Reservoir EngineeringMaterial Balance
van Everdingen-Hurst Single-Step Water Influx Formula
van Everdingen-Hurst Single-Step Water Influx calculates cumulative water influx for pressure step for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (B_aq, Delta_p, W_eD) 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 12,597 bbl.
B_aqbbl/psi
20.4
Delta_ppsi
5
W_eDdimensionless
123.5
Inputs
B_aq
bbl/psiAquifer Influx Constant
Delta_p
psiPressure Drop Increment
W_eD
dimensionlessDimensionless Cumulative Water Influx
Outputs
W_e
bbl
Cumulative Water Influx for Pressure Step
B_aq
bbl/psi
Aquifer Influx Constant
Delta_p
psi
Pressure Drop Increment
W_eD
dimensionless
Dimensionless Cumulative Water Influx
Source and review
reviewedPetroleum Office. Aquifer Models, van Everdingen-Hurst cumulative influx; Ahmed water-influx worked example.
Source