ResFrac Part 4 modules

Ch. 23 geomechanics from logs, §20.4 sensitivity postprocessing, §20.3 stochastic parameter-group Monte Carlo, and benchmark comparison problems (SPE1, SPE10, corner-point ↔ rectilinear).

Units — applies to chart axes & exports

Active: Field · psi · ft

Edge-case validation — extreme μ / T / ρ

Export filename — organise runs by well & scenario

Well nameScenarioAppend timestamp (YYYYMMDD-HHMMSS)

Preview: geomech_csv_20260428-204920-field.csv

Export presets — one-click for this tab

Share last export — link works on any device until it expires

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No export yet — run a preset above and the file becomes shareable.

σh,min methodσv0 [MPa — SI input]pp grad [MPa/m — SI input]

§23.1 Pore-pressure builder

pp method

Hydrostatic gradient — no additional inputs.

Eaton uses local resistivity / Δt vs the normal-trend baseline (R_norm or Δt_norm) and falls back to pp_normal when the observed value matches the trend. Bowers inverts σ_eff = A·Vpᴮ from the Vp log; set Vp_max>0 and U>0 to engage the unloading branch. The resulting pp(z) feeds every σh,min method above.

§23.5.6 / §23.6.2 / §23.7 — frictional clamp · Δtₙ(z) decay · kv/kh

μ (friction, 0=off)?ω = kv/kh (0=off)?Δtₙ(z) decay?Enable §23.6.2 form

μ>0 enables the Mohr-Coulomb frictional-equilibrium lower bound on σh,min (Eq. 23-28). Δtₙ(z) decay replaces the constant Δt_norm in Eaton-sonic with Δt_m + (Δt_ml − Δt_m)·e^−c·z (Eq. 23-31). ω = kv/kh derives a vertical permeability column k_v = ω·k_h (Eq. 23-32). Disable any input (set to 0 or uncheck) to revert that physics to the §23 default.

σh,min FE bound & clamp — what this means

sigmaHminFE is the Mohr-Coulomb frictional-equilibrium lower bound: the smallest σh,min that a cohesion-less fault at friction μ can sustain without slipping (Eq. 23-28). It is computed at every depth from σv and pp.
feClampApplied is true on rows where the chosen σh,min model returned a value below sigmaHminFE, so the export reports the FE bound instead. It is always false when μ=0 (clamp disabled).
Practical reading: a high clamp rate means your stress model is predicting frictionally unstable σh,min — either the inputs (ν, K₀, εtect) are off, or μ is unrealistically high for the formation.

FE clamp inactive — set μ>0 above to enforce the Mohr-Coulomb lower bound.

§23.2 σv integral builder — σv(z) = σv0 + ∫ ρ(z′)·g dz′

Drive σh,min from custom ρ(z)

Density table — depth [m] / ρ [kg/m³] (always SI — physics input)

Trapezoidal integration preview

Depth [ft]	σv [psi]	Δσv [psi]
4921	4786.24	—
6562	6510.82	1724.58
8202	8278.07	1767.25
9843	10091.55	1813.48
11483	11940.58	1849.03

Trapezoidal integral of bulk density: σv0 anchors the surface stress; each Δσv contribution is ρ̄·g·Δz with g = 9.80665 m/s². Toggle the checkbox to feed this ρ(z) into every σh,min method (the orange dashed overlay shows the standalone σv preview either way).

Stress profile vs depth