{
  "version": 1,
  "topic": "RF02",
  "title": "Porosity versus permeability why storage is not flow capacity",
  "createdAt": "2026-10-24",
  "case": {
    "title": "Equal storage, different flow capacity",
    "premise": "Two synthetic rocks have porosity 0.2 and bulk volume 1,000 m³. A fixed linear Darcy geometry and pressure gradient are used to compare k.",
    "formula": "Vpore = φ Vbulk; qDarcy ∝ k at fixed A, ΔP, μ and L",
    "variables": "Pore volume is 200 m³ in every row; flow uses the published field-unit linear Darcy defaults except for k.",
    "steps": [
      {
        "label": "Define the baseline",
        "calculation": "Permeability (mD) = 100",
        "explanation": "Two synthetic rocks have porosity 0.2 and bulk volume 1,000 m³. A fixed linear Darcy geometry and pressure gradient are used to compare k."
      },
      {
        "label": "Select the relation",
        "calculation": "Vpore = φ Vbulk; qDarcy ∝ k at fixed A, ΔP, μ and L",
        "explanation": "Pore volume is 200 m³ in every row; flow uses the published field-unit linear Darcy defaults except for k."
      },
      {
        "label": "Substitute the values",
        "calculation": "Vpore = 0.2 × 1,000 = 200 m³; at k = 100 mD, q = 0.001127 × 100 × 500 × 100/(2 × 1,000) = 2.8175 bbl/day",
        "explanation": "Retain intermediate precision. The displayed values are rounded only after evaluation."
      },
      {
        "label": "Read the result",
        "calculation": "Darcy local rate (bbl/day) = 2.8175; Pore volume (m³) = 200",
        "explanation": "Permeability changes flow capacity without changing the stipulated void volume."
      }
    ],
    "result": "Darcy local rate (bbl/day) = 2.8175; Pore volume (m³) = 200",
    "interpretation": "Permeability changes flow capacity without changing the stipulated void volume.",
    "control": "Permeability (mD)",
    "columns": [
      "Permeability (mD)",
      "Darcy local rate (bbl/day)",
      "Pore volume (m³)"
    ],
    "rows": [
      [
        10,
        0.28175,
        200
      ],
      [
        25,
        0.7043749999999999,
        200
      ],
      [
        100,
        2.8174999999999994,
        200
      ],
      [
        250,
        7.04375,
        200
      ],
      [
        1000,
        28.175,
        200
      ]
    ],
    "baseline": 2,
    "rowNotes": [
      "Permeability (mD) = 10. Darcy local rate (bbl/day): 0.28175; Pore volume (m³): 200.",
      "Permeability (mD) = 25. Darcy local rate (bbl/day): 0.704375; Pore volume (m³): 200.",
      "Permeability (mD) = 100. Darcy local rate (bbl/day): 2.8175; Pore volume (m³): 200.",
      "Permeability (mD) = 250. Darcy local rate (bbl/day): 7.04375; Pore volume (m³): 200.",
      "Permeability (mD) = 1000. Darcy local rate (bbl/day): 28.175; Pore volume (m³): 200."
    ],
    "provenance": "Original synthetic teaching calculation. Equations and fixed controls are stated here; these are not field measurements.",
    "questions": [
      {
        "question": "Reproduce the baseline Darcy local rate (bbl/day) without rounding intermediate values.",
        "answer": "Vpore = 0.2 × 1,000 = 200 m³; at k = 100 mD, q = 0.001127 × 100 × 500 × 100/(2 × 1,000) = 2.8175 bbl/day. Darcy local rate (bbl/day) = 2.8175. Permeability changes flow capacity without changing the stipulated void volume."
      },
      {
        "question": "Compare the first and last recorded scenarios. Which input changes?",
        "answer": "Permeability (mD) changes from 10 to 1000. Other controls remain as stated in the premise. Darcy local rate (bbl/day) changes from 0.28175 to 28.175."
      },
      {
        "question": "What would be needed to apply this example to a different physical system?",
        "answer": "Replace the synthetic controls with compatible documented inputs and check the relation's assumptions. Pore volume is 200 m³ in every row; flow uses the published field-unit linear Darcy defaults except for k. Permeability changes flow capacity without changing the stipulated void volume."
      }
    ]
  },
  "recorded": null
}