Page 95 - A Practical Companion to Reservoir Stimulation

PRACTICAL COMPANION TO RESERVOIR STIMULATION

EXAMPLE F-5 EXAMPLE F-6

Fracture Face Damage Apparent Fracture Face Damage

Clay swelling from a water-base fracturing fluid resulted in a Long-term production from a very tight, heavy gas-conden-
permeability impairment of 95% (k/k,=20). If the fracture sate well (1;,=0.328 ft) results in a skin effect during
half-length is 500 ft and the penetration of damage, b,s, is pseudoradial flow equal to -6.4. If the liquid gas condensate
2 in., estimate the impact of this damage on production. extends 20 ft into the reservoir (normal to the fracture),
calculate the apparent reservoir permeability-to-gas reduc-
Solution (Ref. Section 11-4) tion. The fracture half-length, measured early in the life of the
From Eq. 11-20, well, is 1000 ft.
(3.14)(2/ 12)( 19) Solution (Ref. Section 1-4)
Sf.7 = = 9.9~ (F- 18)
(2) (500) The variables on the ordinate of Fig. 1 1-2 1 can be calculated:
and the reciprocal s,:;’ = 100. r,#,, r,.e-.’ (0.328)e+6.4
-
-
From Fig. 11-21 it can be determined that r:/xf = 0.5; -- - = 0.2. (F-19)
-
i.e., there is no impact on the well performance as a result of Xf Xr 1000
this damage. Therefore, from Fig. 11-21, q-’ = 1.2, and thus, sf., = 0.83.
Using Eq. 1 1-20 and rearranging,
k (2) ( 1000) (0.83)
-
-
- + 1 = 27.4. (F-20)
k,s (3.14)(20)
Therefore, the apparent permeability impairment is
( 1 - - 0.96, (F-21)
=
2i.4)
or 96% reduction.

F-4