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Reservoir EngineeringMaterial Balance

Water Influx from Pot Aquifer Model Formula

We=ctWi(PiP)W_e=c_tW_i(P_i-P)

Water Influx from Pot Aquifer Model calculates cumulative water influx for material balance workflows in reservoir engineering.

Calculate

How engineers use this formula

Use this formula when the listed inputs (c_t, W_i, P_i, P) are known and the assumptions behind the cited material balance 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, W_e equals 70,000 bbl.

c_t1/psi

0.000007

W_ibbl

50000000

P_ipsi

3000

Ppsi

2800

Inputs

c_t

1/psi

Aquifer Total Compressibility

W_i

bbl

Initial Volume of Water in Aquifer

P_i

psi

Initial Reservoir Pressure

P

psi

Current Reservoir Pressure at Oil-Water Contact

Outputs

W_e

bbl

Cumulative Water Influx

c_t

1/psi

Aquifer Total Compressibility

W_i

bbl

Initial Volume of Water in Aquifer

P_i

psi

Initial Reservoir Pressure

P

psi

Current Reservoir Pressure at Oil-Water Contact

Source and review

reviewed

Ahmed, T. Reservoir Engineering Handbook water influx chapter; ScienceDirect cumulative water influx, Pot Aquifer Model.

Source

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