Wettability Modification Research Articles

Smart Water for Enhanced Oil Recovery by Nano-Filtration

Chemistry of injected water can modify the wettability behaviour of carbonate reservoirs. Wettability modification towards more water-wet reservoir rocks results in increased oil production. Smart water production by selective ionic water content is a major developing area in current enhanced oil recovery (EOR). Technical limitations for smart water production for EOR using seawater as feed for membranes are described in this paper. Desired characteristics of smart water for injection into carbonate reservoirs are low Na+ and Cl- and high divalent ion concentrations. Wettability alteration by smart water occurs due to symbiotic behaviour of Ca2+, SO4 2- and Mg2+ ions and the carboxylic material of the reservoir rock surface. Nano-filtration (NF) and Reverse Osmosis (RO) membranes were used for ion separation experiments. Retentate from NF contains the main constituents of smart water. Membrane performance was evaluated in terms of rejection under varying feed compositions and pressures. An analysis of general approaches for water injection processes from seawater is discussed. This paper delivers an economic framework for evaluation of the water injection process by including major technical and economical elements. Main criteria considered in this research were how to decrease monovalent ion rejection. This was achieved by increasing divalent ion concentration by spiking feed water with selected chemicals. Results showed that a decrease in retention of monovalent ions was achieved by increasing multivalent ion concentration in the feed. A challenge of smart water production is the high dissolved solids content (TDS) in retentate from NF. Three options to dilute the retentate were evaluated; i.e., combinations of NF and RO, MSFD and fresh water. The most feasible process is a combination of NF and RO, with an energy consumption of 3.8 kWh/m3.

Hydrothermal and plasma treatments drastically reduce bacterial adhesion to Ti-based materials used in medicine

Event Abstract Back to Event Hydrothermal and plasma treatments drastically reduce bacterial adhesion to Ti-based materials used in medicine Martina Lorenzetti1, Špela Koželj2, Iztok Dogša2, Ita Junkar3, Mitjan Kalin4, David Stopar2 and Saša Novak1, 5 1 Jožef Stefan Institute, Department for Nanostructured Materials, Slovenia 2 University of Ljubljana, Biotechnical Faculty, Slovenia 3 Jožef Stefan Institute, Department of Surface Engineering and Optoelectronics, Slovenia 4 University of Ljubljana, Faculty of Mechanical Engineering, Slovenia 5 Jožef Stefan International Postgraduate School, Slovenia Introduction: Even though titanium and its alloys are generally considered good materials for load-bearing orthopaedic implants, microbial pre-surgical infections and biofilm formation pose a serious threat, known as “prosthetic implant infections”[1]. The infection contributes to a number of implant failures and revisions and it will become even more problematic in the near future, when a massive increase of arthroplasties is expected. In this study we focused on the production of bacterial anti-adherent coatings by applying hydrothermal treatment (HT) and/or highly reactive oxygen plasma (PL) to medical-grade titanium substrates. The microbial interaction at the biointerface was tested as the fraction of adhered bacteria to the surface. Materials and Methods: Nanocrystalline TiO2-anatase coatings were synthesised on titanium discs by HT in the presence of Ti-isopropoxide, as described previously[2]. The non-treated titanium was used as control. In addition, the samples were treated by highly reactive oxygen plasma. The samples were characterised in terms of crystal morphology (electron microscopy), wettability (sessile drop contact angle), topography and roughness (optical interferometer), surface charge (streaming potential), and chemical composition (X-ray photoelectron spectroscopy). The adhesion of a green fluorescent protein-tagged Escherichia coli bacterium on the different surfaces was tested after 1h of incubation. The fraction of strongly adhered bacteria was determined by fluorescence microscopy. Results and Discussion: The HT and PL treatments shape the surface topography, and modify the surface hydrophilicity as well as surface charge, in comparison to the pristine titanium substrate. Moreover, both HT and PL surface modifications affect the surface chemistry of titanium, as demonstrated by the increased surface oxygen content. The bacterial adhesion tests showed that after 1 h of incubation approximately 15 % of seeded bacteria strongly adhere on the bare, non-treated titanium surface. As given in Figure 1, the HT-coating significantly decreased the bacterial adhesion by an order of magnitude (2.6 %). Similar decrease was observed with the plasma treatment applied on bare titanium (2.9 %). However, when the two surface treatments were combined, a two-orders of magnitude decrease in bacterial adhesion was observed (0.25 %). The results suggest that the modification of surface topography, wettability and surface chemistry by HT and PL treatments led to a beneficial combination of surface properties which dramatically reduced the bacterial adhesion to titanium surfaces. Figure 1. Fraction of bacteria adhered to different surfaces. Ti, titanium substrate; Ti Pl, plasma-treated titanium substrate; HT, hydrothermally coated titanium substrate; HT+PL, hydrothermally coated and plasma-treated titanium substrate. Conclusion: This study demonstrates how the fine tuning of TiO2 surface properties by hydrothermal and plasma treatments significantly diminish bacterial adhesion and, consequently, prevents the biofilm formation. Therefore it is expected that the combination of the two treatments may contribute to the reduction of pre-surgical prosthetic implant infections. Authors wish to thank the Slovenian Research Agency for the financial support (P2-0084, P4-0116).

