Field Of Oil Research Articles

Analysis of the hydrodynamic modeling market under the environmental conservation concept

The paper presents a comprehensive analysis of the global software market for modeling technological processes in the field of oil and gas based on data from independent analytical agencies. The work covers various aspects of the industry through a study of key competitors. The paper also provides a better understanding of the meaning of modeling software implementation. The assessment of the potential of the domestic market (TAM-SAM-SOM method) was carried out and the expediency of introducing Russian software for hydrodynamic modeling of high-viscosity oil was substantiated.

Research on Convolutional Neural Network in the Field of Oil and Gas Exploration

Research on Convolutional Neural Network in the Field of Oil and Gas Exploration

PEA–Kerr Combined Measurement Method for Space Charge and Electric Field Distribution of Oil–Paper Composite Insulation

The distribution of space charge and electric field of oil–paper composite insulation is of great importance to the operation and design of converter transformers. However, the widely used pulsed electric-acoustic (PEA) method and Kerr method are difficult to measure the structure of thick pressboard + oil independently. In this article, a PEA–Kerr combined measurement method is proposed. It can not only compensate for each other’s shortcomings but also correct the effects of ultrasonic attenuation on space charge measurement by combining the two measurement signals. By integrating and optimizing the system structure and signal processing methods of PEA and Kerr measurement, the PEA–Kerr combined measurement system is built. The test results show that the system has good linearity, the spatial resolution of the electroacoustic measurement part is 8.8%, and the maximum error of the electrooptic measurement part is 2.5%. Finally, the system is used to measure the structure of 2-mm pressboard + 3-mm oil gap. The relationship between the distribution of space charge and the interface charge density under different voltage amplitudes and polarities is analyzed, and the influence of electric field distortion caused by space charge on the interface charge measurement of oil–paper composite insulation is revealed. This article can provide a basis for measuring and analyzing the distribution of space charge and electric field on thick and complex structures.

Performance improvement of PDC and PDC bits by cryogenic treatment

Polycrystalline diamond compact (PDC) is one of the most widely used cutting tools in the field of oil and gas drilling. In this paper, PDC was cryogenically treated at temperature of around −190 °C and then the mechanical properties such as microhardness, wear ratio, and impact toughness after cryogenic treatment were tested. The morphology, elemental composition and crystal structure of the PDC was investigated by scanning electron microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-ray diffraction (XRD). Meanwhile, the residual stress of the PCD layer was analyzed using Raman spectroscopy. Untreated and cryogenically treated PDC were respectively fabricated into drill bits and the drilling performance were tested. The results showed that the average microhardness of the PDC after cryogenic treatment was increased by 5.3GPa/10.4%, the maximum wear ratio was increased by 11.8%, and the impact toughness was greatly improved to reach 420 J and increased by 79.4% on average. The average rate of penetration (ROP) of the bit equipped with untreated PDC was 1.03 m/h, while the ROP of the bit equipped with cryogenically treated PDC was 1.56 m/h, increased by 51.4%. Microscopic characterization revealed that the change of fracture mode and the evolution of residual stress in PDC was the main mechanism for the improvement of mechanical properties.

Frictional Pressure Drop for Gas–Liquid Two-Phase Flow in Coiled Tubing

Coiled tubing (CT) is widely used in drilling, workover, completion, fracturing and stimulation in the field of oil and gas exploration and development. During CT operation, the tubing will present a gas–liquid two-phase flow state. The prediction of frictional pressure drop for fluid in the tube is an important part of hydraulic design, and its accuracy directly affects the success of the CT technique. In this study, we analyzed the effects of the gas void fraction, curvature ratio and fluid inlet velocity on frictional pressure drop in CT, numerically. Experimental data verified simulated results. Flow friction sensitivity analysis shows the frictional pressure drop reaches its peak at a gas void fraction of 0.8. The frictional pressure gradient increases with the increase in curvature ratio. As the strength of secondary flow increases with the increase in inlet velocity, the increased trend of gas–liquid two-phase flow friction is aggravated. The correlation of friction factor for gas–liquid two-phase flow in coiled tubing is developed by regression analysis of simulation results. The research results can support high quality CT hydraulics design, through which the success of CT operations can be guaranteed.

