Petroleum Well Test Storage Coefficient Calculator
Extract actual early wellbore storage from independently measured withdrawn volume/drawdown trace, retain signed fit evidence and offset, no reservoir compressibility or automatic regime assignment. Caller independently verifies units, applicability and matching conditions; no operational recipe, safety certification, causal efficacy or legal/resource classification is inferred.
Description
During a wellbore-storage-dominated test interval, withdrawn volume can vary approximately linearly with pressure drawdown.
During a wellbore-storage-dominated test interval, withdrawn volume can vary approximately linearly with pressure drawdown.1
This tool fits the supplied early measurements and exposes both an apparent storage slope and a volume offset.
When to use Petroleum Well Test Storage Coefficient 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 Well Test Storage Coefficient 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 observedEarlyTestPressureDrawdownPa, observedIndependentlyWithdrawnWellboreVolumeM3, callerEarlyStorageDominatedBranchVerified, following the field table and calculation rules below, then run the tool.
- Read fittedObservedWellboreStorageM3Pa, fittedWellboreVolumeOffsetM3. 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 |
|---|---|---|---|
| observedEarlyTestPressureDrawdownPa | Observed early test pressure drawdown pa; pressure or stress in pascals, with the sign convention described above. | list of number | Required |
| observedIndependentlyWithdrawnWellboreVolumeM3 | Observed independently withdrawn wellbore volume m3 | list of number | Required |
| callerEarlyStorageDominatedBranchVerified | Caller early storage dominated branch verified | boolean | Required |
Require nonnegative aligned drawdown pressures and independently withdrawn volumes, at least two observations with nonzero pressure variance, and callerEarlyStorageDominatedBranchVerified=true. Fit volume against pressure with a free intercept. Retain a signed slope rather than forcing a positive storage result; the branch flag is an assertion supplied by the caller.
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≈storage×drawdown+offset Read these symbols with the field meanings and branch or reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| fittedObservedWellboreStorageM3Pa | Fitted observed wellbore storage m3 pa; pressure or stress in pascals, with the sign convention described above. | number |
| fittedWellboreVolumeOffsetM3 | Fitted wellbore volume offset m3 | number |
{
"input": {
"observedEarlyTestPressureDrawdownPa": [
1,
2,
3
],
"observedIndependentlyWithdrawnWellboreVolumeM3": [
2,
4,
6
],
"callerEarlyStorageDominatedBranchVerified": true
},
"output": {
"fittedObservedWellboreStorageM3Pa": 2,
"fittedWellboreVolumeOffsetM3": 0
}
}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 Well Test Permeability Calculator: A constant-rate radial pressure test can relate pressure slope against natural log of elapsed time to permeability. This tool fits independently selected radial observations and applies the SI pressure-slope relation using supplied fluid and well properties. For a complementary step, use Petroleum Drawdown Pressure Analysis Calculator: Drawdown analysis can summarize a selected pressure branch by fitting pressure change against natural log of elapsed time. This tool retains the signed slope and its difference from an independently supplied reference rather than selecting a radial regime.
References
Similar or alternative tools
- Petroleum Well Test Permeability Calculator
A constant-rate radial pressure test can relate pressure slope against natural log of elapsed time to permeability. This tool fits independently selected radial observations and applies the SI pressure-slope relation using supplied fluid and well properties.
- Petroleum Drawdown Pressure Analysis Calculator
Drawdown analysis can summarize a selected pressure branch by fitting pressure change against natural log of elapsed time. This tool retains the signed slope and its difference from an independently supplied reference rather than selecting a radial regime.