Topographical and Physicochemical Contrast in Photopatterned SU-8 Films for Microfabrication of Multilayer Structures

During SU-8 standard photolithography process, a patterned topography is formed with a characteristic height profile produced by the different shrinkage of the UV exposed and masked regions. We study the change of wettability, film solubility, and topographic modifications on SU-8 films of different thicknesses and show its relevance in the formation of spinning-flow arrays on top layers made from positive photoresists. Also, considerable contrast in film solubility and surface energy as observed from contact angle measurements is produced. Interface diffusion of the photoresists was also observed and followed by Rutherford Back Scattering. We discuss the derivations of the mentioned effects concerning the limitations to multilayered microfabrication processes and possibilities to take advantage of the surface profiles obtained.

An Experimental Investigation into the Impact of Sulfate Ions in Smart Water to Improve Oil Recovery in Carbonate Reservoirs

Carbonate reservoirs are considered to be in the range of mixed to oil wetting state. Their present wetting state seems unfavorable to recover more oil via conventional waterflooding especially as the water cut increases with huge residual oil saturation. In recent years, studies have shown that tuning the injected brine chemistry can help decrease the oil-wetness, resulting in additional oil recovery and reduction in residual oil saturation. Thus, rock wettability is being dictated by the surface chemistry associated with the water-film stability between crude oil and the rock surface. This study presents series of experiments conducted on Middle Eastern carbonate core plugs at high pressure and high temperature in order to determine the impact of sulfate ions in smart brine on oil recovery. Each experiment was initially conducted using the formation brine, and subsequently, various versions of seawater with varying sulfate concentrations were used. Coreflooding experiments showed an additional recovery of about 7–9 % oil originally in core when sulfate concentration was increased while none when decreased. Decrease in rock oil-wetness was observed to be responsible for the improved recovery as demonstrated by the contact angle analysis. Similar trend was observed with the zeta potential analysis which further proved that the magnitude of surface charge alteration contributes immensely to wettability modification toward more water-wetness.

