PetrophysicsRock Properties

Stieber Shale Volume from Gamma Ray Index Formula

V_{sh}=\frac{I_{GR}}{3-2I_{GR}}

Stieber Shale Volume from Gamma Ray Index calculates stieber shale volume for rock properties workflows in petrophysics.

Calculate

How engineers use this formula

Use this formula when the listed inputs (I_GR) 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, V_sh equals 0.181818 fraction.

I_GRfraction

0.4

Inputs

I_GR

fraction

Gamma Ray Index

Outputs

V_sh

fraction

Stieber Shale Volume

I_GR

fraction

Gamma Ray Index

Source and review

reviewed

Stieber, S.J. 1970. Pulsed Neutron Capture Log Evaluation: Louisiana Gulf Coast, SPE 2961; Aptian Technical gamma-ray shale-volume crossplot references.

Source