Assessment of CHINA'S contribution to the development of the russian electric power industry: from planned to implemented projects

Modern energy cooperation between Russia and China is mutually beneficial and complementary: China invests in the implementation of Russian energy projects, and Russia, in turn, supplies its energy resources to China, meeting the needs of both sides. This article assesses China's contribution to the development of the Russian electric power industry. The assessment is carried out on the basis of careful examination of upcoming and already implemented projects of China's investment cooperation in Russia in the field of renewable energy, including solar, wind, and hydropower, as well as in the field of thermal and nuclear energy. At the same time attention is paid to the volume of investment in specific projects, and the degree of participation in the equity holding. Based on the results of the assessment, a conclusion is made about the high interest of China in the implementation of electric power projects in Russia. China especially counts on mutual support for cooperation in the field of renewable energy, namely in the sector of construction of solar, wind and hydropower plants, in order to solve the climate issue. At the same time China does not deny the importance of developing relations in the field of oil and gas.

Template-free hydrothermal synthesis of hollow alumina microspheres and its excellent catalytic properties for thiolation

In view of the important industrial application value of alumina supports in the field of oil refining and reforming, it is of great significance to develop a simple and economical synthesis method for the hierarchical porous alumina. Herein, the hollow microsphere alumina was hydrothermally synthesized without template. The surface of the hollow microsphere alumina supports has a raised fluffy structure, the microsphere diameter is about 5 ∼ 8 μm, and the thickness of the shell is about 1 μm. The morphology evolution process from solid microspheres to core–shell microspheres with spindle-shaped nanoclusters, and then to hollow fluffy microspheres with protruding surface was observed by investigating the effect of hydrothermal synthesis temperature on the morphology of microspheres. Because of its specific morphology and surface characteristics, the microsphere can better disperse the active component KW to prepare KW/Al2O3 catalyst and used in the thiolation to methyl mercaptan. Compared with our previously used catalysts prepared from commercial alumina, this KW/Al2O3 catalyst was not only able to greatly reduce the amount of active component, but also exhibited higher CH3SH selectivity. On the 10KW/Al catalyst, the CH3SH selectivity reached 66.2 % at 340 °C, which was about 10 % higher than that of the previous commercial alumina catalyst. This work can provide theoretical basis and practical guidance for the reasonable design of new alumina support and high efficiency methyl mercaptan catalyst.

A Fiber Bragg Grating accelerometer with cantilever beam

A Fiber Bragg Grating (FBG) accelerometer with cantilever beam is presented and experimentally demonstrated. The effective length of the optical fiber is reduced by changing the base of the accelerometer, so as to increase the sensitivity. The resonant frequency and the sensitivity of the accelerometer are deduced theoretically. The structural parameters were optimized by numerical simulations and the characteristics of the accelerometer were simulated by finite element simulations. The experimental results show that the resonant frequency of the accelerometer is 119 Hz, the sensitivity (the main direction z) is 134.29 pm/g within 2–60 Hz flat region. It also designed with good immunity to interference, the cross sensitivity in the x and the y directions are 3.86 % and 2.97 %, respectively. In addition, the accelerometer has the characteristics of small volume and easy processing. In general, this accelerometer has a research significance in the field of oil and gas exploration.