Microfluidic Investigation of Nanoparticles’ Role in Mobilizing Trapped Oil Droplets in Porous Media

The flow of multiple fluid phases in porous media often results in trapped droplets of the nonwetting phase. Recent experimental and theoretical studies have suggested that nanoparticle aqueous dispersions may be effective at mobilizing trapped droplets of nonwetting fluid (oil) in porous media. Hypotheses to explain the observation include the nanoparticles' modification of solid wettability, droplet stabilization, and changes in interfacial tension and interface rheology. However, because it is difficult to observe droplet behavior on the pore scale, how those factors contribute to oil droplet mobilization has not been fully understood. In this work, we investigated the nanoparticles' role in nanoparticle-based improved recovery of the nonwetting phase through the direct observation of the mobilization of trapped oil droplets in microfluidic structures that mimic pore-throat geometries. A microfluidic platform was constructed for this study, on which different displacing liquids including aqueous surfactant solutions and nanoparticle suspensions were tested. We found that the nanoparticle concentration is positively related to the oil mobilization efficiency. An approximate mathematical model for calculating the maximum size of an oil droplet trapped in a pore-throat geometry for a fixed flow rate matches the experiment result for displacing liquid with no nanoparticles. The model still holds when the nanoparticle suspension is a displacing liquid. We concluded that nanoparticles mobilize oil in these geometries in a mechanism similar to that for surfactants, which is an increase in capillary number rather than an effect of other fluidic or interfacial properties such as the dynamics adsorption of nanoparticle or dilational rheology of a nanoparticle-adsorbed interface.

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75°. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15°, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer’s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103°. The XPS results indicate ArF laser induced formation of Si–(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment.

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75°. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm(2), respectively, has decreased the CA to near 15°, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer's surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm(2) and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103°. The XPS results indicate ArF laser induced formation of Si-(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

A novel chemical additive for in-situ recovery of heavy oil using waterflooding process

Abstract Chemical-assisted waterflooding is injection of specialty chemical(s) along with water to enhance the productivity through a series of mechanisms. There are several mechanisms responsible for increased ultimate recovery of such a process compared to the traditional waterflooding process including in-situ emulsification of oil, conformance control and treatment of adverse mobility ratio, reduction of Interfacial Tension (IFT) between the in-situ oil and the injecting phase, and wettability modification to facilitate recovery of oil by enhanced relative permeability values. Although chemical-assisted waterflooding has been applied since the early 20th century, it has not been until recently that applicability of this process has been tested for recovery of heavy oil using preliminary macro-scale as well as pore-scale studies. A new chemical technology (i.e. IPC Technology as referred in this paper) has been developed. A proprietary mixture of surfactants is used in several techniques associated with surface extraction as well as in-situ recovery of heavy oil and bitumen. This formulation of solvents and surfactants is reusable, low foaming, non-flammable, not acutely toxic and non-carcinogenic. A systematic study, based on a series of coreflood tests, was designed and conducted to assess efficacy of IPC in the ultimate recovery of different types of oils by use of IPC-assisted waterflooding. Effects of IPC on IFT between oil and IPC solutions at different brine salinities/hardnesses and IPC concentrations were determined. Compatibility of IPC with different brine hardnesses and salinities was determined. IPC technology was particularly effective in recovering heavy oil. The performance of IPC as an additive during waterflood at elevated temperature for recovery of heavy oil was also investigated. For this particular purpose, thermal stability tests were conducted to determine the threshold temperature below which the formulation is thermally stable. When production performance of IPC-assisted waterflood was compared with alkali flooding and a commercial surfactant, IPC gave superior ultimate recovery.

Turning bubbles on and off during boiling using charged surfactants.

Boiling—a process that has powered industries since the steam age—is governed by bubble formation. State-of-the-art boiling surfaces often increase bubble nucleation via roughness and/or wettability modification to increase performance. However, without active in situ control of bubbles, temperature or steam generation cannot be adjusted for a given heat input. Here we report the ability to turn bubbles ‘on and off' independent of heat input during boiling both temporally and spatially via molecular manipulation of the boiling surface. As a result, we can rapidly and reversibly alter heat transfer performance up to an order of magnitude. Our experiments show that this active control is achieved by electrostatically adsorbing and desorbing charged surfactants to alter the wettability of the surface, thereby affecting nucleation. This approach can improve performance and flexibility in existing boiling technologies as well as enable emerging or unprecedented energy applications.

