In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypro...In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.展开更多
Recently, deep eutectic solvents (DES) have received great attention in assisting water flooding and surfactant flooding to improve oil recovery because they can reduce the interfacial tension (IFT) between oil and wa...Recently, deep eutectic solvents (DES) have received great attention in assisting water flooding and surfactant flooding to improve oil recovery because they can reduce the interfacial tension (IFT) between oil and water, inhibit surfactant adsorption, and change the wettability of rock. However, the effects of DES on the wettability of rock surface have not been thoroughly investigated in the reported studies. In this study, the effects of various DES samples on the wettability of sandstone samples are investigated using the Amott wettability measurement method. Three DES samples and several DES solutions and DES-surfactant solutions are firstly synthesized. Then, the wettability of the sandstone samples is measured using pure saline water, DES solutions, and DES-surfactant solutions, respectively. The effects of the DES samples on the wettability of the sandstone samples are investigated by comparing the measured wettability parameters, including oil displacement ratio (I_(o)), water displacement ratio (I_(w)), and wettability index (I_(A)). The Berea rock sample used in this study is weakly hydrophilic with I_(o), I_(w), and I_(A) of 0.318, 0.032, and 0.286, respectively. Being processed by the prepared DES samples, the wettability of the Berea sandstone samples is altered to hydrophilic (0.7 > I_(A) > 0.3) by increasing I_(w) but lowering Io. Similarly, DES-surfactant solutions can also modify the wettability of the Berea sandstone samples from weakly hydrophilic to hydrophilic. However, some DES-surfactant solutions can not only increase I_(w) but also increase I_(o), suggesting that the lipophilicity of those sandstone samples will be improved by the DES-surfactant solutions. In addition, micromodel flooding tests confirm the promising performance of a DES-surfactant solution in improving oil recovery and altering wettability. Moreover, the possible mechanisms of DES and DES-surfactant solutions in altering the wettability of the Berea sandstone samples are proposed. DES samples may improve the hydrophilicity by forming hydrogen bonds between rock surface and water molecules. For DES-surfactant solutions, surfactant micelles can capture oil molecules to improve the lipophilicity of those sandstone samples.展开更多
As the main factor influencing the flow and preservation of underground fluids,wettability has a profound impact on CO_(2)sequestration(CS).However,the influencing factors and internal interaction mechanisms of shale ...As the main factor influencing the flow and preservation of underground fluids,wettability has a profound impact on CO_(2)sequestration(CS).However,the influencing factors and internal interaction mechanisms of shale kerogen wettability remain unclear.In this study,we used molecular dynamics to simulate the influence of temperature,pressure,and salinity on wettability.Furthermore,the results were validated through various methods such as mean square displacement,interaction energy,electrostatic potential energy,hydrogen bonding,van der Waals forces,and electrostatic forces,thereby confirming the reliability of our findings.As temperature increases,water wettability on the surface of kerogen increases.At CO_(2)pressures of 10 and 20 MPa,as the temperature increases,the kerogen wettability changes from CO_(2)wetting to neutral wetting.As the CO_(2)pressure increases,the water wettability on the surface of kerogen weakens.When the pressure is below 7.375 MPa and the temperature is 298 or 313 K,kerogen undergoes a wettability reversal from neutral wetting to CO_(2)wetting.As salinity increases,water wettability weakens.Divalent cations(Mg2+and Ca2+)have a greater impact on wettability than monovalent cations(Na^(+)).Water preferentially adsorbs on N atom positions in kerogen.CO_(2)is more likely to form hydrogen bonds and adsorb on the surface of kerogen than H_(2)O.As the temperature increases,the number of hydrogen bonds between H_(2)O and kerogen gradually increases,while the increase in pressure reduces the number of hydrogen bonds.Although high pressure helps to increase an amount of CS,it increases the permeability of a cap rock,which is not conducive to CS.Therefore,when determining CO_(2)pressure,not only a storage amount but also the storage safety should be considered.This research method and results help optimize the design of CS technology,and have important significance for achieving sustainable development.展开更多
Wettability has complex effects on the physical properties of reservoir rocks.The wettability of rocks should be characterized accurately to explore and develop oil and gas.Researchers have studied the rock wettabilit...Wettability has complex effects on the physical properties of reservoir rocks.The wettability of rocks should be characterized accurately to explore and develop oil and gas.Researchers have studied the rock wettability by dielectric spectra which contained abundant information.To study the rock wettability from dielectric dispersion,four rock samples with different wettabilities were used to design an experimental measurement flow.The relative dielectric permittivity in the frequency range of 100 Hz-10MHz and nuclear magnetic resonance T_(2)spectra of the samples were obtained.Subsequently,the wettabilities of the rocks were verified by the T_(2)spectra.The dielectric dispersions of the samples under different conditions were analyzed.Furthermore,the simulated-annealing(SA)algorithm was used to invert the wettability and related parameters of the rocks by a dielectric dispersion model.The results indicated that the dielectric permittivity of lipophilic rocks is lower than that of hydrophilic rocks,and that the dielectric permittivity of hydrophilic rocks decreases faster as the frequency increases.The dielectric permittivity in the high-frequency band is associated with the water content.The rock wettability parameters obtained via inversion agreed well with the T_(2)spectra,and the saturation index of the rocks.The errors between the rock permittivity calculated by the inverted parameters and the experimentally measured values were minor,indicating that rock wettability could be accurately characterized using dielectric dispersion data.展开更多
Bubble nucleation plays a crucial role in boiling heat transfer and other applications.Traditional experiments struggle to capture its microscopic mechanisms,making molecular dynamics simulations a powerful tool for s...Bubble nucleation plays a crucial role in boiling heat transfer and other applications.Traditional experiments struggle to capture its microscopic mechanisms,making molecular dynamics simulations a powerful tool for such studies.This work uses molecular dynamics simulations to investigate bubble nucleation of water on copper surfaces with sinusoidal groove roughness under varying heat flux and surface wettability.Results show that at the same wettability,higher heat flux leads to higher surface temperatures after the same heating time,promoting bubble nucleation,growth,and departure.Moreover,under constant heat flux,stronger surface hydrophilicity enhances heat transfer from the solid to the liquid,further accelerating the nucleation.This study provides valuable insights into the mechanism of bubble nucleation and offers theoretical guidance for enhancing heat transfer.展开更多
