Low-viscosity Oil Research Articles

New Functionality of Ionic Liquids as Lubricant Additives: Mitigating Rolling Contact Fatigue.

Oil-soluble ionic liquids (ILs) have recently been demonstrated as effective lubricant additives of friction reduction and wear protection for sliding contacts. However, their functionality in mitigating rolling contact fatigue (RCF) is little known. Because of the distinct surface damage modes, different types of surface protective additives often are used in lubricants for sliding and rolling contacts. Therefore, the lubricating characteristics and mechanisms of ILs learned in sliding contacts from the earlier work may not be translatable to rolling contacts. This study explores the feasibility of using phosphonium-phosphate, ammonium-phosphate, and phosphonium-carboxylate ILs as candidate additives in rolling-sliding boundary lubrication, and results suggested that an IL could be either beneficial or detrimental on RCF depending on its chemistry. Particularly, the best-performing phosphonium-phosphate IL at 2% addition made a low-viscosity base oil significantly outperform a more viscous commercial gear oil in reducing the RCF surface damage and associated vibration noise. This IL generated a thicker, smoother, and more homogeneous tribofilm compared with commercial additives, which is likely responsible for the superior RCF protection. Results here suggest good potential for using appropriate IL additives to allow the use of low-viscosity gear and axle fluids for improved efficiency and durability.

The Study of Waterflood Stimulation Technology

Aiming at the development status of Liuxi Oilfield, waterflood stimulation is studied to improve the development effect. The process is as follows: in begin with, the displacement liquid is injected into the oil well quickly to replenish energy; then the oil well is closed a while to promote oil and water displacement; finally, let the oil well produce under a reasonable system of production. Strong water-wet, high oil saturation, the degree of fracture development and low oil viscosity are the advantages of using waterflood stimulation by analyzing related researches. Based on the reservoir engineering research, numerical simulation method which is about waterflood stimulation is established using Eclipse software. According to the numerical simulation results, assuming that injection rounds is one time, when injection volume is more, the formation pressure rises higher and the liquid sweep is wider and cumulative production is more. At the same time, the degree of stage production is increasing with the closed time lengthen. But it has the most optimum values about the closed time, and the production increase of the degree of stage production becomes significantly slow.

The associative polymer flooding: an experimental study

This study investigates the sandpack displacement of low viscosity oil (1.68 cP) by brine and aqueous solutions of associative polymers. Polymer flooding has been thoroughly investigated in many laboratory and field tests. Polymer flooding is one of the most widely used enhanced oil recovery (EOR) methods. The method of polymer flooding is not used for development of oil fields with gas caps, fractured reservoirs, high permeability and active bottom-water drive. In the application of polymer flooding, coefficient of oil recovery is increased by 3–10%. Hydrolyzed polymers undergo the significant thermal and chemical degradation at high temperature and salinity. In recent years, researchers have turned their attention to associative polymers. An application of associative polymers to withstand degradation in high temperature and high salinity conditions can enhance oil recovery in high heterogeneous fields. This article presents the results of studies of oil displacement by associative polymers in a two-layer core model. In laboratory studies, the core selected from a sandy reservoir of the South Turgay Basin of the Republic of Kazakhstan was used. Solutions of the following polymers were studied: hydrolyzed polyacrylamide (HPAM) and associative polymer. The physicochemical conditions of the experiments corresponded to the reservoir conditions of the sand layer of the South Turgay Basin: temperature of 82 °C and the salinity of the brine 92,000 ppm. Experiments revealed that the associative polymer is more stable in simulated reservoir conditions than the HPAM polymer. Associative polymer flooding was recommended for pilot testing at the reservoir of the South Turgay Basin.

Laboratory study of oil saturation and oil/water substitution effects on a sandstone’s modulus dispersion and attenuation

