Schilthuis Cumulative Water Influx Formula
Schilthuis Cumulative Water Influx calculates cumulative water influx over interval for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (J_s, P_i, P_avg, Delta_t) 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 1,500,000 bbl.
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3500
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Inputs
J_s
bbl/day/psiSchilthuis Aquifer Productivity Index
P_i
psiInitial Reservoir or Boundary Pressure
P_avg
psiAverage Reservoir Pressure During Time Interval
Delta_t
dayTime Interval
Outputs
W_e
Cumulative Water Influx Over Interval
J_s
Schilthuis Aquifer Productivity Index
P_i
Initial Reservoir or Boundary Pressure
P_avg
Average Reservoir Pressure During Time Interval
Delta_t
Time Interval
Source and review
reviewedPetroleum Office. Aquifer Models, Schilthuis steady-state cumulative influx.
Source