Page 138 - A Practical Companion to Reservoir Stimulation

J. Stimulation of Horizontal Wells

EXAMPLE J-1
Figure J- 1 contains the expected flow rates for the two well
Deliverability of a Damaged Horizontal Gas Well lengths, for a range of skin effects (damaged horizontal
well). If the skin effect is equal to zero (no damage), then the
Estimate the steady-state flow rate for a horizontal gas well well production rate (for L = 1000 ft) will be approximately 1
using lengths of 1000 ft and 1500 ft, respectively, and for a MMSCF/d. For a well with moderate damage (s = 5), the rate
range of skin effects. Table J-1 contains the relevan! well and will be approximately 350 MSCF/d.
reservoir data. As can be seen for a 1500-ft well, the nondamage produc-
tion rate is 1300 MSCF/d (a gain of 300 MSCF/d over the
Solution (Ref. Section 19-2) 1000-ft well). The damaged well would not gain appreciably
Equation 19-3 is for an oil well. (While Eq. 19-3 in the over the 1000-ft well. This is important because lack of
textbook is as published by Joshi (SPE 15375,1986;JPT June stimulation may reduce significantly the expected benefits
1988), it has been shown by Economides et al. (SPE 20717, from a longer well.
1990) that it must be augmented. The term 2rW must be re-
placed by (0 + l)rw.. All calculations in this volume use this
correction.) It can be readily modified for a gas well, and kH = 0.1 md
using oilfield units, it becomes
,U = 0.0219~~
kH (P2 - P$) I h = 25ft I
4=
(If Y (12- (Ll?)'
pll
1424pzT n- L12 + -In I Z = 0.925 I
L (P+ I)r,,
where a can be obtained from Eq. 19-2. The skin effect has I p = 5068psi I
been added to the denominator in the usual manner. T = 650"R [190°F]
If L = 1000 ft and since reH = 2107 ft, then from Eq. 19-2, pwr = 2000psi
a = 21 37 ft. Substituting all known variables from Table J-1
into Eq. J- 1 results in
2591 I r, = 0.229 ft I
4=
2.46 + s A = 320 acres [reH = 21 07 ft]
The calculation, repeated for L = 1500 ft, leads to a = 2175 Table J-1-Well and reservoir data for Example J-I.
ft, and from Eq. J- 1,

259 1
q= ~ (5-3)
1.95 + s

J- 1