Using the stress–strain oscillation method, we conducted experiments on a sandstone over a frequency range of 1–100 Hz at a differential pressure of 5 MPa to investigate the effects of oil saturation and oil/water substitution on modulus dispersion and attenuation. We first saturated the sandstone with a low viscosity oil (2#) at different saturation degrees, then replaced the 2# oil with a more viscous oil (68#) and finally injected distilled water in the oil-saturated sample. Young’s modulus, Poisson’s ratio and extensional attenuation were measured during these saturation processes. The measured moduli of this sandstone, when saturated with the 2# oil at different saturation degrees (0% to 100%) or when fully saturated with the 68# oil, manifest little dispersion over the frequency range of 1–100 Hz, and low attenuation was observed. The measured bulk modulus for the oil-saturated sandstone agrees well with the prediction of Gassmann’s fluid-substitution theory, suggesting that wave-induced fluid flow (WIFF) plays an insignificant role in control of the bulk modulus when the sandstone is filled with oil. However, as oil saturation and viscosity increase, the shear modulus keeps increasing, violating the Gassmann’s fluid-substitution theory, which may be caused by the viscous coupling mechanism. When water was injected into sandstone fully saturated with the 68# oil, distinct modulus dispersion and attenuation were observed. The characteristics of the modulus dispersion and attenuation are consistent with mesoscopic WIFF theory, indicating that mesoscopic WIFF is the main cause of modulus dispersion and attenuation for this sandstone saturated with oil–water mixture at seismic frequencies.

INTENSIFICATION OF THE STABLE WATER-OIL EMULSIONS BREAKING PROCESS USING NEW EFFECTIVE COMPOSITE DEMULSIFIERS

One of the directions for improving the efficiency of the processes of oil extraction, transport and preparation, complicated by the emulsions formation, is the effective demulsifiers creation available by developing synergistic compositions based on nonionic surfactants, which, along with the properties inherent in individual components, have a properties complex that are the their joint action resul. The compositions use is more effective than the any substance use in its pure form. Given this, it should be noted that the development of new composite demulsifiers based on available surfactants is an important task. Studies have been carried out to obtain the ammonium salts of oleic acid, to determine their physicochemical properties and capability of using them as an additive to the initial demulsifier to increase the demulsifying ability. It is found that the compositions consisting of the original demul- sifier, which contains 47 wt. % Nonionic surfactants and 53 wt. % sol- vent, in addition containing 5 wt. % amine complex salts of oleic acid, exhibit high demulsifying activity and enable deep dehydration of both low-viscosity and high-viscosity oils.

RAFT Dispersion Polymerization in Silicone Oil

A near-monodisperse monohydroxy-terminated polydimethylsiloxane (PDMS; mean degree of polymerization = 66) was esterified using a carboxylic acid-functionalized trithiocarbonate to yield a PDMS 66 precursor with a mean degree of functionality of 92 ± 5% as determined by 1 H NMR spectroscopy. This PDMS 66 precursor was then chain-extended in turn using eight different methacrylic monomers in a low-viscosity silicone oil (decamethylcyclopentasiloxane, D5). Depending on the monomer type, such syntheses proceeded via either RAFT dispersion polymerization or RAFT emulsion polymerization. In each case the target DP of the core-forming block was fixed at 200, and the copolymer concentration was 25% w/w. Transmission electron microscopy studies indicated that kinetically trapped spheres were obtained in almost all cases. The only exception was 2-(dimethylamino)ethyl methacrylate (DMA), which enabled access to spheres, worms, or vesicles. This striking difference is attributed to the relatively low glass transition temperature for this latter block. A phase diagram was constructed for a series of PDMS 66 -PDMA x nano-objects by systematically increasing the PDMA target DP from 20 to 220 and varying the copolymer concentration between 10 and 30% w/w. Higher copolymer concentrations were required to access a pure worm phase, while only spheres, vesicles, or mixed phases were accessible at lower copolymer concentrations. Gel permeation chromatography studies indicated a linear evolution of number-average molecular weight (M n ) with PDMA DP while dispersities remained below 1.40, suggesting relatively well-controlled RAFT polymerizations. Small-angle X-ray scattering (SAXS) was used to characterize selected examples of spheres, worms, and vesicles. PDMS 66 -PDMA 100-112 worms synthesized at 25-30% w/w formed free-standing gels at 20 °C. Oscillatory rheology studies performed on a 30% w/w PDMS 66 -PDMA 105 worm dispersion indicated a storage modulus (gel strength) of 1057 Pa and a critical gelation concentration (CGC) of approximately 12% w/w. Finally, PDMS 66 -PDMA x worms could also be prepared in n-dodecane, hexamethyldisiloxane, or octamethylcyclotetrasiloxane. Rotational rheometry studies indicate that such worms are efficient viscosity modifiers for these nonpolar oils.

