Page 250 - Formulas and Calculations for Petroleum Engineering

Production engineering formulas and calculations Chapter 4 243

h p
A ¼
h
t
h a
B ¼
h
t
h
0 1 0 0 10:5 11

0
p
! 1
1 B 3:142 C 1 B h pd B B h t C CC
B
C
s ¼ 1 2:303 log 0:5 C + B B B C CC
p B 0:5 lnB B CC
h A h 2+ h @ h A
pd @ rw k v pd @ pd @ a AA
1
h t k h h t
Reference: Pressure Transient Testing, Lee, Rollins & Spivey, Page: 44.
4.86 Skin factor due to reduced crushed-zone permeability
Input(s)
h p : Perforation interval (ft)
kd: Damage Zone permeability (mD)
kdp: Crushed Zone Permeability (mD)
k: Permeability of Formation (mD)
r dp : Crushed Zone radius (ft)
r p : Perforation Radius (ft)
Lp: Depth of Penetration (ft)
N: Total Number of Perforations (number)

Output(s)

sc: Skin Factor due to Reduced Crushed-Zone Permeability (dimensionless)

Formula(s)

!

k k h p r dp
sc ¼ 12 ln
kdp kd N Lp r p
Reference: Horizontal Well Technology, Joshi, Page: 504.

4.87 Skin factor for a deviated well

Input(s)
θ: Angle of Inclination (degree)
kv: Vertical Permeability (mD)
kh: Horizontal Permeability (mD)
h: Formation Thickness (ft)
rw: Radius of Wellbore (ft)
s: Total Skin Factor (dimensionless)

Output(s)
tw: Angle of Inclination due to drilling (degree)