Surface Wettability Modification of Cyclic Olefin Polymer by Direct Femtosecond Laser Irradiation.

The effect of laser irradiation on surface wettability of cyclic olefin polymer (COP) was investigated. Under different laser parameters, a superhydrophilic or a superhydrophobic COP surface with a water contact angle (WCA) of almost 0° or 163°, respectively, could be achieved by direct femtosecond laser irradiation. The laser power deposition rate (PDR) was found to be a key factor on the wettability of the laser-treated COP surface. The surface roughness and surface chemistry of the laser-irradiated samples were characterized by surface profilometer and X-ray photoelectron spectroscopy, respectively; they were found to be responsible for the changes of the laser-induced surface wettability. The mechanisms involved in the laser surface wettability modification process were discussed.

Wettability modification of human tooth surface by water and UV and electron-beam radiation.

The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions.

Analysis on Capillary Pressure Curves by Wettability Modification through Surfactants

Wettability of a reservoir rock is closely related to capillary pressure curves. The status of wettability is an important factor for oil recovery, can be clearly seen through the variations in capillary pressure curves. The aim is to analyze the changes in capillary pressure curves and saturations by altering wettability. An oil wet core sample was tested to alter wettability. During alteration process it is difficult to analyze the status of wettability. Surfactants were applied to modify wettability. Additionally, parameters like connate water saturation, spontaneous oil and water saturations, residual oil saturation and type of wettability can be analyzed. The concentration of surfactants was selected by conductivity test. The changes in saturations with variations in capillary pressure curves were stated.

Modification of wettability of stainless steel by picosecond laser surface microstructuring

We report on the modification of the wettability of stainless steel by picosecond laser surface microstructuring in this paper. Compared with traditional methods, picosecond laser-induced surface modification provides a fast and facile method for surface modification without chemical damage and environmental pollution. As a result of treatment by 100 ps laser pulses, microstructures are fabricated on the stainless steel sample surface, contributing to the increase of the contact angle from 88° to 105°, which realizes a transformation from hydrophilicity to hydrophobicity. The morphological features of fabricated microstructures are characterized by scanning electron microscopy and optical microscopy.

Effect of Surface Property on Transfer-Print of Au Thin-Film to Micro-Structured Substrate

This present study describes a novel micro-fabrication technique using transfer-print of thin-film for micro-mechanical structure. Some thin-films of Au have been transferred from a stamp onto pre-structured micro-ridges of polymer substrate. These thin-films successfully form into an array of fixed micro-beams as a mechanical structure. The fabricated micro-beams typically have a thickness of less than 100 nm and a tens micro-meter long. This present paper also reports an investigation about effects of stamp surface properties. A modification of stamp surface wettability and roughness improves adhesive force (releasability) of thin-film to provide flat micro-beam without undesired deformations. Hydrophobic stamp with micro-roughness results in an increase of production yield of micro-beams to reach more than 90%. Simple mechanical test shows that the fabricated micro-beam is transversely tensioned by the supporting micro-ridges of substrate. It is clarified that the proposed process can be applied to fabricate micro/nano-mechanical elements.

Wettability modification by fluoride and its application in aqueous phase trapping damage removal in tight sandstone reservoirs

Abstract External fluid invading into reservoir could induce formation damage in form of phase trapping in tight sandstone reservoirs (in-situ permeability

Wettability modification of graphene oxide by removal of carboxyl functional groups using non-thermal effects of microwave

We study the non-thermal effects of microwave on the wettability of graphene oxide. It is shown that removal of carboxyl compound by using the non-thermal microwave effects decrease the wettability of graphene oxide. X-ray photoelectron spectroscopy (C1s and O1s peaks) and Fourier transform infrared spectroscopy show that carboxyl compound decreases dramatically due to microwave irradiation while other functional groups were gradually reduced. Consequently, after 20min microwave irradiation, carboxyl functional groups are removed. Wettability tests of carboxyl-reduced graphene oxide show that water uptake capability decreases to half and contact angle of water droplets increases from ~29.7° to ~69.9°.