Experimental studies of the working processes of a reciprocating hybrid power machine with a slot seal of step-type with various working fluids

The article considers results of experimental studies of a piston hybrid power machine with a slot seal of step-type. While experimental studies, the following parameters were taken as independent parameters: the type of cooling liquid (I-20A oil and MGE-46B oil were used), the injection pressure in the compressor section, the discharge pressure in the pump section, the crankshaft speed.The experimental studies determined that using of low-viscosity oil I-20A made possible to reduce the temperature of the cylinder-piston group and the temperature of the intake gas.

Modes of coalescence of aqueous anchored drops in insulating oils under an electric field

The electrocoalescence of aqueous drops in an insulating oil is the fundamental process in the dehydration of emulsions of water in insulating oils, such as crude oils. The great difference in the conductivity of the aqueous droplets and the oil used as the suspending medium suggests that the conductivity of the oil medium should not affect the coalescence process. In this work, contrary to this expectation, we show a very strong dependence of the conductivity of the insulating oil on the mode of droplet coalescence. Experiments are reported using silicone oils, vegetable oils, and hydrocarbons, in the anchored drop setup that also facilitates the use of low viscosity oils. Our study indicates that the droplet undergoes cone-cone mode of interaction at low conductivities of the oil medium. On the other hand, when the conductivity of the oil is increased, the cone-dimple mode of coalescence is observed when the viscosity of the oil phase is higher, while a cone-spray-dimple mode is observed when oils of low viscosity are used.

Research and existing problems of pour point depressant/viscosity reducer for crude oil production

The composition and structure of pour point depressant/viscosity reducer for pipeline transportation and its application effect in long-distance pipeline transportation in China as well as the application effect of oil-soluble viscosity reducer and water-soluble viscosity reducer for wellbore lift in low-viscosity and high-viscosity heavy oil wells in China are introduced. The main technical problems existing in the study of viscosity reducer for heavy oil formations drive are presented.

Femtosecond laser surface texturing of diamond-like nanocomposite films to improve tribological properties in lubricated sliding

We report on femtosecond laser ablation and surface micropatterning (texturing) of diamond-like nanocomposite (DLN) films (a-C:H:Si:O films), aimed to improve tribological properties of laser-patterned films under lubricated sliding conditions. Femtosecond laser system generating pulses of 320-fs duration at the wavelength 515 nm is applied. Femtosecond laser ablation of 2.7-μm-thick DLN films is studied to determine optimum irradiation parameters for laser surface texturing with the requirements of the minimal spot size, high ablation rate, surface quality and pattern depth less than the film thickness. Periodic microcrater patterns (with 10 μm diameter, 2.2 μm depth, and different area density of microcraters) have been fabricated on the DLN films over the areas of 6 mm × 10 mm size. Tribological tests of the original and laser-patterned DLN films are performed using a ball-on-flat tribometer under linear reciprocating sliding against 100Cr6 steel balls in the presence of oil lubrication (engine oils of low and high viscosity). The ball-on-flat investigations have demonstrated the reduced friction and wear properties of the laser-textured DLN films, depending on the area density of microcraters and lubrication conditions. The obtained results evidence that femtosecond laser surface texturing is an effective technique to improve lubricated sliding performance of the DLN coatings.

Self-Healing Microcapsule-Thickened Oil Barrier Coatings

Low-viscosity oils could potentially act as self-healing barrier coatings because they can readily flow and reconnect to heal minor damage. For the same reason, however, they typically do not form stable coatings on metal surfaces. Increasing viscosity helps to stabilize the oil coating, but it also slows down the healing process. Here, we report a strategy for creating highly stable oil coatings on metal surfaces without sacrificing their remarkable self-healing properties. Low-viscosity oil films can be immobilized on metal surfaces using lightweight microcapsules as thickeners, which form a dynamic network to prevent the creep of the coating. When the coating is scratched, oil around the opening can rapidly flow to cover the exposed area, reconnecting the particle network. Use of these coatings as anticorrosion barriers is demonstrated. The coatings can be easily applied on metal surfaces, including those with complex geometries, both in air or under water, and remain stable even in turbulent water. They can protect metal in corrosive environments for extended periods of time and can self-heal repeatedly when scratched at the same spot. Such a strategy may offer effective mitigation of the dangerous localized corrosion aggravated by minor imperfections or damage in protective coatings, which are typically hard to prevent or detect, but can drastically degrade metal properties.