The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequentl...The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequently,low-energy anti/de-icing methods based on superhydrophobic surfaces have attracted widespread attention.Previous studies have demonstrated that for stationary components,superhydrophobic surfaces can significantly reduce anti-icing energy consumption by altering the flow behavior of runback water.However,for rotating inlet components of aero-engines,the effectiveness of superhydrophobic surfaces and the influence of surface wettability on the evolution of runback water flow remain unclear due to the effects of centrifugal and Coriolis forces.This study establishes a 3D liquid water flow simulation model using the volume of fluid(VOF)method to investigate the effects of rotational speed,airflow velocity,and surface wettability on the runback water flow behavior over the rotating spinner under dynamic rotation conditions.The results show that the rotational effects and surface wettability mutually reinforce one another.Specifically,increasing the rotational speed and contact angle can both enhance the flow velocity of liquid water and accelerate the breakup and rupture of liquid film,leading to the formation of rivulets,droplets,and subsequent detachment from the surface.A theoretical model based on force balance is proposed to describe the evolution of runback water flow,and the analysis reveals that as the rotational speed and contact angle increase,the water film is more likely to break up to form rivulets and beads,and the critical radius for droplet detachment from the surface decreases,making it easier removal from the surface.展开更多
The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes(PHPs)under three modified surfaces(superhydrophilic evaporation secti...The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes(PHPs)under three modified surfaces(superhydrophilic evaporation section paired with superhydrophilic,superhydrophobic,and hybrid condensation section).The Volume of Fluid(VOF)model was utilized to capture the phase-change process within the PHPs.The study also evaluated the influence of surface wettability on fluid patterns and thermo-dynamic heat transfer performance under various heat fluxes.The results indicated that the effective nucleation and detachment of droplets are critical factors influencing the thermal performance of the PHPs.The overall heat transfer performance of the superhydrophobic surface was significantly improved at low heat flux.Under medium to high heat flux,the superhydrophilic condensation section exhibits a strong oscillation effect and leads to the thickening of the liquid film.In addition,the hybrid surface possesses the heat transfer characteristics of both superhydrophilic and superhydrophobic walls.The hybrid condensation section exhibited the lowest thermal resistance by 0.45 K/W at the heat flux of 10731 W/m^(2).The thermal resistance is reduced by 13.1%and 5.4%,respectively,compared to the superhydrophobic and superhydrophilic conditions.The proposed surface-modification method for achieving highly efficient condensation heat transfer is helpful for the design and operation of device-cooling components.展开更多
We presented a novel porous alumina ceramics(PACs)with superoleophilicity and superoleo-phobicity when immersed in different oil-water environments.The wettability,separation efficiency,permeation flux and reusability...We presented a novel porous alumina ceramics(PACs)with superoleophilicity and superoleo-phobicity when immersed in different oil-water environments.The wettability,separation efficiency,permeation flux and reusability of the PACs for oil/water separation were investigated and characterized via extensive ex-periments.The PACs material had favourable properties including mechanical strength and chemical durability compared with fabric-based materials and organic sponge-based materials previously reported in literature for oil/water separation.It is believed that the PACs material and methodology presented in this work may provide wastewater remediation industry with a promising alternative for dealing with the catastrophic ocean oil pollu-tion and other oil contamination.展开更多
Herein,an alkyne-terminated acid/base responsive amphiphilic [2]rotaxane shuttle was synthesized,and then modified onto the glass surface through “click” reaction.The XPS N 1s spectrum and contactangle measurement w...Herein,an alkyne-terminated acid/base responsive amphiphilic [2]rotaxane shuttle was synthesized,and then modified onto the glass surface through “click” reaction.The XPS N 1s spectrum and contactangle measurement were performed to prove the successful immobilization.The amphiphilic [2]rotaxane functionalized surface presented controllable wettability responding to external acid-base stimuli.This bistable rotaxane modified material system promoted the practical application of molecular machines.展开更多
The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)us...The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)using the Capillary Purification(CP)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)procedure.The high-temperature tests were performed under isothermal conditions(CP:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) atmosphere.During the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate couples.Scanning and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified couples.It was found that an oxide-free Mg drop obtained by the CP procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθ<90°in<1 s),followed by fast spreading and good wetting over the Ni substrate(θ_((CP))~20°in 5 s)to form a final contact angle ofθ_(f(CP))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test temperature.However,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.展开更多
Inspired by the skin structure,an asymmetric wettability tri-layer nanofiber membrane(TNM)consisting of hydrophilic inner layer loaded with lidocaine hydrochloride(LID),hydrophobic middle layer with ciprofloxacin(CIP)...Inspired by the skin structure,an asymmetric wettability tri-layer nanofiber membrane(TNM)consisting of hydrophilic inner layer loaded with lidocaine hydrochloride(LID),hydrophobic middle layer with ciprofloxacin(CIP)and hydrophobic outer layer has been created.The hydrophobic outer layer endows the TNM with waterproof function and anti-adhesion from contaminants.The hydrophobic middle layer with CIP preserves long-term inhibition of bacteria growth and the hydrophilic inner layer with LID possesses optimal waterabsorbing capacity and air permeability.The TNM dramatically elevates the water contact angles from 10°(inner layer)to 120(outer layer),indicating an asymmetric wettability,which could directionally transport wound exudate within the materials and meanwhile maintain a comfortable and moist environment to promote wound healing.Furthermore,the sequential release of LID and CIP could relieve pain rapidly and achieve antibacterial effect in the long run,respectively.In addition,the TNM shows superior biocompatibility towards L929 cells.The in vivo results show the TNM could prevent infection,accelerate epithelial regeneration and significantly accelerate wound healing.This study indicates the developed TNM with asymmetrical wettability and synergetic drug release shows great potential as a wound dressing in clinical application.展开更多
