1D mechanical earth model, built from the logs you already have
Turn sonic and density curves into a calibrated wellbore stability answer: elastic properties, overburden, pore pressure, rock strength, horizontal stresses, and the safe mud weight window, computed in your browser, on well data that never leaves your machine.
Geomechanics runs as its own workspace inside Formation Evaluation, on the same log viewer as the rest of your interpretation, so it reads the same LAS and DLIS curves, depth reference, zones, and unit system. Every parameter, calibration point, and zone override is saved with the case and restored with it. Outputs are written back as depth curves you can plot in the log viewer, overlay against calibration points, and export with the case.
Geomechanics is part of Formation Evaluation and is included from the Professional plan. Projects save to a folder on your computer and do not count toward cloud saved-case limits. See pricing
Geomechanics on RRS-1 EAGLE, 7,800–8,800 ft at a 0.5 ft sample rate, 2,001 mud-window samples. The shaded corridor is the safe window: floored by pore pressure and collapse, capped by the minimum horizontal stress. A synthetic well, so nothing here is client data.
What the model produces
Every output is a continuous curve along the wellbore, computed sample by sample from your input logs:
Shear slowness (DTS): measured, or synthesized with Castagna mudrock or Greenberg–Castagna where no shear log exists, including the gaps in a measured one
Dynamic and static elastic properties: Poisson's ratio and Young's modulus, with a configurable dynamic-to-static factor
Overburden stress (Sv): density integrated from the mudline, with water depth, air gap, and a linear ramp or Traugott power-law fill for the unlogged section
Pore pressure: Eaton (sonic or resistivity) or Bowers, including unloading, with normal compaction trends fitted on shale samples only
Rock strength: unconfined compressive strength by a correlation chosen per zone or picked automatically from mineral volumes, internal friction angle, and tensile strength as a fraction of UCS
Horizontal stresses: poroelastic Shmin and SHmax with tectonic strain terms, and the Eaton fracture gradient
Mud weight window: collapse and breakdown limits, then an operational window with kick, swab, and surge margins, in ppg, SG, or kPa/m
Uncertainty band: P10 to P90 window limits from a parameter Monte Carlo, with the parameter that drives the width named
Sanding onset: critical bottomhole flowing pressure (CBHFP) with the poroelastic wall term, for completion and drawdown screening
Brittleness: Rickman elastic index from the model's static Young's modulus and Poisson's ratio, and a mineralogical index from multimineral solver volumes with kerogen counted as ductile
Published methods, named in the interface
Nothing is a black box. You pick the correlation, you see the parameters, and the reference is on screen:
Pore pressure: Eaton (sonic), Eaton (resistivity), and Bowers with optional unloading behaviour, each calibrated to measured pressures
Shear synthesis: Castagna mudrock and Greenberg–Castagna by lithology (sandstone, limestone, dolomite, shale)
Rock strength: McNally for sandstone, Horsrud for shale, Golubev & Rabinovich for carbonate, and Lal for friction angle
Stress state: poroelastic horizontal stress with tectonic strains, Kirsch hoop stresses with a Mohr–Coulomb or Mogi–Coulomb collapse criterion and a tolerated breakout width, tensile breakdown, and the Eaton fracture gradient
Brittleness: Rickman (2008) elastic, and Jarvie (2007) or Wang and Gale (2009) mineralogical
Pore pressure methods in the workspace
Eaton (sonic)
Eaton (resistivity)
Bowers (sonic)
UCS correlations in the workspace
McNally: sandstone (Δt)
Horsrud: shale (Vp)
Golubev & Rabinovich: carbonate (Δt)
Calibrate against real measurements
A model that has not been calibrated is a guess. Import RFT/MDT formation pressure points as CSV, type them in, or reuse the ones already in Pressure Analysis, and fit the Eaton exponent, or the Bowers loading curve, to them with one click. Add leak-off tests in ppg EMW and fit the tectonic strain so the modelled Shmin, and with it the window ceiling, honours them; a formation integrity test that did not leak off is treated as a floor on Shmin, not a measurement. Fit the sonic or resistivity normal compaction trend on your own shale samples instead of accepting a default. Every point is drawn on the tracks against the curve it calibrates, and the fit reports the misfit before and after.
Deviated and horizontal wells
Vertical-well shortcuts break down as soon as the well builds angle. Switch the wellbore to deviated and the far-field stress tensor is rotated into borehole coordinates using inclination, well azimuth, and SHmax azimuth (per-sample survey data overrides the constants where you have it), so the mud weight window reflects the trajectory you are actually drilling. True vertical depth comes from the directional survey whatever the log is displaying, so a deviated well's overburden and hydrostatic column are right without any manual conversion.
