Friction correcting

F is a friction correction factor. For screening purposes, this has been taken as 1 (no friction) for comparison with a relief area for case.(iii) which also ignores friction. 

Figure A8.3 can now be used to obtain a friction correction factor, given = 0.099 and 4fL/D = 2.4. Reading from the graph gives a correction factor of 0.6.

Alternatively, equation (9.10) (jives an approximate value for the correction factor. For the ERM, Fauskef17] gave a Table of friction correction factors as a function of the equivalent length to diameter ratio. These are given inTable5.1 and tend to be quite conservative compared with values estimated using the Omega method. 

Table 5.1 Friction correction factors for use with the simplified ERM1171...

FRICTIONAL CORRECTION FACTORS FOR USE WITH FAUSKE S METHOD. ... 

Reading from Figure A8.3 with 4fL/D = 3.6 gives a friction correction factor, G/Gc = 0.73. 

Reading from Figure A8.3 for =4fL/D =1.9 and = 1, gives a friction correction factor of 07) Figure A87 indicates that the critical pressure ratio is 0.4. This exceeds the available pressure ratio (venting to atmospheric pressure) of 1/5.4 = 0.185, and so flow is choked. Therefore no correction is needed for non-choked flow. 

Figure 7. Correlation for proppant friction correction factor—5.5 in. csg, 1.9-in. tubing annulus. (Reproduced with permission from reference 29. Copyright 1983 Society of Petroleum Engineers.)...

For friction loss of slurries Cooper et al. (38) presented the friction correction factor shown in Figure 14. The authors claim that it is based on a theoretical method of predicting friction pressures of non-Newtonian fluids. The method assumes vertical flow, no hold-up effect, and pseudohomogeneous characteristics. However, the details of the method are not presented in open literature. It is shown in their article that the modeled effect on friction pressures is consistent with a field study conducted by Swanson and Meeken (39). 

Ttest procedures Maximum permissible frictional loss without specimen 0.02% for 0.5 to 5.0 J pendulum 0.04% for 7.5 J pendulum 0.05% for 15.0 J pendulum 0.10% for 25.0 J pendulum 0.20% for 50.0 J pendulum Windage and friction correction are not mandatory, however, a method of determining these values is given. 

Section 10.3 treated mutual diffusion of colloidal spheres. To summarize significant results the low-concentration dependence of D on (j) is close to zero, in reasonable agreement with models based on the assertion that Dm 4>) of colloidal spheres is determined by the direct and hydrodynamic interactions of the spheres, and that (as also found for Ds) dynamic friction corrections are not large at short times. The value of Dmiinitial slope ko decreases markedly with increasing q at large Dm (q) approaches Ds, as expected theoretically. 

Determine the shear stress constant, Ks, the shear rate constant, K, and the friction correction F, as follows ... 

Determine the friction correction, F, in grams by one of the following methods ... 

Determine the friction correction F from the plot of 7.1.2 as the intercept with the abscissa. 

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