Thermoregulatory textiles,leveraging high-emissivity structural materials,have arisen as a promising candidate for personal cooling management;however,their advancement has been hindered by the underperformed water mo...Thermoregulatory textiles,leveraging high-emissivity structural materials,have arisen as a promising candidate for personal cooling management;however,their advancement has been hindered by the underperformed water moisture transportation capacity,which impacts on their thermophysiological comfort.Herein,we designed a wettability-gradient-induced-diode(WGID)membrane achieving by MXene-engineered electrospun technology,which could facilitate heat dissipation and moisture-wicking transportation.As a result,the obtained WGID membrane could obtain a cooling temperature of 1.5℃ in the“dry”state,and 7.1℃ in the“wet”state,which was ascribed to its high emissivity of 96.40%in the MIR range,superior thermal conductivity of 0.3349 W m^(-1) K^(-1)(based on radiation-and conduction-controlled mechanisms),and unidirectional moisture transportation property.The proposed design offers an approach for meticulously engineering electrospun membranes with enhanced heat dissipation and moisture transportation,thereby paving the way for developing more efficient and comfortable thermoregulatory textiles in a high-humidity microenvironment.展开更多
The production of renewable fuels through water splitting via photocatalytic hydrogen production holds significant promise.Nonetheless,the sluggish kinetics of hydrogen evolution and the inadequate water adsorption on...The production of renewable fuels through water splitting via photocatalytic hydrogen production holds significant promise.Nonetheless,the sluggish kinetics of hydrogen evolution and the inadequate water adsorption on photocatalysts present notable challenges.In this study,we have devised a straightforward hydrothermal method to synthesize Bi_(2)O_(3)(BO)derived from metal‐organic frameworks(MOFs),loaded with flower-like ZnIn_(2)S_(4)(ZIS).This approach substantially enhances water adsorption and surface catalytic reactions,resulting in a remarkable enhancement of photocatalytic activity.By employing triethanolamine(TEOA)as a sacrificial agent,the hydrogen evolution rate achieved with 15%(mass fraction)ZIS loading on BO reached an impressive value of 1610μmol∙h^(−1)∙g^(−1),marking a 6.34-fold increase compared to that observed for bare BO.Furthermore,through density functional theory(DFT)and ab initio molecular dynamics(AIMD)calculations,we have identified the reactions occurring at the ZIS/BO S-scheme heterojunction interface,including the identification of active sites for water adsorption and catalytic reactions.This study provides valuable insights into the development of high-performance composite photocatalytic materials with tailored electronic properties and wettability.展开更多
Disgusting deposits(e.g.,scale and crude oil)in daily life and industrial production are always serious problems,posing great threats to the safety and economic development.However,most of developed coatings can only ...Disgusting deposits(e.g.,scale and crude oil)in daily life and industrial production are always serious problems,posing great threats to the safety and economic development.However,most of developed coatings can only conquer one part of these deposits such as superhydrophobic coatings possess antiscaling capacity but would adhere crude oil.To integrate scale resistance with oil repellence,we herein report a robust superamphiphobic(SAB)coating simultaneously reducing pollution of scale and oil for extended period of time(two weeks with over 98%reduction).Compared with single role of superhydrophobic and amphiphilic surfaces,the SAB coating can not only inhibit interfacial nucleation of scale but also reduce the adhesion of formed scale and polluted oil.The durability of the SAB coating is evaluated via mechanical tests(sandpaper abrasion,tape stripping and sand falling)and chemical corrosion(corrosive liquid immersing),revealed by sustainable high contact angles and low contact angle hysteresis of water and oil.The universality of this strategy can be further confirmed by adding different particles like kaolin,Al_(2)O_(3),and SiO_(2),resisting multiple types of scale(i.e.,CaSO_(4),BaSO_(4)and MgCO_(3))and oil(i.e.,glycerol,glycol,and mineral oil).Therefore,this study provides an ideal avenue for resisting scale and oil,which may be used for conquering the complexity of application environments(e.g.,oil production and transportation).展开更多
The sodium smelting of vanadium-titanium magnetite can achieve the comprehensive utilization of Fe,V,and Ti.However,the generation of alkaline slag during this process may cause damage to refractory materials.The wett...The sodium smelting of vanadium-titanium magnetite can achieve the comprehensive utilization of Fe,V,and Ti.However,the generation of alkaline slag during this process may cause damage to refractory materials.The wettability and corrosion behavior of alkaline slag on three types of refractory(MgO-C,SiC,and high alumina refractory)substrates were investigated at temperatures up to 1200℃.The effects of duration on the wettability of molten slag on SiC substrates were also investigated.Results showed that the high alumina refractory exhibited better wettability with the molten slag than the others,and thus,it is easier to be corroded.The results of scanning electron microscopy coupled with energy dispersive spectroscopy showed that MgO-C and high alumina refractory substrates were severely eroded.There was a visible and regular interfacial reaction layer between the slag and SiC refractory substrate,which was produced by the redox reaction between the metal oxides in the slag and the SiC refractory substrate.With the increase in holding time,the interface layer expands and silico-ferrite phases are generated at the interface.The redox reaction between Fe_(2)O_(3) and SiC substrate is the main reason for the corrosion.By comparing the differences in wettability and corrosion behavior between the alkaline slag from sodium smelting of vanadium-titanium magnetite and MgO-C,SiC and high alumina refractories,it is concluded that SiC refractory has good corrosion resistance to the slag.Iron oxides in the slag accelerate the oxidation rate of SiC refractory.展开更多
The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of ...The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of the wettability and interface characteristics between the reinforcing phase and the bulk metallic glasses(BMGs).This work optimized the composition of Zr-based BMGs through microalloying methods,resulting in a new set of Zr-based BMGs with excellent glass-forming ability.Wetting experiments between the Zr-based BMGs melts and W substrates were conducted using the traditional sessile drop method,and the interfaces were characterized utilizing a scanning electron microscope(SEM)equipped with energy dispersive X-ray spectroscopy(EDS).The work demonstrates that the microalloying method substantially enhances the wettability of the Zr-based BMGs melt.Additionally,the incorporation of Nb element impedes the formation of W-Zr phases,but the introduction of Nb element does not alter the extent of interdiffusion between the constituent elements of the amorphous matrix and W element,indicating that the influence of Nb element on the diffusion of individual elements is minute.展开更多
