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Reservoir EngineeringRock Properties

Maximum Oil Column Height in Cap Rock Formula

H=PaPw+Gohα+PcρGoH=\frac{P_a-P_w+G_oh\alpha+P_c}{\rho-G_o}

Maximum Oil Column Height in Cap Rock calculates maximum oil column height for rock properties workflows in reservoir engineering.

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How engineers use this formula

Use this formula when the listed inputs (P_a, P_w, G_o, h, alpha, P_c, rho) 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, H equals 11,300 ft.

P_apsi

5000

P_wpsi

4200

G_opsi/ft

0.35

hft

1000

alphadimensionless

0.8

P_cpsi

50

rhopsi/ft

0.45

Inputs

P_a

psi

Total Potential Energy of Accumulation

P_w

psi

Water Potential in Reservoir

G_o

psi/ft

Initial Oil Pressure Gradient in Reservoir Rock

h

ft

Depth

alpha

dimensionless

Height Constant

P_c

psi

Capillary Pressure

rho

psi/ft

Density Differential Between Fluids

Outputs

H

ft

Maximum Oil Column Height

P_a

psi

Total Potential Energy of Accumulation

P_w

psi

Water Potential in Reservoir

G_o

psi/ft

Initial Oil Pressure Gradient in Reservoir Rock

h

ft

Depth

alpha

dimensionless

Height Constant

P_c

psi

Capillary Pressure

rho

psi/ft

Density Differential Between Fluids

Source and review

reviewed

Advanced Reservoir Engineering, Ahmed, T., McKinney, P.D. (2015)

Ahmed, T. and McKinney, P.D. 2015. Advanced Reservoir Engineering. Gulf Publishing House.

Source

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