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Reservoir EngineeringUnconventional Reservoirs

Adsorbed Gas Recovery Factor from Langmuir Pressures Formula

RFads=1Pab/(PL+Pab)Pi/(PL+Pi)RF_{ads} = 1 - \frac{P_{ab}/(P_L+P_{ab})}{P_i/(P_L+P_i)}

Adsorbed Gas Recovery Factor from Langmuir Pressures calculates adsorbed gas recovery factor for unconventional reservoirs workflows in reservoir engineering.

Calculate

How engineers use this formula

Use this formula when the listed inputs (P_i, P_ab, P_L) are known and the assumptions behind the cited unconventional reservoirs 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, RF_ads equals 0.142857 fraction.

P_ipsi

1000

P_abpsi

500

P_Lpsi

200

Inputs

P_i

psi

Initial Reservoir Pressure

P_ab

psi

Abandonment Reservoir Pressure

P_L

psi

Langmuir Pressure

Outputs

RF_ads

fraction

Adsorbed Gas Recovery Factor

P_i

psi

Initial Reservoir Pressure

P_ab

psi

Abandonment Reservoir Pressure

P_L

psi

Langmuir Pressure

Source and review

reviewed

Derived from Ahmed and McKinney's Langmuir adsorption relationship for coalbed methane.

Source

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