A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2spectrum,and the time-varying law of simulated oil viscosity in por...A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2spectrum,and the time-varying law of simulated oil viscosity in porous media is quantitatively characterized by nuclear magnetic resonance(NMR)experiments of high multiple waterflooding.A new NMR wettability index formula is derived based on NMR relaxation theory to quantitatively characterize the time-varying law of rock wettability during waterflooding combined with high-multiple waterflooding experiment in sandstone cores.The remaining oil viscosity in the core is positively correlated with the displacing water multiple.The remaining oil viscosity increases rapidly when the displacing water multiple is low,and increases slowly when the displacing water multiple is high.The variation of remaining oil viscosity is related to the reservoir heterogeneity.The stronger the reservoir homogeneity,the higher the content of heavy components in the remaining oil and the higher the viscosity.The reservoir wettability changes after water injection:the oil-wet reservoir changes into water-wet reservoir,while the water-wet reservoir becomes more hydrophilic;the degree of change enhances with the increase of displacing water multiple.There is a high correlation between the time-varying oil viscosity and the time-varying wettability,and the change of oil viscosity cannot be ignored.The NMR wettability index calculated by considering the change of oil viscosity is more consistent with the tested Amott(spontaneous imbibition)wettability index,which agrees more with the time-varying law of reservoir wettability.展开更多
Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stabilit...Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in oil.Herein we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil(W/O)emulsion.Silanes with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface wettabilities.While all the modified membranes exhibited excellent separation of the W/O without Span 80(surfactant),the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/O.The presence of Span 80 reduced the interfacial tension of water droplets,making them easier to deform and penetrate the modified membrane with the lowest surface energy.It reveals that engineering proper surface wettability is the key to separating the oil and water phases.Besides,the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.展开更多
Multiphase flow in low permeability porous media is involved in numerous energy and environmental applications.However,a complete description of this process is challenging due to the limited modeling scale and the ef...Multiphase flow in low permeability porous media is involved in numerous energy and environmental applications.However,a complete description of this process is challenging due to the limited modeling scale and the effects of complex pore structures and wettability.To address this issue,based on the digital rock of low permeability sandstone,a direct numerical simulation is performed considering the interphase drag and boundary slip to clarify the microscopic water-oil displacement process.In addition,a dual-porosity pore network model(PNM)is constructed to obtain the water-oil relative permeability of the sample.The displacement efficiency as a recovery process is assessed under different wetting and pore structure properties.Results show that microscopic displacement mechanisms explain the corresponding macroscopic relative permeability.The injected water breaks through the outlet earlier with a large mass flow,while thick oil films exist in rough hydrophobic surfaces and poorly connected pores.The variation of water-oil relative permeability is significant,and residual oil saturation is high in the oil-wet system.The flooding is extensive,and the residual oil is trapped in complex pore networks for hydrophilic pore surfaces;thus,water relative permeability is lower in the water-wet system.While the displacement efficiency is the worst in mixed-wetting systems for poor water connectivity.Microporosity negatively correlates with invading oil volume fraction due to strong capillary resistance,and a large microporosity corresponds to low residual oil saturation.This work provides insights into the water-oil flow from different modeling perspectives and helps to optimize the development plan for enhanced recovery.展开更多
Adhesion of oil at rock surface plays an important role in the liberation of oil from micro-/nano-pores,especially for heavy oil that has extremely high viscosity.Although molecular dynamics simulation is widely used ...Adhesion of oil at rock surface plays an important role in the liberation of oil from micro-/nano-pores,especially for heavy oil that has extremely high viscosity.Although molecular dynamics simulation is widely used to study the interfacial interaction for some specific oil-water-rock systems,experimental measurements provide more realistic and reliable evidence.In this work,we propose a dynamic wettability characterization method to indirectly measure resistant forces at oil-surfactant-rock interfaces,including frictional force,wettability hysteresis force,and viscous force,which are parallel with the oil-solid interface.The adhesive force,which is normal to the oil-solid interface is calculated through measurement of work of adhesion.The results show that work of adhesion instead of contact angle can better describe the adhesion of oil at solid surface.The effect of surfactant concentration on work of adhesion is different for water-wet and oil-wet surfaces.Moreover,average viscous forces are calculated through force analysis on oil drops moving along solid surface in different surfactant environments.It is found that viscous force has a magnitude comparable to the frictional force during the movement,while the wettability hysteresis force is negligible.On the other hand,the adhesive force calculated from the work of adhesion is also comparable to the viscous force.Therefore,both the resistant forces parallel with and normal to the oil-solid interface should be minimized for the liberation of oil from rock surface.This work proposes a simple method to evaluate the wetting capability of different surfactants and measure the adhesive force between heavy oil and rock surfaces indirectly,which provides insight into the adhesion of heavy oil at rock surface and would be valuable for the development of surfactant-based oil recovery methods.展开更多
文摘In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.
基金supported by the Scientific Research and Technology Development Projects of PetroChina(2023ZZ22-02)the Local Efficient Reform and Development Funds for Personnel Training Projectsthe China Scholarship Council(CSC)via a Ph.D.Scholarship(No.202008510128).
