Page 116 - Formulas and Calculations for Petroleum Engineering

Drilling engineering formulas and calculations Chapter 2 109

2.79 Equivalent density of a wellbore fluid

Input(s)
M w : Mud Weight (ppg)
TVD: True Vertical Depth (ft)
APL: Annular Pressure Loss (psi)

Output(s)
ECD: Equivalent Circulating Density (ppg)

Formula(s)

APL
ECD ¼ +M w
0:052 TVD
Reference: Lapeyrouse, N. J., 2002, Formulas and Calculations for Drilling, Production and Workover, Second Edition,
Gulf Professional Publishing, Page: 6.

2.80 Equivalent formation water resistivity from SP log

Input(s)
R mfeq : Equivalent Resistivity of Mud Filtrate (ohm m)
SSP: Static Spontaneous Potential (mV)
T: Temperature (F)

Output(s)

R weq : Equivalent Formation Water Resistivity (ohm m)

Formula(s)

R mfeq
R ¼ 61 + 0:133 TÞ
ð
weq SSP

10 61 + 0:133 T
Reference: Core Laboratories. 2005. Formation Evaluation and Petrophysics, Page: 74.

2.81 Equivalent mud weight—Deviated well
Input(s)

P h : Pressure (psi)
D h : Measured Depth (ft)
a: Deviation Angle (degree)

Output(s)

EMW: Equivalent Mud Weight (ppg)