Study on cavitation phenomenon of twin-tube hydraulic shock absorber based on CFD

To prevent the occurrence of the cavitation phenomenon in hydraulic shock absorber, the production process of the cavitation during the recovery process of shock absorber is studied, and the parameter model of cavitation production mechanism is built. Based on Computational Fluid Dynamics (CFD) numerical method, a high-precision mesh model of shock absorber is established and the simulation analysis is carried out by using FLUENT software. Therefore, the specific position and distribution of cavitation in the hydraulic shock absorber are obtained, and the measures to inhibit cavitation are put forward. Finally, the simulation results are verified by experimental study and the experimental results show that the cavitation is mainly distributed around the recovery valve of shock absorber, and the cavitation phenomenon becomes more obvious with increasing the piston speed; using low viscosity oil and increasing the diameter of piston rod can effectively inhibit cavitation phenomenon. This study provides a certain reference for preventing the cavitation phenomenon of hydraulic shock absorber.

Self-Healing Microcapsule-Thickened Oil Barrier Coatings.

Low-viscosity oils could potentially act as self-healing barrier coatings because they can readily flow and reconnect to heal minor damage. For the same reason, however, they typically do not form stable coatings on metal surfaces. Increasing viscosity helps to stabilize the oil coating, but it also slows down the healing process. Here, we report a strategy for creating highly stable oil coatings on metal surfaces without sacrificing their remarkable self-healing properties. Low-viscosity oil films can be immobilized on metal surfaces using lightweight microcapsules as thickeners, which form a dynamic network to prevent the creep of the coating. When the coating is scratched, oil around the opening can rapidly flow to cover the exposed area, reconnecting the particle network. Use of these coatings as anticorrosion barriers is demonstrated. The coatings can be easily applied on metal surfaces, including those with complex geometries, both in air or under water, and remain stable even in turbulent water. They can protect metal in corrosive environments for extended periods of time and can self-heal repeatedly when scratched at the same spot. Such a strategy may offer effective mitigation of the dangerous localized corrosion aggravated by minor imperfections or damage in protective coatings, which are typically hard to prevent or detect, but can drastically degrade metal properties.

Application of waste polypropylene bags as filter media in coalescers for oily water treatment

The polypropylene fibers have been used in bed coalescers for separation of micro-sized oil droplets from water for a long time. Possibilities of applying different forms of polypropylene as filter beds are still being in the focus of many researches. The possibility of applying waste polypropylene bags used for packing vegetables (PPDJ) was investigated in this paper. The results are compared with results obtained by applying waste polypropylene fibers from carpet production (PP). It is well known that there are difficulties to separate the oils of low viscosity by polymer fiber beds. Due to the above mentioned, the presented research refers to separation of low viscosity mineral oil from water. The obtained experimental results confirm that the material PPDJ could be efficiently used as a bed material for coalescers. The critical velocity of 50 m h-1 could be reached at using both polypropylene forms that is from bags PPDJ and from the carpet industry PP, when the adequate bulk density of materials is used.

Combined lubricant–surface system approach for potential passenger car CO2 reduction on piston-ring-cylinder bore assembly

The impact of reducing friction losses on the fuel consumption and CO2 emissions was investigated through computational simulation of piston ring dynamics. Experimentally determined cylinder bore surface finishes, low viscosity oil and ring coatings response to oil additives were used as simulation inputs. Oil viscosity grades from SAE10W-40 to SAE0W-4 were considered. 3D roughness measurements of regular and “mirror-like” cylinder bores were used to estimate the flow factors coefficients for the average Reynolds equation and asperity contact stiffness. The combination of smooth cylinder bores, low viscosity oils with appropriate additives promoted ring pack FMEP reductions of up to 66% at part load and WOT with consequent CO2 reductions of up to 10% at part load and 1.5% at WOT.

Effect of vug filling on oil-displacement efficiency in carbonate fractured-vuggy reservoir by natural bottom-water drive: A conceptual model experiment

Universal existence of the filled vug or cave in carbonate reservoir complicates the fluid flow as the coexistence of free flow and porous flow. The fills in vug increase the flow resistance and affect the water invasion for a natural bottom-water reservoir. This influence was explored through experimental tests on a conceptual discrete fractured-vuggy model. This model was abstracted from Tahe Oilfield in China, in the form of isolated vugs connected by fractures network. A new scaling method was proposed for this discrete media according to the similarity of the displacement front of water drive. It was found that vug filling displays a negative role during the natural bottom-water drive. This impact depends on the geological feature of fractured-vuggy reservoir. A stronger sensitivity occurred to the fracture well-developed stratum that the vug filling made the pre-existing or new preferential corridors more significant. As a result, the systems with multiple flow paths became more “heterogeneous”. In this condition, a lower water intensity and oil viscosity can ease these adverse effects.