文摘Recently, deep eutectic solvents (DES) have received great attention in assisting water flooding and surfactant flooding to improve oil recovery because they can reduce the interfacial tension (IFT) between oil and water, inhibit surfactant adsorption, and change the wettability of rock. However, the effects of DES on the wettability of rock surface have not been thoroughly investigated in the reported studies. In this study, the effects of various DES samples on the wettability of sandstone samples are investigated using the Amott wettability measurement method. Three DES samples and several DES solutions and DES-surfactant solutions are firstly synthesized. Then, the wettability of the sandstone samples is measured using pure saline water, DES solutions, and DES-surfactant solutions, respectively. The effects of the DES samples on the wettability of the sandstone samples are investigated by comparing the measured wettability parameters, including oil displacement ratio (I_(o)), water displacement ratio (I_(w)), and wettability index (I_(A)). The Berea rock sample used in this study is weakly hydrophilic with I_(o), I_(w), and I_(A) of 0.318, 0.032, and 0.286, respectively. Being processed by the prepared DES samples, the wettability of the Berea sandstone samples is altered to hydrophilic (0.7 > I_(A) > 0.3) by increasing I_(w) but lowering Io. Similarly, DES-surfactant solutions can also modify the wettability of the Berea sandstone samples from weakly hydrophilic to hydrophilic. However, some DES-surfactant solutions can not only increase I_(w) but also increase I_(o), suggesting that the lipophilicity of those sandstone samples will be improved by the DES-surfactant solutions. In addition, micromodel flooding tests confirm the promising performance of a DES-surfactant solution in improving oil recovery and altering wettability. Moreover, the possible mechanisms of DES and DES-surfactant solutions in altering the wettability of the Berea sandstone samples are proposed. DES samples may improve the hydrophilicity by forming hydrogen bonds between rock surface and water molecules. For DES-surfactant solutions, surfactant micelles can capture oil molecules to improve the lipophilicity of those sandstone samples.
基金supported by the China Scholarship Council(Grant No.202306440152)the CNPC Science and Technology Major Project of the Fourteenth Five-Year Plan(Grant No.2021DJ0101)+1 种基金the Science Foundation of China University of Petroleum,Beijing(Grant No.2462022YXZZ007)the National Natural Science Foundation of China(Grant No.42102145).
文摘As the main factor influencing the flow and preservation of underground fluids,wettability has a profound impact on CO_(2)sequestration(CS).However,the influencing factors and internal interaction mechanisms of shale kerogen wettability remain unclear.In this study,we used molecular dynamics to simulate the influence of temperature,pressure,and salinity on wettability.Furthermore,the results were validated through various methods such as mean square displacement,interaction energy,electrostatic potential energy,hydrogen bonding,van der Waals forces,and electrostatic forces,thereby confirming the reliability of our findings.As temperature increases,water wettability on the surface of kerogen increases.At CO_(2)pressures of 10 and 20 MPa,as the temperature increases,the kerogen wettability changes from CO_(2)wetting to neutral wetting.As the CO_(2)pressure increases,the water wettability on the surface of kerogen weakens.When the pressure is below 7.375 MPa and the temperature is 298 or 313 K,kerogen undergoes a wettability reversal from neutral wetting to CO_(2)wetting.As salinity increases,water wettability weakens.Divalent cations(Mg2+and Ca2+)have a greater impact on wettability than monovalent cations(Na^(+)).Water preferentially adsorbs on N atom positions in kerogen.CO_(2)is more likely to form hydrogen bonds and adsorb on the surface of kerogen than H_(2)O.As the temperature increases,the number of hydrogen bonds between H_(2)O and kerogen gradually increases,while the increase in pressure reduces the number of hydrogen bonds.Although high pressure helps to increase an amount of CS,it increases the permeability of a cap rock,which is not conducive to CS.Therefore,when determining CO_(2)pressure,not only a storage amount but also the storage safety should be considered.This research method and results help optimize the design of CS technology,and have important significance for achieving sustainable development.
基金supported by the Beijing Municipal Natural Science Foundation(1242025)。
文摘Wettability has complex effects on the physical properties of reservoir rocks.The wettability of rocks should be characterized accurately to explore and develop oil and gas.Researchers have studied the rock wettability by dielectric spectra which contained abundant information.To study the rock wettability from dielectric dispersion,four rock samples with different wettabilities were used to design an experimental measurement flow.The relative dielectric permittivity in the frequency range of 100 Hz-10MHz and nuclear magnetic resonance T_(2)spectra of the samples were obtained.Subsequently,the wettabilities of the rocks were verified by the T_(2)spectra.The dielectric dispersions of the samples under different conditions were analyzed.Furthermore,the simulated-annealing(SA)algorithm was used to invert the wettability and related parameters of the rocks by a dielectric dispersion model.The results indicated that the dielectric permittivity of lipophilic rocks is lower than that of hydrophilic rocks,and that the dielectric permittivity of hydrophilic rocks decreases faster as the frequency increases.The dielectric permittivity in the high-frequency band is associated with the water content.The rock wettability parameters obtained via inversion agreed well with the T_(2)spectra,and the saturation index of the rocks.The errors between the rock permittivity calculated by the inverted parameters and the experimentally measured values were minor,indicating that rock wettability could be accurately characterized using dielectric dispersion data.
基金supported by the National Natural Science Foun-dation of China(Grant No.52176077).
文摘Bubble nucleation plays a crucial role in boiling heat transfer and other applications.Traditional experiments struggle to capture its microscopic mechanisms,making molecular dynamics simulations a powerful tool for such studies.This work uses molecular dynamics simulations to investigate bubble nucleation of water on copper surfaces with sinusoidal groove roughness under varying heat flux and surface wettability.Results show that at the same wettability,higher heat flux leads to higher surface temperatures after the same heating time,promoting bubble nucleation,growth,and departure.Moreover,under constant heat flux,stronger surface hydrophilicity enhances heat transfer from the solid to the liquid,further accelerating the nucleation.This study provides valuable insights into the mechanism of bubble nucleation and offers theoretical guidance for enhancing heat transfer.
