-catalyzed viscosity reduction of extra heavy crude oil

ABSTRACTNi0@graphene nanocomposites were prepared via a solvothermal method and used as the catalysts for the viscosity reduction of extra heavy crude oil. Higher graphene content in Ni0@graphene nanocomposite has an adverse effect on its catalytic activity. The addition of tetralin and higher reaction temperature can obviously promote the catalytic activity. The catalyst accompanied by hydrogen donor can attain a viscosity reduction rate of 84.3% after the catalytic reaction under 280°C for 24 h and reduce the viscosity of crude oil from 174,219 to 27,352 mPa s (measured at 50°C).

Clean aquathermolysis of heavy oil catalyzed by Fe(III) complex at relatively low temperature

ABSTRACTIn order to develop a clean catalyst for aquathermolysis of heavy oil at relatively low temperature, a series of water-soluble Fe(III) complexes were prepared as the catalysts for the catalytic aquathermolysis of heavy oil. Under the optimized condition, the adding amount of Fe-3 (a complex of Fe(III) and citrate) is 0.1%, the reaction temperature is 180°C, and the reaction time is 24 h, the heavy oil viscosity reduction ratio reaches to 80.1% (40°C). Results of the composition analysis show that the contents of resin and asphaltene decrease and the saturated hydrocarbon and aromatic increase. GC analysis shows that the light components increase remarkably after the aquathermolysis.

Experimental study and numerical simulation of a solvent-assisted start-up for SAGD wells in heavy oil reservoirs

Effective communication in the well pair during the preheating period has a significant effect on the success of the production period by using steam-assisted gravity drainage (SAGD) technology in heavy oil reservoirs. However, the time-consumption and the economic cost associated with steam generation and circulation limit the application of this technique. Because of these limitations and concerns, we have investigated the effectiveness of the solvent injection-assisted start-up period. A sand-pack physical experiment was designed to evaluate the effect of solvent on heavy oil-viscosity reduction. Different solvents were tested to examine the effects on viscosity reduction and asphaltene precipitation. Xylene was selected as asphaltene-soluble solvent for this experiment. The solvent was injected at different injection rates and diffused into the bitumen during the soaking period. Furthermore, a numerical model was constructed to simulate the performance of the preheating and early production period with or without solvent injection in the start-up process. The observations and simulation results indicate that the injected solvent diffuses to improve the sweep area to further reduce oil viscosity significantly in the soaking time. However, too long soaking time results in lower concentrations of solvent has the opposite effect on oil-viscosity reduction. The relative permeability of the oil phase increases as well. Whereas, according to numerical simulation, the solvent-assisted start-up process of SAGD shortens preheating time and reduces steam consumption. Both the production rate and the cumulative oil production improve during the early production period.

Combined Cyclic Solvent Injection and Waterflooding in the Post-Cold Heavy Oil Production with Sand Reservoirs

In this paper, cyclic solvent injection (CSI) and waterflooding (WF) were combined and studied to maximize their technical synergy and optimize the enhanced heavy oil recovery (EHOR) in the post-cold heavy oil production with sand (CHOPS) reservoirs. The original heavy oil sample was collected from the Colony formation in western Canada. The PVT data and viscosities of CH4/CO2/C3H8-saturated heavy oil were measured at different equilibrium pressures and Tres = 21 °C. A total of eight sandpacked laboratory tests were conducted to study and compare four different EHOR processes after the primary production: CSI, CSI + WF, simultaneous CSI + WF, and WF + CSI. In the last three processes, WF was applied after, simultaneously with, and prior to the CSI production, respectively. Three different pressure drawdown rates (6.8, 12.5, and 25.0 kPa/min) and two different solvents (CO2 and C3H8) were used to determine their specific effects on CSI + WF. The experimental results showed that CSI + WF had the highest heavy oil recovery factor (RF) of 30.1% in comparison with 28.9, 25.9, and 24.3% for WF + CSI, simultaneous CSI + WF, and CSI, respectively, when CO2 was used in CSI. The intermediate pressure drawdown rate of 12.5 kPa/min resulted in the highest heavy oil RF in CO2-CSI + WF. In addition, C3H8 was found to be a more effective extracting solvent than CO2 due to its more favorable PVT properties and larger heavy oil viscosity reduction.

Enhancing heavy-oil recovery by using middle carbon alcohol-enhanced hot polymer flooding

In this paper, the effects of middle carbon alcohol-enhanced hot polymer flooding for improving heavy-oil recovery were investigated by using several sandpack flooding tests. Before that, the effect of different middle carbon alcohols on viscosity reduction of heavy oil were examined. Then, a new method was developed to examine the diffusion of middle carbon alcohols from water to heavy oil and its effect on viscosity reduction of heavy oil. The results show that the effect of middle carbon alcohols on reducing heavy-oil viscosity increases with their carbon number; Besides, the middle carbon alcohols can diffuse from water to heavy oil to significantly reduce its viscosity, and the viscosity reduction effect increases with temperature, strring time in a certain range. Sandpack flooding tests show that injection of hot polymer and addition of middle carbon alcohols can both effectively enhance heavy-oil recovery; The effect of middle carbon alcohol-polymer flooding increases with the temperature of polymer solution and the injection rate of polymer solution.

Experimental study of Iranian heavy crude oil viscosity reduction by diluting with heptane, methanol, toluene, gas condensate and naphtha

Abstract Due to the high viscosity of heavy crude oils, production from these reservoirs is a demanding task. To tackle this problem, reducing oil viscosity is a promising approach. There are various methods to reduce viscosity of heavy oil: heating, diluting, emulsification, and core annular flow. In this study, dilution approach was employed, using industrial solvents and gas condensate. The viscosity of two Iranian heavy crude oils was measured by mixing with solvents at different temperatures. Dilution of both oil samples with toluene and heptane, resulted in viscosity reduction. However, their effect became less significant at higher concentrations of diluent. Because of forming hydrogen bonds, adding methanol to heavy crude oil resulted in higher viscosity. By adding condensate, viscosity of each sample reduced. Gas condensate had a greater impact on heavier oil; however, at higher temperatures its effect was reduced. Diluting with naphtha decreased heavy oil viscosity in the same way as n-heptane and toluene. Besides experimental investigation, different viscosity models were evaluated for prediction of heavy oil/solvent viscosity. It was recognized that Lederer' model is the best one.