Dynamic Wilhelmy plate technique

Formation Wettability Studies that Incorporate the Dynamic Wilhelmy Plate Technique... 

The sessile drop method has several drawbacks. Several days elapse between each displacement, and total test times exceeding one month are not uncommon. It can be difficult to determine that the interface has actually advanced across the face of the crystal. Displacement frequency and distance are variable and dependent upon the operator. Tests are conducted on pure mineral surfaces, usually quartz, which does not adequately model the heterogeneous rock surfaces in reservoirs. There is a need for a simple technique that gives reproducible data and can be used to characterize various mineral surfaces. The dynamic Wilhelmy plate technique has such a potential. This paper discusses the dynamic Wilhelmy plate apparatus used to study wetting properties of liquid/liquid/solid systems important to the oil industry. 

The computer interface system lends itself well to the determination of interfacial tension and contact angles using Equation 3 and the technique described by Pike and Thakkar for Wilhelmy plate type experiments (20). Contact angles for crude oil/brine systems using the dynamic Wilhelmy plate technique have been determined by this technique and all three of the wetting cycles described above have been observed in various crude oil/brine systems (21) (Teeters, D. Wilson, J. F. Andersen, M. A. Thomas, D. C. J. Colloid Interface Sci., 1988, 126, in press). The dynamic Wilhelmy plate device also addresses other aspects of wetting behavior pertinent to petroleum reservoirs. 

This same technique should be helpful in understanding wetting properties important in the oil industry since wetting is very dependent on mineral surface energies. The use of contact angle hysteresis information may allow a better understanding of the effects of surface heterogeneities of natural mineral samples. The dynamic Wilhelmy plate technique is ideally suited for such experiments ... 

The electron probe microanalysis (EPMA) spectra were obtained with Shi-madzu EMX-SM (Shimadzu, Co. Kyoto, Japan). The EPMA was operated under an excitation voltage of 15 kV and a sample current of 0.003 mA. A spectrometer ESCA 1000 (Shimadzu Co., Kyoto, Japan) was employed to carry out X-ray photoelectron spectroscopy (XPS) [40-42]. The dynamic contact angle of the PASs was measured using the dynamic Wilhelmy plate technique [43] by means of a Orientic DCA-20 (Orientic Co., Tokyo, Japan). 

Steady State Expansion Measurements. The dynamic surface tension in steady state expansion was determined using a modified Langmuir trough equipped with six barriers fixed to an endless belt which were moved caterpillar-wise one after another over the liquid surface.10,24 Surface tension was determined using the Wilhelmy plate technique. Measurements were performed going from the highest to the lowest expansion rate. 

Contact Angle Measurement. Dynamic contact angle measurement was performed on the dried hydrogels at 25°C by the Wilhelmy plate technique using equipment manufactured by Shimadzu Inc. (Automated System for Dynamic Contact Angle Measurement, ST-IS type) Water used for the measurement was purified by de-ionization after double distillation. Five measurements on different parts of the film were averaged. The movement rate of the water vessel into which the gel specimen was immersed was kept at 0,3 mm sec , ... 

As soon as the coated slides were removed from the oven and cooled to room temperature, dynamic contact angles were measured by the Wilhelmy plate technique [21], We obtained the wetting curve with an electrobalance (Cahn Model... 

Dynamic contact angle Wilhelmy plate technique Banana stem and bunch 26... 

The dynamic process of adsorption of emulsifiers and the equilibrium state of the interfacial film can be measured by the change in interfacial tension as a function of time. Dynamic interfacial tension techniques exist that measure without disturbing the interface. Various such techniques to measure interfacial tension have been reported in the literature (Addison and Hutchinson, 1949 Padday and Russel, 1960). The Wilhelmy plate technique is preferred over other techniques because the values obtained are more accurate than those obtained using other techniques such as the capillary rise or du Nouy ring methods (Padday and Russel, 1960). In the latter two methods, the long equilibration time (3-60 hours) and difficulties in accurately positioning the... 

Dynamic surface tension has also been measured by quasielastic light scattering (QELS) from interfacial capillary waves [30]. It was shown that QELS gives the same result for the surface tension as the traditional Wilhelmy plate method down to the molecular area of 70 A. QELS has recently utilized in the study of adsorption dynamics of phospholipids on water-1,2-DCE, water-nitrobenzene and water-tetrachloromethane interfaces [31]. This technique is still in its infancy in liquid-liquid systems and its true power is to be shown in the near future. 

The Wilhelmy hanging plate method (13) has been used for many years to measure interfacial and surface tensions, but with the advent of computer data collection and computer control of dynamic test conditions, its utility has been greatly increased. The dynamic version of the Wilhelmy plate device, in which the liquid phases are in motion relative to a solid phase, has been used in several surface chemistry studies not directly related to the oil industry (14- 16). Fleureau and Dupeyrat (17) have used this technique to study the effects of an electric field on the formation of surfactants at oil/water/rock interfaces. The work presented here is concerned with reservoir wettability. 

This unit will introduce two fundamental protocols—the Wilhelmy plate method (see Basic Protocol 1 and Alternate Protocol 1) and the du Noiiy ring method (see Alternate Protocol 2)—that can be used to determine static interfacial tension (Dukhin et al., 1995). Since the two methods use the same experimental setup, they will be discussed together. Two advanced protocols that have the capability to determine dynamic interfacial tension—the drop volume technique (see Basic Protocol 2) and the drop shape method (see Alternate Protocol 3)—will also be presented. The basic principles of each of these techniques will be briefly outlined in the Background Information. Critical Parameters as well as Time Considerations for the different tests will be discussed. References and Internet Resources are listed to provide a more in-depth understanding of each of these techniques and allow the reader to contact commercial vendors to obtain information about costs and availability of surface science instrumentation. 

Provides measuring techniques of contact angle, surface tension, interfacial tension, and bubble pressure. Suitable methods for both static and dynamic inteifacial tension of liquids include du Nous ring, Wilhelmy plate, spinning drop, pendant drop, bubble pressure, and drop volume techniques. Methods for solids include sessile drop, dynamic Wilhelmy, single fiber, and powder contact angle techniques. 

It is very well known that the nature of the monolayer partially depends on the strength of interfacial interactions with substrate molecules and that of polymer in-tersegmental interactions. And it is normal to expect that the viscoelastic properties of polymer monolayer are also dependent on these factors. The static and dynamic properties of several different polymer monolayers at the air - water interface have been examined with the surface quasi-elastic Light Scattering technique combined with the static Wilhelmy plate method [101]. 

The surface tension measurement techniques can be divided into the following three categories (i) Force Methods, which include the truly static methods of the capillary rise and Wilhelmy plate methods, as well as the dynamic detachment methods of the Du Nouy ring and drop weight, (ii) Shape Methods, which include the pendant or sessile drop or bubble, as well as the spinning drop methods, and (iii) Pressure Methods, which are represented by the maximum bubble pressure method. These techniques are summarized in the following sections of this chapter. 

The method is based on Wilhelmy s plate technique for measuring dynamic contact angles. The technique involves the measurement of force as a plate is (automatically) immersed in and then emersed from a liquid at a constant rate. The forces (weight) can be plotted as a function of the immersion depth and, from this, contact angles calculated (Figures 1.26a and b). The Wilhemy s plate technique has been commercialized with computer automation and data-handling features, which has improved its utility considerably. 

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