基金supported by the National Natural Science Foundation of China(No.12172029)the open Resarch Project of Key Laboratory of Icing and Anti/De-icing of CARDC(No.IADL 20230101)。
文摘The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequently,low-energy anti/de-icing methods based on superhydrophobic surfaces have attracted widespread attention.Previous studies have demonstrated that for stationary components,superhydrophobic surfaces can significantly reduce anti-icing energy consumption by altering the flow behavior of runback water.However,for rotating inlet components of aero-engines,the effectiveness of superhydrophobic surfaces and the influence of surface wettability on the evolution of runback water flow remain unclear due to the effects of centrifugal and Coriolis forces.This study establishes a 3D liquid water flow simulation model using the volume of fluid(VOF)method to investigate the effects of rotational speed,airflow velocity,and surface wettability on the runback water flow behavior over the rotating spinner under dynamic rotation conditions.The results show that the rotational effects and surface wettability mutually reinforce one another.Specifically,increasing the rotational speed and contact angle can both enhance the flow velocity of liquid water and accelerate the breakup and rupture of liquid film,leading to the formation of rivulets,droplets,and subsequent detachment from the surface.A theoretical model based on force balance is proposed to describe the evolution of runback water flow,and the analysis reveals that as the rotational speed and contact angle increase,the water film is more likely to break up to form rivulets and beads,and the critical radius for droplet detachment from the surface decreases,making it easier removal from the surface.
基金support by Beijing Natural Science Foundation(3194046)BUCEA Post Graduate Innovation Project.
文摘The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes(PHPs)under three modified surfaces(superhydrophilic evaporation section paired with superhydrophilic,superhydrophobic,and hybrid condensation section).The Volume of Fluid(VOF)model was utilized to capture the phase-change process within the PHPs.The study also evaluated the influence of surface wettability on fluid patterns and thermo-dynamic heat transfer performance under various heat fluxes.The results indicated that the effective nucleation and detachment of droplets are critical factors influencing the thermal performance of the PHPs.The overall heat transfer performance of the superhydrophobic surface was significantly improved at low heat flux.Under medium to high heat flux,the superhydrophilic condensation section exhibits a strong oscillation effect and leads to the thickening of the liquid film.In addition,the hybrid surface possesses the heat transfer characteristics of both superhydrophilic and superhydrophobic walls.The hybrid condensation section exhibited the lowest thermal resistance by 0.45 K/W at the heat flux of 10731 W/m^(2).The thermal resistance is reduced by 13.1%and 5.4%,respectively,compared to the superhydrophobic and superhydrophilic conditions.The proposed surface-modification method for achieving highly efficient condensation heat transfer is helpful for the design and operation of device-cooling components.
基金Fund by the Science and Technology Programme Project of Bengbu City(No.2023gx01)the Key Technologies R&D Program of CNBM(No.2021HX0809)。
文摘We presented a novel porous alumina ceramics(PACs)with superoleophilicity and superoleo-phobicity when immersed in different oil-water environments.The wettability,separation efficiency,permeation flux and reusability of the PACs for oil/water separation were investigated and characterized via extensive ex-periments.The PACs material had favourable properties including mechanical strength and chemical durability compared with fabric-based materials and organic sponge-based materials previously reported in literature for oil/water separation.It is believed that the PACs material and methodology presented in this work may provide wastewater remediation industry with a promising alternative for dealing with the catastrophic ocean oil pollu-tion and other oil contamination.
基金supported by the National Natural Science Foundation of China(Nos.21901063,U20041101)Young Talents Personnel Fund of Henan Agricultural University(No.30500604)Key Science and Technology Foundation of Henan Province(Nos.242102230178,232102310379)。
文摘Herein,an alkyne-terminated acid/base responsive amphiphilic [2]rotaxane shuttle was synthesized,and then modified onto the glass surface through “click” reaction.The XPS N 1s spectrum and contactangle measurement were performed to prove the successful immobilization.The amphiphilic [2]rotaxane functionalized surface presented controllable wettability responding to external acid-base stimuli.This bistable rotaxane modified material system promoted the practical application of molecular machines.
基金supported by the National Science Centre of Poland within OPUS 16 Project,no.2018/31/B/ST8/01172。
文摘The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)using the Capillary Purification(CP)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)procedure.The high-temperature tests were performed under isothermal conditions(CP:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) atmosphere.During the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate couples.Scanning and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified couples.It was found that an oxide-free Mg drop obtained by the CP procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθ<90°in<1 s),followed by fast spreading and good wetting over the Ni substrate(θ_((CP))~20°in 5 s)to form a final contact angle ofθ_(f(CP))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test temperature.However,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.
文摘Inspired by the skin structure,an asymmetric wettability tri-layer nanofiber membrane(TNM)consisting of hydrophilic inner layer loaded with lidocaine hydrochloride(LID),hydrophobic middle layer with ciprofloxacin(CIP)and hydrophobic outer layer has been created.The hydrophobic outer layer endows the TNM with waterproof function and anti-adhesion from contaminants.The hydrophobic middle layer with CIP preserves long-term inhibition of bacteria growth and the hydrophilic inner layer with LID possesses optimal waterabsorbing capacity and air permeability.The TNM dramatically elevates the water contact angles from 10°(inner layer)to 120(outer layer),indicating an asymmetric wettability,which could directionally transport wound exudate within the materials and meanwhile maintain a comfortable and moist environment to promote wound healing.Furthermore,the sequential release of LID and CIP could relieve pain rapidly and achieve antibacterial effect in the long run,respectively.In addition,the TNM shows superior biocompatibility towards L929 cells.The in vivo results show the TNM could prevent infection,accelerate epithelial regeneration and significantly accelerate wound healing.This study indicates the developed TNM with asymmetrical wettability and synergetic drug release shows great potential as a wound dressing in clinical application.
