{
  "version": 1,
  "topic": "WC06",
  "title": "SIDPP versus SICP what each pressure represents",
  "createdAt": "2026-10-24",
  "case": {
    "title": "Two paths to one static bottom pressure",
    "premise": "Bottom pressure fixed at 6,740 psig; drillpipe head 6,240 psi, so SIDPP = 500 psig. Annular head varies.",
    "formula": "SICP = 6,740 − annular head",
    "variables": "Both surface pressures are gauge readings on the same atmosphere; the columns connect to the same bottom datum.",
    "steps": [
      {
        "label": "Define the baseline",
        "calculation": "Annular head (psi) = 5800",
        "explanation": "Bottom pressure fixed at 6,740 psig; drillpipe head 6,240 psi, so SIDPP = 500 psig. Annular head varies."
      },
      {
        "label": "Select the relation",
        "calculation": "SICP = 6,740 − annular head",
        "explanation": "Both surface pressures are gauge readings on the same atmosphere; the columns connect to the same bottom datum."
      },
      {
        "label": "Substitute the values",
        "calculation": "6,740 − 5,800 = 940 psig; 6,740 − 6,240 = 500 psig",
        "explanation": "Retain intermediate precision. The displayed values are rounded only after evaluation."
      },
      {
        "label": "Read the result",
        "calculation": "SICP (psig) = 940; SIDPP (psig) = 500",
        "explanation": "Different surface readings can balance the same bottom pressure when fluid heads differ."
      }
    ],
    "result": "SICP (psig) = 940; SIDPP (psig) = 500",
    "interpretation": "Different surface readings can balance the same bottom pressure when fluid heads differ.",
    "control": "Annular head (psi)",
    "columns": [
      "Annular head (psi)",
      "SICP (psig)",
      "SIDPP (psig)"
    ],
    "rows": [
      [
        5400,
        1340,
        500
      ],
      [
        5600,
        1140,
        500
      ],
      [
        5800,
        940,
        500
      ],
      [
        6000,
        740,
        500
      ],
      [
        6240,
        500,
        500
      ]
    ],
    "baseline": 2,
    "rowNotes": [
      "Annular head (psi) = 5400. SICP (psig): 1340; SIDPP (psig): 500.",
      "Annular head (psi) = 5600. SICP (psig): 1140; SIDPP (psig): 500.",
      "Annular head (psi) = 5800. SICP (psig): 940; SIDPP (psig): 500.",
      "Annular head (psi) = 6000. SICP (psig): 740; SIDPP (psig): 500.",
      "Annular head (psi) = 6240. SICP (psig): 500; SIDPP (psig): 500."
    ],
    "provenance": "Original synthetic teaching calculation. Equations and fixed controls are stated here; these are not field measurements.",
    "questions": [
      {
        "question": "Reproduce the baseline SICP (psig) without rounding intermediate values.",
        "answer": "6,740 − 5,800 = 940 psig; 6,740 − 6,240 = 500 psig. SICP (psig) = 940. Different surface readings can balance the same bottom pressure when fluid heads differ."
      },
      {
        "question": "Compare the first and last recorded scenarios. Which input changes?",
        "answer": "Annular head (psi) changes from 5400 to 6240. Other controls remain as stated in the premise. SICP (psig) changes from 1340 to 500."
      },
      {
        "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. Both surface pressures are gauge readings on the same atmosphere; the columns connect to the same bottom datum. Different surface readings can balance the same bottom pressure when fluid heads differ."
      }
    ]
  },
  "recorded": null
}