Petroleum Aquifer Productivity Index Calculator
Extract actual independently assessed interval aquifer inflow/pressure-margin PI and unexplained intercept, not suppliedPI water-influx forecast. Caller independently verifies units, applicability and matching conditions; no operational recipe, safety certification, causal efficacy or legal/resource classification is inferred.
Description
Aquifer productivity can be summarized by fitting interval-average inflow rate against a matched pressure margin.
Aquifer productivity can be summarized by fitting interval-average inflow rate against a matched pressure margin.1
This tool derives rates from supplied interval volumes and durations, retaining a free intercept for unexplained inflow.
When to use Petroleum Aquifer Productivity Index Calculator
Use this tool when you need to calculate the stated measurement summary or conditional model from matched observations. Prepare completed matched measurements, SI or explicitly stated oilfield units, and independent evidence for the selected branch or calibration.
How to use Petroleum Aquifer Productivity Index Calculator and understand its results
- Prepare completed matched measurements, SI or explicitly stated oilfield units, and independent evidence for the selected branch or calibration.
- Enter observedAquiferInfluxVolumesM3, observedIntervalDays, observedMatchedPressureMarginsPa, following the field table and calculation rules below, then run the tool.
- Read fittedObservedAquiferPiM3DayPa, fittedUnexplainedInfluxM3Day, aquiferPiFitRSquared. For result objects, inspect the nested output fields below, including any missing evidence or selected indices.
- Correct any input issues and run again. Before using a successful result, review its units, signs, evidence coverage, and stated model or reference assumptions.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| observedAquiferInfluxVolumesM3 | Observed aquifer influx volumes m3 | list of number | Required |
| observedIntervalDays | Observed interval days | list of number | Required |
| observedMatchedPressureMarginsPa | Observed matched pressure margins pa; pressure or stress in pascals, with the sign convention described above. | list of number | Required |
Require nonempty aligned nonnegative influx volumes and pressure margins, with positive interval days. Divide each volume by its interval duration and fit rate against margin using at least two pairs and nonzero margin variance. Return the signed slope in m³/day/Pa, intercept in m³/day, and R² without forcing a zero intercept or positive PI.
The regression helper accepts 2–10000 aligned finite pairs with nonzero predictor variance. It fits ordinary least squares with a free intercept using shifted coordinates; samples need not be sorted unless this tool additionally requires it. R² is clamped to [0,1] and is one for constant responses. Transformed fits use the stated predictor/response basis. Only fields present in this tool’s output are returned; an internal R² calculation does not add an undocumented output. R² is a fit summary rather than a confidence interval.
volume_i/days_i≈PI×margin_i+unexplainedInflux Read these symbols with the field meanings and branch or reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| fittedObservedAquiferPiM3DayPa | Fitted observed aquifer pi m3 day pa; pressure or stress in pascals, with the sign convention described above. | number |
| fittedUnexplainedInfluxM3Day | Fitted unexplained influx m3 day; volume rate in cubic metres per day. | number |
| aquiferPiFitRSquared | Aquifer pi fit r squared | number |
{
"input": {
"observedAquiferInfluxVolumesM3": [
2,
4,
6
],
"observedIntervalDays": [
1,
1,
1
],
"observedMatchedPressureMarginsPa": [
1,
2,
3
]
},
"output": {
"fittedObservedAquiferPiM3DayPa": 2,
"fittedUnexplainedInfluxM3Day": 0,
"aquiferPiFitRSquared": 1
}
}Limitations and assumptions
Measurements, unit conventions, branch identity, and model applicability must be independently established. The result does not infer a complete reservoir or flow model, operational settings, or a reserve classification.
Missing required fields, unknown fields, wrong types, and violated calculation rules return input issues. Numeric values must be finite; nonfinite numeric outputs are rejected. Arrays must be dense, with no missing cells. Numeric lists allow at most 10000 entries, subject to smaller tool-specific bounds above.
Alternative or Complementary methods
For a related task, use Petroleum Water Influx Steady State Schilthuis Calculator: Schilthuis steady aquifer influx integrates pressure deficit over time using a supplied aquifer productivity index. This tool uses the observed boundary-pressure history and retains negative contributions when boundary pressure exceeds the undepleted reference. For a complementary step, use Petroleum Water Influx Unsteady State Van Everdingen Hurst Calculator: Van Everdingen–Hurst superposition relates a pressure-step history to a verified aquifer unit-step response. This tool sums responses from a supplied kernel and normalization instead of solving or assuming the aquifer response function.
References
Similar or alternative tools
- Petroleum Water Influx Steady State Schilthuis Calculator
Schilthuis steady aquifer influx integrates pressure deficit over time using a supplied aquifer productivity index. This tool uses the observed boundary-pressure history and retains negative contributions when boundary pressure exceeds the undepleted reference.
- Petroleum Water Influx Unsteady State Van Everdingen Hurst Calculator
Van Everdingen–Hurst superposition relates a pressure-step history to a verified aquifer unit-step response. This tool sums responses from a supplied kernel and normalization instead of solving or assuming the aquifer response function.