Page 40 - A Practical Companion to Reservoir Stimulation

C. Fracturing Fluids and Proppants

EXAMPLE C-1
From Table 5- 1 the consistency index for pipe and slot can
Determination of Rheological Properties be calcylated:
of Power Law Fluids

A hydraulic fracturing fluid has exhibited the experimentally
determined behavior shown in Fig. C-1. These'data were
measured in a concentric cylinder viscometer. Calculate the and
power law constants, determine the consistency for a pipe
and a slot, and plot the apparent viscosity in a pipe for shear
rates from 1 to I 0-3 sec-I. The ratio of the radius of the cup to
that of the bob in the viscometer was equal to 2.
Finally, the apparent viscosity (again from Table 5-1) is given
Solution (Ref. Sections 5-2.2 and 5-2.3) for a pipe by
From Fig. C- I, the slope is equal to 0.36, and thus n = n ' =
0.36. The consistency index K,, 0.21 lbf sec"'lft', which is 47,880 (0.143) - 6847
=
--
obtained from the intercept at y = 1. From the top equation in Po = Y'-o.36 yo. 64. (C-5)
Table 5- 1 (and noting that p = 2),
A graph of the apparent viscosity vs. shear rate is shown in
Fig. C-2.

Then, the power law for this fluid is from Eq. 5-4:
T~~ = 0.125.jo.36. (C-2)

c- 1