Practice and answer pack
Production calculations problem set and screening checklist
Practice inflow coefficients, local velocity, retention arithmetic and the limits of simple screening equations with explicit pressure and volume bases.
By PetroCalcHub Team · Updated October 24, 2026 · Free to read and use
Begin with the requested quantity
PI, production rate, actual velocity and nominal retention time have different units. Identify the unknown before selecting a formula.
The baseline uses a straight-line inflow model and a fixed PI. Additional exercises change drawdown, pipe diameter and effective vessel volume separately.
Keep independent constraints independent
A low actual velocity relative to an empirical screen does not establish corrosion resistance. A sufficient liquid retention time does not establish gas separation capacity.
Write a separate line for each check rather than combining their outputs into one unqualified pass statement.
Explain what the calculator can establish
The available scalar calculators evaluate their documented relations. They do not automatically couple reservoir inflow, tubing outflow and surface facilities.
The printable answer key includes model-scope questions so the calculation is connected to the decision it can support.
Explore the example
Original synthetic teaching calculation. Equations and fixed controls are stated here; these are not field measurements.
Select one of 5 recorded scenarios. Intermediate states are not interpolated.
Drawdown (psi) = 500. Oil rate (STB/day): 1000; PI (STB/day/psi): 2.
- Oil rate (STB/day)
Worked example
Fixed PI, changing drawdown
Linear PI J = 2 STB/day/psi; pressures use one compatible datum and fluid-volume basis.
Relation and unit basis
q = J Δp
This is an inflow relation. An operating point additionally requires an outflow model.
1. Define the baseline
Drawdown (psi) = 500
Linear PI J = 2 STB/day/psi; pressures use one compatible datum and fluid-volume basis.
2. Select the relation
q = J Δp
This is an inflow relation. An operating point additionally requires an outflow model.
3. Substitute the values
2 STB/day/psi × 500 psi = 1,000 STB/day
Retain intermediate precision. The displayed values are rounded only after evaluation.
4. Read the result
Oil rate (STB/day) = 1000; PI (STB/day/psi) = 2
PI is a coefficient, while rate depends on the selected drawdown.
Result and interpretation
Oil rate (STB/day) = 1000; PI (STB/day/psi) = 2
PI is a coefficient, while rate depends on the selected drawdown.
Solve the PI example, then use the additional exercises to distinguish inflow, geometry and facility constraints.
Exact scenario data
Original synthetic teaching calculation. Equations and fixed controls are stated here; these are not field measurements.
| Drawdown (psi) | Oil rate (STB/day) | PI (STB/day/psi) |
|---|---|---|
| 100 | 200 | 2 |
| 250 | 500 | 2 |
| 500 | 1,000 | 2 |
| 750 | 1,500 | 2 |
| 1,000 | 2,000 | 2 |
Scroll the table to see all columns. The highlighted row is the worked baseline. Downloads retain full numerical precision.
Practice problems and answer key
Work through the question before revealing its answer. Use the stated assumptions and include units in every numerical step.
1. Which input is still needed to convert PI into a straight-line rate?
Show the worked answer
Pressure drawdown on a compatible reservoir and flowing-pressure basis.
2. Reproduce the baseline Oil rate (STB/day) without rounding intermediate values.
Show the worked answer
2 STB/day/psi × 500 psi = 1,000 STB/day. Oil rate (STB/day) = 1000. PI is a coefficient, while rate depends on the selected drawdown.
3. Compare the first and last recorded scenarios. Which input changes?
Show the worked answer
Drawdown (psi) changes from 100 to 1000. Other controls remain as stated in the premise. Oil rate (STB/day) changes from 200 to 2000.
4. What would be needed to apply this example to a different physical system?
Show the worked answer
Replace the synthetic controls with compatible documented inputs and check the relation's assumptions. This is an inflow relation. An operating point additionally requires an outflow model. PI is a coefficient, while rate depends on the selected drawdown.
5. What happens to actual pipe speed if ID doubles at fixed local Q?
Show the worked answer
It becomes one quarter because cross-sectional area increases fourfold.
6. Compare nominal liquid retention for 10 m³ effective volume at 2 and 4 m³/min.
Show the worked answer
5 and 2.5 min respectively. A gas-side separation-capacity check is still independent.
Before using the result
- Identify the requested quantity and units.
- Keep local and standard rates distinct.
- State the scope of each screen.
PI is a coefficient, while rate depends on the selected drawdown.
Continue learning
Start with the broader workflow guide · Related method guide
Sources and method
The explanation and synthetic examples are original PetroCalcHub teaching material. The references below support the definitions and model context. They do not supply field validation for the synthetic scenarios.