Wettability Modification and Its Impact on Oil Recovery

Prior to the flooding tests, interfacial tension measurements between the oil and brine samples were performed for different type of oils and 5,000-ppm surfactant solution. For the case of the nonionic surfactant-black oil system, the system was best described as a case of mixed wettability. For the anionic surfactant-black oil system, there was an increase in enhanced oil recovery as surfactant concentration increased. For the anionic surfactant-tetradecane system, again the presence of emulsion for concentrations greater than 500 ppm limited the analysis. Nevertheless, for concentrations of 1,500 ppm or less the application was efficient, resulting in enhanced oil recovery of approximately 5%.

Multifunctional Properties of Zwitterionic Liquids. Application in Enhanced Oil Recovery and Asphaltene Aggregation Phenomena

In this experimental study is investigated the performance of a new class of zwitterionic liquids (ZL) as multifunctional agents with asphaltene inhibition-dispersion activity as well as rock wettability and relative permeability modification properties to increase oil recovery factor. Asphaltenes isolated from two crude oil samples (light and heavy) and a crude oil sediment were used to evaluate the inhibition-dispersion performance of ZL, whereas two different rock samples were used to carry out the core flooding tests in order to evaluate the influence of the porous media properties on the performance of the ZL product in recovery factor enhancement. Results demonstrated that ZL can be used to control aggregation and deposition of asphaltenes as well as to modify rock wettability in order to increase the oil recovery factor. Finally, in order to explain how the chemical product enhances oil recovery, a mechanism involving oil production and rock wettability alteration is discussed.

Interface engineering of a CoO(x)/Ta3N5 photocatalyst for unprecedented water oxidation performance under visible-light-irradiation.

Cocatalysts have been extensively used to promote water oxidation efficiency in solar-to-chemical energy conversion, but the influence of interface compatibility between semiconductor and cocatalyst has been rarely addressed. Here we demonstrate a feasible strategy of interface wettability modification to enhance water oxidation efficiency of the state-of-the-art CoO(x)/Ta3N5 system. When the hydrophobic feature of a Ta3N5 semiconductor was modulated to a hydrophilic one by in situ or ex situ surface coating with a magnesia nanolayer (2-5 nm), the interfacial contact between the hydrophilic CoO(x) cocatalyst and the modified hydrophilic Ta3N5 semiconductor was greatly improved. Consequently, the visible-light-driven photocatalytic oxygen evolution rate of the resulting CoO(x)/MgO(in)-Ta3N5 photocatalyst is ca. 23 times that of the pristine Ta3N5 sample, with a new record (11.3%) of apparent quantum efficiency (AQE) under 500-600 nm illumination.

Interface Engineering of a CoOx/Ta3N5 Photocatalyst for Unprecedented Water Oxidation Performance under Visible‐Light‐Irradiation

AbstractCocatalysts have been extensively used to promote water oxidation efficiency in solar‐to‐chemical energy conversion, but the influence of interface compatibility between semiconductor and cocatalyst has been rarely addressed. Here we demonstrate a feasible strategy of interface wettability modification to enhance water oxidation efficiency of the state‐of‐the‐art CoOx/Ta3N5 system. When the hydrophobic feature of a Ta3N5 semiconductor was modulated to a hydrophilic one by in situ or ex situ surface coating with a magnesia nanolayer (2–5 nm), the interfacial contact between the hydrophilic CoOx cocatalyst and the modified hydrophilic Ta3N5 semiconductor was greatly improved. Consequently, the visible‐light‐driven photocatalytic oxygen evolution rate of the resulting CoOx/MgO(in)–Ta3N5 photocatalyst is ca. 23 times that of the pristine Ta3N5 sample, with a new record (11.3 %) of apparent quantum efficiency (AQE) under 500–600 nm illumination.