Stress polygon
At any depth you choose, the Zoback stress polygon shows which stress regimes are frictionally admissible for your overburden, pore pressure, and friction coefficient, with your computed Shmin and SHmax plotted inside it. It is the fastest way to sanity-check whether a stress model is physically possible before anyone drills on it.
Your well data stays on your machine
Geomechanics inherits the Formation Evaluation local-first model. Logs, cases, and computed curves live in a project folder you choose on your computer through the browser File System Access API. We do not store well log files or interpretation cases in our database, and the geomechanics computation itself runs entirely in your browser.
Where teams use it
Well planning and mud weight design
Build the pre-drill mud weight window from offset well logs, then narrow it as calibration points arrive.
Wellbore stability review
Explain breakouts and losses after the fact by comparing the drilled mud weight against modelled collapse and breakdown pressures.
Completion and sanding risk
Screen drawdown limits with the sanding CBHFP curve before committing to a completion design.
Overpressure detection
Track pore pressure against the normal compaction trend to see where a section departs from hydrostatic.
How it fits your interpretation
1.Load LAS or DLIS logs into Formation Evaluation and set the depth reference and units
2.Open Compute → Geomechanics (1D MEM) and map DTC, DTS, RHOB, and resistivity curves
3.Choose the pore pressure method and fit the normal compaction trend on your shale samples
4.Import RFT/MDT and LOT/FIT calibration points and fit the Eaton exponent and tectonic strain to them
5.Set the failure criterion, breakout tolerance, and drilling margins, then review the mud weight window, its uncertainty band, and the stress polygon
6.Apply to write the curves back to the well in your chosen units, with the model saved on the case
Geomechanics questions
Do I need a shear sonic log to run a mechanical earth model?
No. If a DTS curve is present it is used directly. Where it is missing, over the whole well or only over the samples the shear tool did not log, shear slowness is synthesized from compressional slowness using the Castagna mudrock relation or Greenberg–Castagna with a lithology you select (sandstone, limestone, dolomite, or shale, for the well or per zone), and the synthesized curve is labelled as such so nobody mistakes it for a measurement.
Which pore pressure prediction methods are supported?
Eaton from sonic, Eaton from resistivity, and Bowers from sonic with optional unloading for exhumed or unloaded sections. Normal compaction trends can be fitted to your own shale intervals rather than left at library defaults, the Eaton exponent or the Bowers loading curve can be fitted to imported RFT/MDT points, and the predicted pressure is overlaid against them.
Does the mud weight window account for well deviation?
Yes. In deviated mode the far-field stress tensor is rotated into borehole coordinates using well inclination, well azimuth, and SHmax azimuth, with per-sample survey data taking precedence over constant values. Collapse and breakdown pressures are then solved around the inclined borehole rather than assuming a vertical well.
How is rock strength estimated?
Unconfined compressive strength comes from a log correlation you choose: McNally for sandstone, Horsrud for shale, or Golubev & Rabinovich for carbonate. Choose it for the well, override it per zone, or let the workspace pick it sample by sample from the probabilistic solver's mineral volumes. Internal friction angle is either a constant you set or derived from compressional velocity using Lal, and tensile strength is taken as a configurable fraction of UCS.
How is the mud weight window turned into something a driller can use?
The physical limits are the shear collapse pressure, by Mohr–Coulomb or Mogi–Coulomb with a breakout width you are willing to tolerate, and the tensile breakdown pressure, alongside the Eaton fracture gradient. The operational window then adds your kick, swab, and surge margins, and an optional Monte Carlo on the model parameters draws a P10 to P90 band around it so the narrow sections are obvious. Everything can be shown in ppg, SG, or kPa/m.
Is geomechanics a separate product or part of the platform?
It is a compute mode inside the Formation Evaluation workspace, included from the Professional plan as part of Formation Evaluation. There is no separate geomechanics licence, and results share the same case file, unit system, and export path as your petrophysical interpretation.
Does my well data get uploaded to run the model?
No. The geomechanics computation runs in your browser and the project folder lives on your computer. Well log files and interpretation cases are not stored in our database, and every log format, DLIS included, is parsed in the browser.
Geomechanics is one of the compute modes inside Formation Evaluation, alongside multimineral solving, permeability estimation, saturation-height modelling, pressure analysis, and synthetic seismograms.