High-frequency sequences, geochemical characteristics, formations, and distribution predictions of the lower Cambrian Yuertusi Formation in the Tarim Basin

Deep–ultradeep carbonates have long been a hotspot in the field of oil and gas exploration in the Tarim Basin. The hydrocarbon source rock distribution is a key factor restricting deep–ultradeep oil and gas exploration, and in particular, there has been controversy over the sources of the deep oil and gas in the Tarim Basin. In addition, the black shale sediments of the Yuertusi Formation formed during the important transition period of the Precambrian/Cambrian and recorded globally significant climatic events. Research on this formation is of great scientific value for understanding the changes in the Earth's surface climate system during this major and critical transition period. Based on nine field sections, 36 wells, and 2D and 3D seismic data, this paper analyzes the sedimentary environment and hydrocarbon source rock distribution of the Yuertusi Formation in the Tarim Basin. The results show that the lower Cambrian Yuertusi Formation in the Tarim Basin can be divided into two third-order sequences (SQ1 and SQ2) and five fourth-order sequences (sq1-sq5), which experienced two primary transgressions during the deposition of sq2 and sq4. During the depositional period of sq2, hydrocarbon source rocks with the highest organic carbon content in the entire area formed under the influence of high paleoproductivity and upwelling currents. sq4 formed in the context of a second large-scale transgression, and the depositional center moved to the southwest. The organic matter content in sq4 is lower than that in sq2, but it features an extensive distribution and a large thickness. sq3 and sq5 are shallow-water deposits, primarily gray dolomite and algal dolomite with local argillaceous interlayers, that formed during marine regression phases. sq2 and sq4 of the Yuertusi Formation are primarily deep-water to shallow-water shelf sediments with stable thicknesses and are widely distributed in the slope area of the basin and on the shelf. These two sets of high-quality hydrocarbon source rocks indicate the huge hydrocarbon exploration potential of the deep Cambrian strata in the Tarim Basin. These research results can provide important scientific references for evaluating deep–ultradeep oil and gas resources in the Tarim Basin.

Polymer Gels Used in Oil-Gas Drilling and Production Engineering.

Polymer gels are widely used in oil–gas drilling and production engineering for the purposes of conformance control, water shutoff, fracturing, lost circulation control, etc. Here, the progress in research on three kinds of polymer gels, including the in situ crosslinked polymer gel, the pre-crosslinked polymer gel and the physically crosslinked polymer gel, are systematically reviewed in terms of the gel compositions, crosslinking principles and properties. Moreover, the advantages and disadvantages of the three kinds of polymer gels are also comparatively discussed. The types, characteristics and action mechanisms of the polymer gels used in oil-gas drilling and production engineering are systematically analyzed. Depending on the crosslinking mechanism, in situ crosslinked polymer gels can be divided into free-radical-based monomer crosslinked gels, ionic-bond-based metal cross-linked gels and covalent-bond-based organic crosslinked gels. Surface crosslinked polymer gels are divided into two types based on their size and gel particle preparation method, including pre-crosslinked gel particles and polymer gel microspheres. Physically crosslinked polymer gels are mainly divided into hydrogen-bonded gels, hydrophobic association gels and electrostatic interaction gels depending on the application conditions of the oil–gas drilling and production engineering processes. In the field of oil–gas drilling engineering, the polymer gels are mainly used as drilling fluids, plugging agents and lost circulation materials, and polymer gels are an important material that are utilized for profile control, water shutoff, chemical flooding and fracturing. Finally, the research potential of polymer gels in oil–gas drilling and production engineering is proposed. The temperature resistance, salinity resistance, gelation strength and environmental friendliness of polymer gels should be further improved in order to meet the future technical requirements of oil–gas drilling and production.

