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Reservoir EngineeringPressure Transient Analysis

Minimum Shut-In Time to Pseudosteady State for Hydraulically Fractured Tight Gas Reservoirs Formula

tpss=474ϕμgctxf2kt_{pss}=\frac{474 \phi \mu_g c_t x_f^2}{k}

Minimum Shut-In Time to Pseudosteady State for Hydraulically Fractured Tight Gas Reservoirs calculates minimum shut-in time to reach pseudosteady state for pressure transient analysis workflows in reservoir engineering.

Calculate

How engineers use this formula

Use this formula when the listed inputs (phi, mu_g, c_t, x_f, k) 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, t_pss equals 284.4 h.

phifraction

0.08

mu_gcP

0.02

c_t1/psi

0.000015

x_fft

500

kmD

0.01

Inputs

phi

fraction

Porosity

mu_g

cP

Gas viscosity

c_t

1/psi

Total compressibility

x_f

ft

Fracture half-length

k

mD

Permeability

Outputs

t_pss

h

Minimum shut-in time to reach pseudosteady state

phi

fraction

Porosity

mu_g

cP

Gas viscosity

c_t

1/psi

Total compressibility

x_f

ft

Fracture half-length

k

mD

Permeability

Source and review

reviewed

Ahmed, T. and McKinney, P. D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 23.

Source

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