Page 186 - Formulas and Calculations for Petroleum Engineering

Well test analysis formulas and calculations Chapter 3 179

3.8 Calculation of pressure beyond the wellbore (line-source solution)

Input(s)
P i : Initial Pressure (psi)
t: Time of Production (h)
k: Permeability (mD)
B: Volume Factor (RB/STB)
ø: Porosity (fraction)
c t : Compressibility (1/psi)
h: Thickness of Reservoir (ft)
m: Viscosity of Oil (cP)
r: Radius of Wellbore (ft)
q: Flow Rate (STB/day)

Output(s)
P: Pressure (psi)

Formula(s)

2
r
ln 1:688 ø m c
t
k t
P ¼ P +70:6 q B m
i
k h
Reference: Lee, J., Rollins, J. B., & Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: SPE,
Page: 11.

3.9 Conventional DST design without a water cushion (collapse pressure calculation)
Input(s)

g w : Water Gradient (psi/ft)
W m : Mud Weight (lbm/gal)
D c : Depth (ft)
F d : Design Factor (dimensionless)
W w : Water Weight (lbm/gal)

Output(s)
p collapse : Collapse Pressure (psi)

Formula(s)

g W D F d
m
c
w
p ¼
collapse
W
w
Reference: Lee, J., Rollins, J. B., & Spivey, J. P. (2003). Pressure Transient Testing (Vol. 9). Richardson, Texas: Society of
Petroleum Engineers, Page: 153.