Page 187 - Formulas and Calculations for Petroleum Engineering

180 Formulas and calculations for petroleum engineering

3.10 Diffusion depth in a geothermal well

Input(s)
w: Mass Flow Rate (lb/h)
o
c: Thermal Heat Capacity of the Fluid (BTU/lbm F)
k: Thermal Conductivity of Earth (¼ 33.6 BTU/(ft day °F))
f(t): Dimensionless Time Function that Represents the Transient Heat Transfer to the formation (dimensionless)

Output(s)
A(t): Diffusion Depth as a Function of Time (ft)

Formula(s)

wcf tðÞ
AtðÞ ¼
2pk

Reference: Ramey Jr, H. J. (1981). Reservoir Engineering Assessment of Geothermal Systems. Department of Petroleum
Engineering, Stanford University. Equation (6–2).

3.11 Dimensionless buildup pressure for field calculations
Input(s)

P i : Initial Reservoir Pressure (psi)
P ws : Shut in Pressure (psi)
2
m: Slope of Semi-Log Graph (kg/cm )/ Log cycle for Liquid

Output(s)
P Ds : Dimensionless Pressure (dimensionless)

Formula(s)

P P ws
i
P ¼
Ds
0:87m
Reference: Ramey Jr, H. J. (1981). Reservoir Engineering Assessment of Geothermal Systems. Department of Petroleum
Engineering, Stanford University, Page: (5.8).

3.12 Dimensionless buildup pressure for liquid flow

Input(s)
k: Effective Permeability of Flowing Phase (D)
h: Net Formation Thickness (m)
P i : Initial Reservoir Pressure (psi)
P ws : Shut in Pressure (psi)
v sc : Specific Volume at Standard Conditions (cc/g)
q: Production Rate (tons/h (1000 kg/h))
B: Formation Volume Factor (Reservoir Volume/Standard Volume)
m: Viscosity of Flowing Fluid (cP)