Influence of Lubricant Pressure Response on Subsurface Stress in Elastohydrodynamically Lubricated Finite Line Contacts

In order to adapt to increasingly stringent CO2 regulations, the automotive industry must develop and evaluate low cost, low emission solutions in the powertrain technology. This often implies increased power density and the use of low viscosity oils, leading to additional challenges related to the durability of various machine elements. Therefore, an increased understanding of lubricated contacts becomes important where oil viscosity–pressure and compressibility–pressure behavior have been shown to influence the film thickness and pressure distribution in elastohydrodynamic lubrication (EHL) contacts, further influencing the durability. In this work, a finite line EHL contact is analyzed with focus on the oil compressibility–pressure and viscosity–pressure response, comparing two oils with relatively different behavior and its influence on subsurface stress concentrations in the contacting bodies. Results indicate that increased pressure gradients and pressure spikes, and therefore increased localized stress concentrations, can be expected for stiffer, less compressible oils, which under transient loading conditions not only affect the outlet but also the edges of the roller.

Vacuum Tribological Performance of WS2–MoS2 Composite Film Against Oil-Impregnated Porous Polyimide: Influence of Oil Viscosity

To achieve the desired levels of performance and durability for bearings applied in space, a novel solid–liquid dual lubricating system was established via the WS2–MoS2 composite films sliding against oil-impregnated porous polyimide (PPI), in which polyalphaolefin (PAO) oils with different viscosities were used, respectively. The contact angle measurement indicated that the PAO oil had good wettability on the surfaces of the composite film and the PPI. The vacuum tribological behaviors of single WS2–MoS2 composite film and the dual lubricating system were mainly evaluated under different loads and speeds. In comparison with single WS2–MoS2 composite film, the dual lubricating system exhibited the low friction coefficient and synergistic lubricating effect for the low-viscosity PAO oil under severe sliding conditions. It was concluded that the cleavages of the WS2 and MoS2 crystals along the basal plane were more sufficient and formed small and thin WS2 and MoS2 platelets in the dual lubricating system. Meanwhile, it was found that oil-impregnated PPI readily released PAO lubricating oil with low viscosity, which further decreased friction on the contact interface. The lubricating mechanism of the dual lubricating system was also revealed after correlating the tribological behaviors of the different lubricating systems.

Oil removal from water surface using reusable and absorptive foams via simple fabrication of liquid natural rubber (LNR)

A novel macroporous and oleophilic Natural Rubber (NR) foam is prepared through a vulcanization process using methanol (CH3OH) as solvent at different compositions of crosslinking agent (Disulphur Dichloride, S2Cl2). NR was firstly modified to reduce its molecular weight by photochemical oxidation method to produce Liquid Natural Rubber (LNR). This spongy-like foam made of LNR was firstly reported here, has produced interconnected open-cell structures with pore volume ranged from 1.83 mL/g to 4.28 mL/g and diameter sizes between 2.09 μm and 13.24 μm. The absorption capability of LNR-foam resembled to the cotton fiber-based sorbent where it absorbed most of oil products by up to 9.39 g/g. The porous materials reached the saturation limit within 5 min of low-viscosity oils, and 15 min for higher-viscosity oils. In a simulated oil slick system, this LNR macroporous and hydrophobic foams maintained its high oil absorption capacity in the ranged of 3.54 g/g to 9.39 g/g. About 90% of absorbed oil is being recovered and the LNR-foams are able to perform up to 20 absorption cycles which demonstrated a good reusability. Hence, this new type of natural-based modified absorbent has the potentials to be commercialized.

Composition and Property Changes in Oil Dispersions After Hydrothermal Treatment of Rock-Forming Minerals with Hydrocarbon Solvents

Group and elemental compositions and structures of hydrocarbon dispersions in super-viscous oil resulting from steam and heat exposure at 140-190°C and 3-6 atm in the presence of hexane and benzene are established using simplified models of terrigenous and carbonate reservoirs. A relationship between the composition and structure of the oil dispersions after steam-heat action and a temperature dependence of viscosity are established. Solvate shells of increased thickness around complex structural unit nuclei and a greater proportion of dispersion medium are distinctive features of the low-viscosity displaced oil. Studies show that the dispersion medium impacts greatly the formation and properties of the oil dispersion. Benzene in the displacing agent decreases the degree of dispersion of the system and the viscosity of the displaced oil.