Screen viscometer

Screen Factor. Screen Factor, the ratio of passage time of a solution to that of a solvent in a screen viscometer(45),... 

FIGURE 5.33 Schematic of screen viscometer apparatus for measuring screen factor. 

Experimental set-up and procedure Macroemulsions were produced by constant sonication for a period of about forty-five minutes in a thermostated bath at desired temperatures. Kinematic viscosity and specific conductance data of emulsions were obtained using standard Cannon-Fenske viscometer and conductivity meter, respectively. Bulk density and Screen factors of emulsions and equilibrated phases were determined by standard specific gravity bottles and screen viscometer, respectively. The interfacial tension values of oil/aqueous systems were measured by spinning drop technique. The details of measurement procedures are described elsewhere (4,5). 

Screen factor is a measure of the visco-elastic properties of polymer solutions and how they behave in porous media [50,51]. Figure 6 shows the screen factor monotonically increases with polymer concentration. According to Unsal, the shear rate encountered in a screen viscometer is nearly 1,000 s [52]. At such high shear rates, shear viscosities obtained by extrapolating the data shown in Figure 5 are much lower than those obtained from the screen viscometer. This difference... 

A simple and useful device for characterising polymer solutions, known as the screen viscometer, was introduced some time ago by Jennings et al (1971). This consists of a small fluid reservoir above a number of screens of known mesh density, as shown in Figure 3.18 in the original apparatus, three 100-mesh screens were recommended. The screen factor, SF, is defined as the following ratio of times ... 

Flow time of volume of polymer solution through screen viscometer Flow time for same volume of solvent through screen viscometer... 

Figure 3.18. Schematic of the screen viscometer for measuring screen factor, SF (Jennings et aU 1971 figure from Lake, 1989).

In oilfield applications, the viscoelastic character of polyacrylamide solutions is evaluated with a simple apparatus called the screen viscometer. The screai viscometer, shown in Fig. 5.42, consists of a bulb with known volume connected to a glass tube. A set of five 100-mesh stainless-steel screens is inserted into a fitting at the end of the glass tube. The screen viscometer is used by determining the times required for known volumes of polymer and brine to flow through the viscometer. The screen factor, F, is defined as the ratio of the flow time for the polymer solution, Afp, to the flow time for the brine, Atf, ... 

The screen factor device used, more commonly designed a screen viscometer due to similarity in appearance to a capillary viscometer, measured the flow time for a fixed volume of solution through a stack of five 100-mesh screens. The screen factor... 

The screening capillary viscometer can be operated manually as well as automatically. If manual operation is desired, an interactive program is available to aid with data collection. Program-operator interaction takes place through terminal input and also with a push-button data collection indicator on the instrument itself. The immediate on-line analysis of results and the ease of data storage and retrieval are just some of the benefits realized by using this program 1n conjunction with manual operation of the instrument. 

The low frequency baseline noise of the viscometer can be substantially reduced by careful filtration of samples and regular checking and maintenance of column end fittings and fractional sections of tubing in the system. Figure 5 shows the effect of column screen replacement on the stability of the baseline signal at a flow rate of 1.0 ml/min. 

Figure 5. Viscometer trace before and after the column screen replacement.

Dense-phase flow properties can be predicted by measuring the viscosity and deaeration rate of a fluidized bed in a laboratory test (117). This method appears to be especially useful for evaluating the flow characteristics in standpipes. The viscosity is measured by means of a Brookfield viscometer, which consists of a cylindrical wire-screen spindle rotated about its axis by an electric motor through a torsion spring. The torque required to rotate the spindle is measured by displacement of the... 

Another approach is to use a sophisticated viscometer, a rheo-goniometer, to monitor a parameter referred to as G, the storage modulus. In this method, properties are measured under an imposed oscillatory shear. Alternatively, for screening purposes, simple bottle tests can be used in which the gel solution behavior is observed when a bottle holding a gel is tilted in a specified way or inverted. ... 

Viscosities were measured at a shear rate of 12 rpm (14.7 sec M using a calibrated Brookfield LVT viscometer equipped with a UL adapter. Screen-... 

Filtration ratio was computed as the ratio of the time of the second 50 ml to that of the last 50 ml of 250 ml polymer solution flowing through 2 micron Nuclepore filters (47mm) with 80 psi across the filter. Viscosity of the emulsion was measured with a Brookfield model LVT viscometer, using a number 2 spindle. Dilute solutions of the polymer were prepared (500 ppm active polymer in 0.3% NaCl) and viscosities were measured using a Brookfield LVT with UL adapter at 12 RFM. This 500 ppm solution was also used for screen factor and filtration ratio measurements. Filtration ratio measurements, as well as those of the viscosity of the emulsion concentrate and dilute solutions made from it were consistent, whether measured at the field laboratory or at the production plant of the supplier. 

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