Sepiolite@TiO2/Graphene oxide composite membrane for long-term Separation of oily wastewater

Microwave synthesis was taken to synthesis A-SEP@TiO2 which has a steady chemical property. The A-SEP@TiO2 composite materials and GO (with different proportion)were mixed and then pumped on commercial PVDF membranes to filter. Finally, the composite membrane A-SEP@TiO2/GO was obtained Under electrostatic self-assembly. Due to the superhydrophilicity and underwater super hydrophobicity of the surface of A-SEP@TiO2/GO membrane, A-SEP@TiO2/GO composite has shown great potential in the field of oil in water. The separation rates of four different emulsions (petroleum ether, toluene, Mesitylene, n-hexane) are all above 90%. With the steady chemical properties, A-SEP@TiO2/GO composite membrane is able to separate oil from water in harsh environment in long-run. After being immersed in 1 mol/L acid and alkali salt solution for one month respectively, all the sample membranes showed a better stability than commercial PVDF membranes. Also, the oil and water removal flux of A-SEP@TiO2/GO composite membrane only decreased by less than 10%, and that was why the composite membranecan can still maintain good cleaning performance even after ten times’ repetition of experiments,. Moreover, the membrane could efficiently remove dyes and heavy metal ions. Therefore, it has a great application prospect in complex water environment treatment.

Effectiveness of Oil Filling in Tight Sandstone Reservoirs of Yancheng Formation in Ordos Basin

The Ordos basin is one of the important oil-bearing basins in China, with abundant tight sandstone oil resources, wide distribution, and large thickness. It is the most realistic field of unconventional oil and gas exploration in China, and it is also an important oil and gas replacement resource at present. Oil accumulation in tight reservoirs is obviously different from conventional oil and gas accumulation, and the key lies in studying the effectiveness of oil filling in tight reservoirs. In order to solve this problem, this paper takes the tight sandstone reservoir of Member 7 of the Yancheng Formation in Ordos Basin as the research object, introduces the geological characteristics of this area after sorting out the previous research results, carries out the physical simulation experiment of oil filling, studies the relationship between the filling pressure and the lower limit of the filling throat, analyzes the effective accumulation space of the tight sandstone reservoir, defines the oil filling mechanism of the tight sandstone reservoir, and discusses the effectiveness and reservoir-forming effect of oil filling in different types of reservoirs. The results show that the rock types of tight sandstone reservoirs in the 7th member of the Yancheng Formation are mainly lithic feldspathic sandstone and feldspathic lithic sandstone, and the reservoirs have experienced strong compaction and carbonate cementation. The late iron-bearing carbonate cementation has further strengthened the degree of reservoir densification, and the reservoirs have been densified at the time of large-scale oil and gas filling. Through the simulation experiment of oil filling with natural cores with different physical properties, the relationship model between filling pressure and effective accumulation space of different types of tight sandstone reservoirs in Member 7 of the Yancheng Formation is established. With the change in filling pressure, the change trend and range of effective accumulation space of different types of tight sandstone reservoirs are obviously different. According to the relationship model between the filling pressure and the lower limit of the effective filling pore throat, the oil filling effectiveness of different types of tight sandstone reservoirs in the 7th member of the Yancheng Formation is determined. Class I and class II1 reservoirs are effective reservoirs for oil filling of tight sandstone reservoirs, which constitute the main oil-bearing section of tight sandstone reservoirs in member 7 of the Yancheng formation, while class II2 reservoirs are poor tight reservoirs, and class III reservoirs are basically oil-free, which are noneffective reservoirs for oil filling of tight sandstone reservoirs. The results provide theoretical data support for the next step of oil exploration and exploitation in tight sandstone reservoirs.

Double network self-healing hydrogel based on hydrophobic association and ionic bond for formation plugging

