Petroleum Well Test Permeability Calculator
Infer radial-test permeability from actual pressure versus NATURAL LOG elapsed time slope with SI qμB/(4πhm), not log10 oilfield unit constant or steady Darcy core permeability; caller independently selects regime. Caller independently verifies units, applicability and matching conditions; no operational recipe, safety certification, causal efficacy or legal/resource classification is inferred.
Description
A constant-rate radial pressure test can relate pressure slope against natural log of elapsed time to permeability.
A constant-rate radial pressure test can relate pressure slope against natural log of elapsed time to permeability.1
This tool fits independently selected radial observations and applies the SI pressure-slope relation using supplied fluid and well properties.
When to use Petroleum Well Test Permeability 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 Permeability 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 observedRadialTestElapsedSeconds, observedNaturalLogDrawdownPa, observedStockFlowM3Second, observedFluidViscosityPaSeconds, callerMatchedFormationVolumeFactor, observedNetPayThicknessM, callerInfiniteActingRadialBranchVerified, following the field table and calculation rules below, then run the tool.
- Read radialTestInferredPermeabilityM2, naturalLogPressureSlopePa. 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 |
|---|---|---|---|
| observedRadialTestElapsedSeconds | Observed radial test elapsed seconds | list of number | Required |
| observedNaturalLogDrawdownPa | Observed natural log drawdown pa; pressure or stress in pascals, with the sign convention described above. | list of number | Required |
| observedStockFlowM3Second | Observed stock flow m3 second | number | Required |
| observedFluidViscosityPaSeconds | Observed fluid viscosity pa seconds | number | Required |
| callerMatchedFormationVolumeFactor | Caller matched formation volume factor | number | Required |
| observedNetPayThicknessM | Observed net pay thickness m | number | Required |
| callerInfiniteActingRadialBranchVerified | Caller infinite acting radial branch verified | boolean | Required |
Require positive elapsed seconds, viscosity in Pa·s, formation-volume factor, and pay thickness in metres; require nonnegative drawdowns and stock flow in m³/s and explicit radial-branch verification true. Fit drawdown against ln(time), require positive fitted slope, and divide qμB by 4πh times that slope. Zero stock flow is accepted. The slope is per natural-log unit, not per log10 decade.
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.
k_m2=q_stock μB/(4πh m_ln) Read these symbols with the field meanings and branch or reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| radialTestInferredPermeabilityM2 | Radial test inferred permeability m2 | number |
| naturalLogPressureSlopePa | Natural log pressure slope pa; pressure or stress in pascals, with the sign convention described above. | number |
{
"input": {
"observedRadialTestElapsedSeconds": [
1,
2.718281828459045,
7.3890560989306495
],
"observedNaturalLogDrawdownPa": [
1,
2,
3
],
"observedStockFlowM3Second": 1,
"observedFluidViscosityPaSeconds": 1,
"callerMatchedFormationVolumeFactor": 1,
"observedNetPayThicknessM": 1,
"callerInfiniteActingRadialBranchVerified": true
},
"output": {
"radialTestInferredPermeabilityM2": 0.07957747154594767,
"naturalLogPressureSlopePa": 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 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. For a complementary step, use Petroleum Horner Plot Slope Calculator: A Horner buildup plot uses the logarithm of prior-flow-plus-shut-in time divided by shut-in time. This tool fits observed buildup pressure against base-ten Horner coordinates and preserves the signed fitted slope.
References
Similar or alternative tools
- 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.
- Petroleum Horner Plot Slope Calculator
A Horner buildup plot uses the logarithm of prior-flow-plus-shut-in time divided by shut-in time. This tool fits observed buildup pressure against base-ten Horner coordinates and preserves the signed fitted slope.