Fann viscometer

Tests were conducted to compare the effect of KC1 and TKPP on the rheology of an unweighted (nondispersed) and a weighted (dispersed) drilling fluid. All fluids were mixed in an industry standard Hamilton Beach mixer. The rheology of each fluid was then measured in a Fann viscometer at 120°F at 300 rpm and 600 rpm. 

Elevated Temperature Testing. The tests in the RSIV were conducted only at ambient temperature. Elevated-temperature tests were conducted by using a Fann viscometer, a Rheometrics pressure rheometer (RPR), and a reciprocating capillary viscometer. The basic test procedure used for testing at 80 C with the Fann viscometer and reciprocating capillary viscometer is as follows. 

Figure 11. Viscosity vs. shear rate relationship of PS-7 Fann Viscometer Model 35A 0.28% cone = 1 Ib/bbl...

A range of rotational instruments are available which function like the concentric cylinder rheometer described earlier. For example, the Fann viscometer. 

This unusual effect is a property of only a few select water-soluble polymers, among which are the extensive family of acrylamide polymers and copofymers. The exact flow mechanism which causes this resistance factor has not been established but it does appear to be a complex combination of several factors. Although polymer solutions are generally highly non-Newtonian, this is not the only factor. The resistance factor is substantially constant over normal field fluid advance rates as shown in Fig. 2, which also shows the slope line and range of the viscosity-shear rate data from 4.8 to 960 sec determined with a Fann viscometer. Since the shear... 

Historically, viscosity measurements have been the single most important method to characterize fluids in petroleum-producing applications. Whereas the ability to measure a fluid s resistance to flow has been available in the laboratory for a long time, a need to measure the fluid properties at the well site has prompted the development of more portable and less sophisticated viscosity-measuring devices [1395]. These instruments must be durable and simple enough to be used by persons with a wide range of technical skills. As a result, the Marsh funnel and the Fann concentric cylinder, both variable-speed viscometers, have found wide use. In some instances, the Brookfield viscometer has also been used. 

A number of Fann or Baroid rheometers have been used for the rig site measurement of fluid rheology (62, 63). The design of the rheometers is similar and the various viscometer types differ largely in the control of shear rate. Early models of the concentric cylinder rheometer were limited to two shear rate measurements made at rotation speeds of r = 300 rpm and r = 600 rpm. Later models have extended the number of rotational speeds (shear rates) at which the torque can be measured, enabling a more complete rheogram to be constructed. 

Figure 67. Comparison of Bingham plastic viscosity (in cP) obtained from a Fann concentric viscometer and an on-line pipe rheometer. (Data from reference 161.)...

Figure 16. Reproducibility of viscosity data taken on Fann 50, RPR, and capillary viscometers.

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