Self-healing hydrogels have attracted tremendous attention in the field of oil and gas drilling and production engineering because of their excellent self-healing performance after physical damage. In this study, a series of double network self-healing (DN SA ) hydrogels based on hydrophobic association and ionic bond were prepared for plugging pores and fractures in formations in oil and gas drilling and production engineering. The mechanical, rheological, and self-healing properties of the DN SA hydrogels were investigated. Results revealed that the DN SA hydrogels exhibited excellent mechanical properties with a tensile stress of 0.67 MPa and toughness of 7069 kJ/cm 3 owing to the synergistic effect of the double network. In addition, the DN SA hydrogels exhibited excellent compression resistance, notch insensitivity, and self-healing properties. The DN SA -2 hydrogel was granulated and made into gel particles with different particle sizes and used as a plugging agent. The self-healing mechanism of DN SA -2 hydrogel particles in fractures was explored, and it's plugging effect on fractures of different widths and porous media of different permeabilities were investigated. Experimental results revealed that the plugging capacity of the DN SA -2 hydrogel particles for a fracture with width of 5 mm and a porous medium with a permeability of 30 μm 2 was 3.45 and 4.21 MPa, respectively, which is significantly higher than those of commonly used plugging agents in the oilfield. The DN SA hydrogels with excellent mechanical and self-healing properties prepared in this study will provide a new approach for applying hydrogels in oil and gas drilling and production engineering.

Experimental and numerical investigation on conjugate performance of fan and heat exchanger of helicopter oil cooling system

• The overall performance of axial fan was studied with two flowrate adjusting modes. • HEs with different fin structures and flow lengths were designed and fabricated. • Coupling performances of fan and different HEs were studied experimentally. • The flow field of oil cooling system at different air flow rate was simulated. • The performance curves obtained by two modes form a hysteresis region. In this article, a combined experimental and numerical study has been performed to investigate the operating performance of axial fan and oil cooling system. A test rig was established, and six types of plate-fin heat exchangers (HEs) with offset strip and rectangular fins and three different flow lengths of 30 mm, 60 mm and 90 mm at side were designed and manufactured. The performance of an axial fan with front guide vane was experimentally studied by two different adjusting modes: gradually increasing and decreasing air flow rate. The conjugate performances of the axial fan and different HEs were discussed in detail. Moreover, a three-dimensional (3D) model was developed to investigate the flow distribution of the system including fan and 30 mm offset strip fins HE at different flow rates. The results show that: (1) the total pressure performance curve of the axial fan under two adjusting modes could form a hysteresis region near the stall boundary. In the hysteresis region, the fan performance curves showed significant difference under both adjusting modes; (2) when the offset strip fins HE with large flow resistance is considered, the system could have two theoretical working points in the hysteresis region. For the case of HE with 90 mm offset strip fins, the flow rates of the system at two theoretical working points were 25.1 m 3 /min and 34.2 m 3 /min, and the heat transfer capacity of the HE were 23.1 kW and 27.5 kW, respectively. In the current experiment, it was found that the system operated at the point with smaller flow rate; (3) when the HE flow resistance exceeded a certain value, the boundary layer separation of the airflow could occur at the rotor blade. The separation had a small effect on the inlet airflow due to its turbulence kinetic energy was low and basically the same at each blade passage. Therefore, the system did not surge or stall at small flow rate.

Designing an energy security index with a sustainable development approach for energy-exporting countries using fuzzy BWM method.

Energy-exporting countries have always been isolated when it comes to energy security since according to the traditional definition of energy security, it is believed that there are no energy security-associated problems in these countries. Over the recent years, exporting countries have encountered the issue of single-product economy on a much larger scale, due to large oil revenues; they are facing more and more problems in the field of energy security every day. In this regard, the present paper primarily identified the challenges and factors affecting energy security and sustainable development related to energy in these countries. Afterwards, this information was employed for the construction of a composite index to measure the energy security and sustainability in these countries using the fuzzy BWM method. This composite index was utilized for a period of 14years in five energy-exporting countries, namely Iran, Iraq, Russia, Saudi Arabia, and Venezuela. The results obtained herein were fully consistent with the process of the changes in energy security in the mentioned countries and indicated the weaknesses and obstacles of these countries in the field of oil and oil economy. The results of a 14-year evaluation of the composite index show that Saudi Arabia, followed by Russia, Iran, Iraq, and Venezuela, displays the best performance in the field of energy security and sustainability and has an ascending trend and significant progress in the index value. Although Russia is in second place, it represents a descending trend. Iran, which is in third place on the slope of changes, has a falling but gentler trend. Iraq has a rising trend in the index value despite being in fourth place. The lowest level of energy security belongs to Venezuela with a sharp descending trend and naturally the worst performance in the field of energy security and sustainability. Examining these obstacles, it was observed that the economic-technological issues were a heavier burden than the social and environmental ones. In the economic-technological sector, oil-free per capita GDP, the share of non-energy exports in total exports, and the share of investment in the energy sector in total investment were the biggest obstacles, indicating the urgent need to change macro policies, exit the single-product economy, and adopt policies to increase the value added and reduce the sale of raw energy.

