PetroCalcHubFree
Reservoir EngineeringPressure Transient Analysis

Dimensionless Length for Fracture Linear Flow Formula

xD=xLfx_D=\frac{x}{L_f}

Dimensionless Length for Fracture Linear Flow calculates dimensionless fracture linear flow length for pressure transient analysis workflows in reservoir engineering.

Calculate

How engineers use this formula

Use this formula when the listed inputs (x, L_f) are known and the assumptions behind the cited pressure transient analysis 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, x_D equals 0.5 dimensionless.

xft

150

L_fft

300

Inputs

x

ft

Linear Flow Distance

L_f

ft

Fracture Half-Length

Outputs

x_D

dimensionless

Dimensionless Fracture Linear Flow Length

x

ft

Linear Flow Distance

L_f

ft

Fracture Half-Length

Source and review

reviewed

Lee, Rollins and Spivey, Pressure Transient Testing, SPE Textbook Series Vol. 9, hydraulically fractured well linear-flow dimensionless variables.

Source

Related formulas and calculators

Average Permeability for Linear Flow in Layered Beds
Permeability
Average Permeability for Linear Flow - Series Beds
Permeability
Average Permeability for Parallel-Layered Systems
Permeability
Average Permeability in Radial Systems
Permeability
Klinkenberg Apparent Gas Permeability
Permeability
Jones-Owens Klinkenberg Slip Factor
Permeability