CSV file containing depth and log curves:

• Required curves:

  • Depth: True vertical depth (TVD) used as reference for all calculations.

  • DT (compressional slowness): Primary input used in the Eaton model to estimate pore pressure.

  • Gamma Ray (GR): Used to identify shale intervals for compaction trend estimation.

  • Format: The first row must contain the column (log) names. Columns can be in any order; the user selects the corresponding logs within the app. Click here to download a test data set. 

• Optional curves:
  • Additional curve that can be used to further constrain shale selection. The shale definition becomes a combination of GR and the selected log condition.​​
  • Calibration gradient: Optional gradient curve that can be displayed in the gradient track for comparison with modeled results.

Eaton pressure model:

• Exponent n: Controls sensitivity of pore pressure to deviations from the compaction trend.  Typical values range from 2 to 4.

• Overburden pressure gradient (Sv): Used to compute pressure from depth. Default values are around ~1.0 psi/ft. The app does not require a specific unit system, but all inputs must be internally consistent.

• Hydrostatic gradient (Ph):  Freshwater: ~0.433 psi/ft. Brine: ~0.45–0.47 psi/ft.

• The app does not require a specific unit system; however, all inputs must be internally consistent. Use our app for units conversion if needed. 

Shale Filtering: Defines which data points are considered shale for NCT estimation.

• GR Cutoff: Identifies shale (e.g., GR > 75 API).

• Other Log Filter: Optional secondary filter (e.g., caliper, density).

• Smoothing (pts): Number of data points used to smooth the shale DT curve.

Normal Compaction Trend (NCT): Defines expected DT behavior under normal compaction.

• Mode:

  • Auto: Estimated from shale intervals within the selected depth range and Gamma Ray cutoff.

  • Manual: User defines slope and intercept

• CT Top / CT Bottom: Depth interval used to compute the trend

• CT Slope / CT Intercept: Linear trend parameters. Automatically generated slope and intercept can be modified when switched to manual mode. ​

Calibration & Display:

• Number of Calibration Points: Allows up to 5 depth-pressure pairs used to anchor modeled pressure.

• Units (Pressure / Gradient): Defines how calibration values are entered:

  • Pressure → user inputs pore pressure (Pp)

  • Gradient → user inputs pressure gradient

• Enforce DT ≥ NCT: Prevents unrealistic compaction behavior by ensuring the shale DT is greater than the normal compaction trend.