Development of low frequency and high sensitivity fiber optic accelerometer based on multi-stage flexure hinges

In order to reduce the stiffness of the flexure hinges, a low-frequency fiber Bragg grating (FBG) accelerometer based on multi-stage flexure hinges is designed. According to the series–parallel connection theory of springs, the acceleration response and anti-interference characteristics of the accelerometer are experimentally studied. The experimental results shows that the accelerometer with multi-stage hinges has a wide flat frequency band and high sensitivity. The resonant frequency is 84.2 Hz, the response sensitivity of the external vibration signal is 927.21 pm/G in the range of 1–60 Hz and the lateral interference degree is 5.8 %. It shows that the acceleration sensing performance of the accelerometer is good. On this basis, changing the hinge radius, thickness or the size of the mass block can further expand the measurement range of the accelerometer, which is expected to be applied in the field of low-frequency oil and gas seismic exploration.

Improvement of Interaction Mechanism between Oil Refining Enterprises and Contractors

Introduction. Major projects in the oil refining industry require the involvement of contractors. Cooperation with qualified and responsible contractors can be considered as a competitive advantage, allowing timely delivery of objects with the proper level of quality and safety.Significant injury rates in contracting organizations operating at oil refining facilities attract attention. This leads to an interest in safety of working conditions in the industry. One of the approaches to solving the problem is to use the occupational health and safety management system in the interactions of the customer and the contractor.Problem Statement. The objective of this study is to improve the mechanism of rating contractors from the point of view of occupational and industrial safety.Theoretical Part. The paper uses the official statistical reports on injuries and the data on injuries of employees of contracting organizations at an oil refinery of a large Russian company. A mechanism for rating contractors in this area has been developed. It includes three sections with their own criteria and weight coefficients. The automatically generated and periodically updated rating is proposed to be placed in open access on the website of the Federal Service for Labor and Employment.Conclusions. The use of the proposed rating will allow customers working in the field of oil refining to reasonably judge the risks generated by the industrial safety system of potential contractors.

Hydrophobic, partially hydrophobic, and hydrophilic ZnO@SiO2 nanoparticles as fluorescent partitioning tracers for oil sensing applications