基金financial support from the National Natural Science Foundation of China(“Study of Multi-Responsive Shape Memory Polyurethane Nanocomposites Inspired by Natural Fibers”,Grant No.51673162)Startup Grant of CityU(“Laboratory of Wearable Materials for Healthcare”,Grant No.9380116).CityU PhD Scholarship.
文摘Thermoregulatory textiles,leveraging high-emissivity structural materials,have arisen as a promising candidate for personal cooling management;however,their advancement has been hindered by the underperformed water moisture transportation capacity,which impacts on their thermophysiological comfort.Herein,we designed a wettability-gradient-induced-diode(WGID)membrane achieving by MXene-engineered electrospun technology,which could facilitate heat dissipation and moisture-wicking transportation.As a result,the obtained WGID membrane could obtain a cooling temperature of 1.5℃ in the“dry”state,and 7.1℃ in the“wet”state,which was ascribed to its high emissivity of 96.40%in the MIR range,superior thermal conductivity of 0.3349 W m^(-1) K^(-1)(based on radiation-and conduction-controlled mechanisms),and unidirectional moisture transportation property.The proposed design offers an approach for meticulously engineering electrospun membranes with enhanced heat dissipation and moisture transportation,thereby paving the way for developing more efficient and comfortable thermoregulatory textiles in a high-humidity microenvironment.
文摘The production of renewable fuels through water splitting via photocatalytic hydrogen production holds significant promise.Nonetheless,the sluggish kinetics of hydrogen evolution and the inadequate water adsorption on photocatalysts present notable challenges.In this study,we have devised a straightforward hydrothermal method to synthesize Bi_(2)O_(3)(BO)derived from metal‐organic frameworks(MOFs),loaded with flower-like ZnIn_(2)S_(4)(ZIS).This approach substantially enhances water adsorption and surface catalytic reactions,resulting in a remarkable enhancement of photocatalytic activity.By employing triethanolamine(TEOA)as a sacrificial agent,the hydrogen evolution rate achieved with 15%(mass fraction)ZIS loading on BO reached an impressive value of 1610μmol∙h^(−1)∙g^(−1),marking a 6.34-fold increase compared to that observed for bare BO.Furthermore,through density functional theory(DFT)and ab initio molecular dynamics(AIMD)calculations,we have identified the reactions occurring at the ZIS/BO S-scheme heterojunction interface,including the identification of active sites for water adsorption and catalytic reactions.This study provides valuable insights into the development of high-performance composite photocatalytic materials with tailored electronic properties and wettability.
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0470201)Beijing Natural Science Foundation(No.JQ23008)the National Natural Science Foundation of China(Nos.22275203 and 22035008)。
文摘Disgusting deposits(e.g.,scale and crude oil)in daily life and industrial production are always serious problems,posing great threats to the safety and economic development.However,most of developed coatings can only conquer one part of these deposits such as superhydrophobic coatings possess antiscaling capacity but would adhere crude oil.To integrate scale resistance with oil repellence,we herein report a robust superamphiphobic(SAB)coating simultaneously reducing pollution of scale and oil for extended period of time(two weeks with over 98%reduction).Compared with single role of superhydrophobic and amphiphilic surfaces,the SAB coating can not only inhibit interfacial nucleation of scale but also reduce the adhesion of formed scale and polluted oil.The durability of the SAB coating is evaluated via mechanical tests(sandpaper abrasion,tape stripping and sand falling)and chemical corrosion(corrosive liquid immersing),revealed by sustainable high contact angles and low contact angle hysteresis of water and oil.The universality of this strategy can be further confirmed by adding different particles like kaolin,Al_(2)O_(3),and SiO_(2),resisting multiple types of scale(i.e.,CaSO_(4),BaSO_(4)and MgCO_(3))and oil(i.e.,glycerol,glycol,and mineral oil).Therefore,this study provides an ideal avenue for resisting scale and oil,which may be used for conquering the complexity of application environments(e.g.,oil production and transportation).
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDC04010100)National Key Research and Development Program of China(Grant No.2018YFC1900500)+1 种基金the Special Project for Transformation of Major Technological Achievements in Hebei Province(Grant No.19044012Z)the Science and Technology Program of Hengshui(Grant No.2020016004B).
文摘The sodium smelting of vanadium-titanium magnetite can achieve the comprehensive utilization of Fe,V,and Ti.However,the generation of alkaline slag during this process may cause damage to refractory materials.The wettability and corrosion behavior of alkaline slag on three types of refractory(MgO-C,SiC,and high alumina refractory)substrates were investigated at temperatures up to 1200℃.The effects of duration on the wettability of molten slag on SiC substrates were also investigated.Results showed that the high alumina refractory exhibited better wettability with the molten slag than the others,and thus,it is easier to be corroded.The results of scanning electron microscopy coupled with energy dispersive spectroscopy showed that MgO-C and high alumina refractory substrates were severely eroded.There was a visible and regular interfacial reaction layer between the slag and SiC refractory substrate,which was produced by the redox reaction between the metal oxides in the slag and the SiC refractory substrate.With the increase in holding time,the interface layer expands and silico-ferrite phases are generated at the interface.The redox reaction between Fe_(2)O_(3) and SiC substrate is the main reason for the corrosion.By comparing the differences in wettability and corrosion behavior between the alkaline slag from sodium smelting of vanadium-titanium magnetite and MgO-C,SiC and high alumina refractories,it is concluded that SiC refractory has good corrosion resistance to the slag.Iron oxides in the slag accelerate the oxidation rate of SiC refractory.
