Page 154 - A Practical Companion to Reservoir Stimulation

PRACTICAL COMPANION TO RESERVOIR STIMULATION

EXAMPLE 5-7 EXAMPLE 5-8

Reduction of the Skin Effect of a Interference Among Multiple Parallel Fractures
lkansversely Fractured Horizontal Well
What would be the increase in the excess pressure during
Assuming that k = 1 md, h = 100 ft and r, = 0.328 ft, outline fracturing and the decrease in the fracture width if a second
a technique to reduce the choke skin effect. fracture is completed 100 ft or 500 ft away from an existing
500-ft half-length fracture.
Solution (Ref. Section 19-6)
From Eq. 19-40, Solution (Ref. Section 19-5.2.3)
Figure 19-2 1 shows a correlation for the solution to this prob-
100 lem. The ratioy/xfis equal to (100/2)/500 = 0.1 if the distance
(I) ('O0) [In (2) (0.328) is 100 ft, and equal to 0.5 if the distance is 500 ft. Thus, the
(SC/,)C = - IS,]
kf
width ratio and the pressure ratio for the 100-ft distance are
345 0.85 and 1.64, respectively. For the 500-ft distance, they are
- (5-23) 0.96 and 1.1, respectively. This denotes the very significant
--
k.1 impact of fracture spacing on their interference. In general, if
It is then obvious that if k,w is large, (s,.{JC is small. A way to y/xf- 1, there is virtually no interference.
accomplish this is to make the near wellbore krw as large as
possible. Thus, tailing in with high-strength proppants or
resin-coated proppants is indicated.

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