(a) Schematic representation of various functionalities on the surface of ZnO@SiO 2 nanoparticles. The partially hydrophobic (PH-NPs, S2), hydrophobic (HP-NPs, S3), and hydrophilic (H-NPs, S4) functionalities were developed on the surface of ZnO@SiO 2 NPs using various silanes having methyl, octyl, and amino groups, respectively. (b,c) The fluorescent NPs (S4) stayed entirely in the water phase due to the presence of –NH 2 group (hydrophilic nature), while the fluorescent NPs (S3) moved completely toward the oil phase due to the presence of octyl-group (hydrophobic nature) on their surface. However, the luminescent NPs (S2) were shifted toward the interface between two phases due to partially hydrophobic character ( CH 3 ) on their surface. • ZnO@SiO 2 NPs were synthesized via a modified sol–gel Stober protocol. • Surface functionalities were attained by co-condensation of various silanes. • Surface chemistry and partitioning behavior of ZnO@SiO 2 NPs were investigated. • ZnO@SiO 2 NPs have excellent fluorescence stability in aqueous environments. • Stability of ZnO@SiO 2 NPs was examined under harsh reservoir conditions. Fluorescent nano-tracers are being utilized for oil sensing applications in the reservoir. In this work, we developed various hydrophobic, partially hydrophobic, and hydrophilic zinc oxide encapsulated silica nanoparticles (ZnO@SiO 2 NPs) as smart nano-agents for oil sensing applications. The surface of ZnO@SiO 2 NPs was functionalized by co-condensation using various silanes in combination with tetraethyl orthosilicate (TEOS). Cryogenic TEM images display the average size of ZnO QDs (S0) and ZnO@SiO 2 nanoparticles (S1) around ∼5.3 nm and ∼50 nm, respectively. The surface chemistry and partitioning behavior of photoluminescent ZnO@SiO 2 NPs were investigated before and after mixing with the model oil under normal and UV light. The chemical and photoluminescence (PL) stability of ZnO@SiO 2 NPs was monitored in harsh reservoir conditions, such as variable temperature (30–100 °C) and high salinity (0–80 g L −1 ) environment. The results demonstrated that the surface modification and functionalization of these nano-agents with different functional groups (methyl, octyl) improved the nano-agents’ selectivity and stability after changing their hydrophilic-hydrophobic surface characters. This work is opening new research in the field of oil sensing, which promotes their potential utilization as cost-effective and efficient fluorescent tracer materials for the oil exploration industries.

Mg-calcite CaCO3 particle: Rapid synthesis and application in fabrication of environmentally friendly hydrophobic polyurethane sponge for oil–water separation

The hydrophobic modification of polyurethane (PU) sponge is attracting considerable attention in the field of oil–water separation. A hydrophobic PU sponge with microsize cavities on the skeleton surface and interior was prepared with hierarchical structural Mg-calcite CaCO3 (MCC) particles as a template. Hydrophobic-modified MCC particles with controllable morphologies were firstly synthesized by a facile and rapid batch method under high-speed stirring for 1 min by the presence of cetyltrimethyl ammonium bromide. MCC particles were then blended into the starting foaming materials to fabricate hydrophobic PU/MCC sponge by in-situ polymerization method. Finally, MCC particles of PU/MCC sponge were etched by acid solution and microsize cavities were generated on the surface and interior of EPU/MCC sponge skeleton. The oil-adsorption capacity of obtained hydrophobic EPU/MCC sponge was 7.58 and 5.31 times higher than pristine PU sponge for engine oil and sunflower oil, respectively. This could be attributed to the microsize cavities on the skeleton surface and interior which would increase the skeleton flexibility and enhance adhesion level between the oil and sponge surface. The underwater CCl4 was completely adsorbed into the EPU/MCC sponge within 1 s, indicating its high adsorption speed. EPU/MCC sponge exhibited high separation selectivity and separation efficiency in gravity-driven oil-water separation. The results could provide a strategy to develop hydrophobic sponges with excellent oil-water separation property.

Comparative analysis of the static adsorption of oil droplets and the dynamic absorption capacity of their aggregates by cotton, kapok, cattail and flax fibers

Natural fiber has the advantages of being abundant, renewable and biodegradable, and it will be very promising to use it in the field of oil absorption. The adsorption and absorption process of engine oil, waste oil and salad oil were observed and quantitatively characterized by using four natural fibers of cotton, kapok, cattail and flax fiber. The main reason for the different forms of adsorbed oil droplets is that the static contact angles of the four fibers have little difference in the three oils, which further proves that flax is both lipophilic and hydrophilic. Judging from the shape of the oil droplets absorbed by the four types of fiber flakes, because the fibers changed from the local wetting state to the diffusion and expansion stage, and finally reached a stable state of saturation, the immersion time of the first half of the circle was much lower than that of the second half. The analysis of the influencing factors, such as the wax content on the fiber surface and the viscosity and tension of the oil, provides a theoretical reference for the application of natural fibers in the field of oil and sewage treatment.