基金the support of the China Manned Space Engineering(YYMT1201-EXP08)。
文摘The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of the wettability and interface characteristics between the reinforcing phase and the bulk metallic glasses(BMGs).This work optimized the composition of Zr-based BMGs through microalloying methods,resulting in a new set of Zr-based BMGs with excellent glass-forming ability.Wetting experiments between the Zr-based BMGs melts and W substrates were conducted using the traditional sessile drop method,and the interfaces were characterized utilizing a scanning electron microscope(SEM)equipped with energy dispersive X-ray spectroscopy(EDS).The work demonstrates that the microalloying method substantially enhances the wettability of the Zr-based BMGs melt.Additionally,the incorporation of Nb element impedes the formation of W-Zr phases,but the introduction of Nb element does not alter the extent of interdiffusion between the constituent elements of the amorphous matrix and W element,indicating that the influence of Nb element on the diffusion of individual elements is minute.
基金Supported by the Original Exploration Project of National Natural Science Foundation of China(5215000105)Young Teachers Fund for Higher Education Institutions of Huo Yingdong Education Foundation(171043)。
文摘A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2spectrum,and the time-varying law of simulated oil viscosity in porous media is quantitatively characterized by nuclear magnetic resonance(NMR)experiments of high multiple waterflooding.A new NMR wettability index formula is derived based on NMR relaxation theory to quantitatively characterize the time-varying law of rock wettability during waterflooding combined with high-multiple waterflooding experiment in sandstone cores.The remaining oil viscosity in the core is positively correlated with the displacing water multiple.The remaining oil viscosity increases rapidly when the displacing water multiple is low,and increases slowly when the displacing water multiple is high.The variation of remaining oil viscosity is related to the reservoir heterogeneity.The stronger the reservoir homogeneity,the higher the content of heavy components in the remaining oil and the higher the viscosity.The reservoir wettability changes after water injection:the oil-wet reservoir changes into water-wet reservoir,while the water-wet reservoir becomes more hydrophilic;the degree of change enhances with the increase of displacing water multiple.There is a high correlation between the time-varying oil viscosity and the time-varying wettability,and the change of oil viscosity cannot be ignored.The NMR wettability index calculated by considering the change of oil viscosity is more consistent with the tested Amott(spontaneous imbibition)wettability index,which agrees more with the time-varying law of reservoir wettability.
基金supported by the Guangzhou Science and Technology Plan(No.202102020219)National Natural Science Foundation of China(No.51908565)High-level talent research startup project of Chongqing Technology and Business University(No.2356007)。
文摘Membrane-based separation is a promising technology to eliminate water impurities from the oil phase.However,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in oil.Herein we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil(W/O)emulsion.Silanes with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface wettabilities.While all the modified membranes exhibited excellent separation of the W/O without Span 80(surfactant),the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/O.The presence of Span 80 reduced the interfacial tension of water droplets,making them easier to deform and penetrate the modified membrane with the lowest surface energy.It reveals that engineering proper surface wettability is the key to separating the oil and water phases.Besides,the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.
基金supported by National Natural Science Foundation of China(Grant No.42172159)Science Foundation of China University of Petroleum,Beijing(Grant No.2462023XKBH002).
文摘Multiphase flow in low permeability porous media is involved in numerous energy and environmental applications.However,a complete description of this process is challenging due to the limited modeling scale and the effects of complex pore structures and wettability.To address this issue,based on the digital rock of low permeability sandstone,a direct numerical simulation is performed considering the interphase drag and boundary slip to clarify the microscopic water-oil displacement process.In addition,a dual-porosity pore network model(PNM)is constructed to obtain the water-oil relative permeability of the sample.The displacement efficiency as a recovery process is assessed under different wetting and pore structure properties.Results show that microscopic displacement mechanisms explain the corresponding macroscopic relative permeability.The injected water breaks through the outlet earlier with a large mass flow,while thick oil films exist in rough hydrophobic surfaces and poorly connected pores.The variation of water-oil relative permeability is significant,and residual oil saturation is high in the oil-wet system.The flooding is extensive,and the residual oil is trapped in complex pore networks for hydrophilic pore surfaces;thus,water relative permeability is lower in the water-wet system.While the displacement efficiency is the worst in mixed-wetting systems for poor water connectivity.Microporosity negatively correlates with invading oil volume fraction due to strong capillary resistance,and a large microporosity corresponds to low residual oil saturation.This work provides insights into the water-oil flow from different modeling perspectives and helps to optimize the development plan for enhanced recovery.
基金funded by the National Key R&D Program of China(No.2018YFA0702400).
文摘Adhesion of oil at rock surface plays an important role in the liberation of oil from micro-/nano-pores,especially for heavy oil that has extremely high viscosity.Although molecular dynamics simulation is widely used to study the interfacial interaction for some specific oil-water-rock systems,experimental measurements provide more realistic and reliable evidence.In this work,we propose a dynamic wettability characterization method to indirectly measure resistant forces at oil-surfactant-rock interfaces,including frictional force,wettability hysteresis force,and viscous force,which are parallel with the oil-solid interface.The adhesive force,which is normal to the oil-solid interface is calculated through measurement of work of adhesion.The results show that work of adhesion instead of contact angle can better describe the adhesion of oil at solid surface.The effect of surfactant concentration on work of adhesion is different for water-wet and oil-wet surfaces.Moreover,average viscous forces are calculated through force analysis on oil drops moving along solid surface in different surfactant environments.It is found that viscous force has a magnitude comparable to the frictional force during the movement,while the wettability hysteresis force is negligible.On the other hand,the adhesive force calculated from the work of adhesion is also comparable to the viscous force.Therefore,both the resistant forces parallel with and normal to the oil-solid interface should be minimized for the liberation of oil from rock surface.This work proposes a simple method to evaluate the wetting capability of different surfactants and measure the adhesive force between heavy oil and rock surfaces indirectly,which provides insight into the adhesion of heavy oil at rock surface and would be valuable for the development of surfactant-based oil recovery methods.
