Dual-Water Brine-Saturated Rock Conductivity Formula
Dual-Water Brine-Saturated Rock Conductivity calculates brine-saturated rock conductivity for electrical properties workflows in petrophysics.
How engineers use this formula
Use this formula when the listed inputs (F_s, C_wf, C_wb, f_dl, Q_v, v_Q) are known and the assumptions behind the cited electrical properties relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, C_o equals 0.052121 1/(ohm m).
20
1
5
0.8
0.05
0.2
Inputs
F_s
dimensionlessShaly-Sand Formation Resistivity Factor
C_wf
1/(ohm m)Free Water Conductivity
C_wb
1/(ohm m)Bound Water Apparent Conductivity
f_dl
dimensionlessDiffuse-Layer Expansion Factor
Q_v
meq/mLVolume Concentration of Clay Exchange Cations
v_Q
mL/meqVolume Equivalent of Exchange Cations
Outputs
C_o
Brine-Saturated Rock Conductivity
F_o
Salinity-Dependent Formation Resistivity Factor
Source and review
reviewedTheory, Measurement, and Interpretation of Well Logs, Bassiouni, Z. (1994)
Bassiouni, Z. 1994. Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4, Chapter 1, Page 19.
Source