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Generalized Archie Formation Factor with Lithology Coefficient Formula

F=aϕmF=\frac{a}{\phi^m}

Generalized Archie Formation Factor with Lithology Coefficient calculates formation factor for electrical properties workflows in petrophysics.

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How engineers use this formula

Use this formula when the listed inputs (a, phi, m) 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, F equals 25 dimensionless.

adimensionless

1

phifraction

0.2

mdimensionless

2

Inputs

a

dimensionless

Archie Lithology Coefficient

phi

fraction

Porosity

m

dimensionless

Cementation Exponent

Outputs

F

dimensionless

Formation Factor

a

dimensionless

Archie Lithology Coefficient

phi

fraction

Porosity

m

dimensionless

Cementation Exponent

Source and review

reviewed

SLB Energy Glossary. Formation factor; AAPG Wiki. Archie equation.

Source

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