PetrophysicsRock Properties
Composite Capture Cross Section of the Formation Schlumberger Thermal Decay Time Tool Formula
Composite Capture Cross Section of the Formation Schlumberger Thermal Decay Time Tool calculates composite capture cross section of formation for rock properties workflows in petrophysics.
How engineers use this formula
Use this formula when the listed inputs (tau) are known and the assumptions behind the cited rock 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, Sigma equals 13 dimensionless.
taus
0.35
Inputs
tau
sTime Required for Neutron Population to Diminish to 37 Percent
Outputs
Sigma
dimensionless
Composite Capture Cross Section of Formation
tau
s
Time Required for Neutron Population to Diminish to 37 Percent
Source and review
reviewedBassiouni, Z. 1994. Theory, Measurement, and Interpretation of Well Logs. SPE Textbook Series Vol. 4, Chapter 9, Page 181.
Source