What does Petrophysical Evaluation calculate?
Petrophysical Evaluation runs formation evaluation for a well in one guided model, with tabs for environment, shale volume, porosity, water saturation, permeability, matrix, QC and results. It calculates shale volume, porosity (typed as total or effective according to the shale correction applied), water saturation, permeability and mineral volumes, then summarises net reservoir, net pay, average porosity and saturation, and hydrocarbon pore volume by zone. Deterministic mode produces one interpretation case. Stochastic mode runs 100, 500 or 1,000 Monte Carlo realisations through the whole chain, so shale-volume uncertainty carries through to permeability, and writes P10, P50 and P90 curves.
Can g-Space process multiple wells?
Yes. The individual calculators, including shale volume, porosity, saturation, permeability, mineral volume, base and elastic properties, pore pressure, UCS, horizontal stress, fluid substitution, lithology interpretation, electrofacies, environmental corrections and ML log prediction, have a batch mode that runs over all wells or a saved well filter or folder, each well over its own interval. Petrophysical Evaluation works on one well at a time: save its configuration as a run or a workflow step and reopen it on the next well.
Can petrophysical workflows be saved and reused?
Yes. Most wizards on the Petrophysics bar have Save to workflow, which stores the job with its full parameter set: well or batch scope, method, input curves, constants, zones and depth range. Opening the step reopens the wizard exactly as it was saved. Petrophysical Evaluation can also save a run per well. Re-running is a deliberate action: when an upstream input changes, downstream results are flagged as stale and wait for you to recalculate, rather than being recomputed silently. For several tools you can also right-click a calculated curve in the Data Manager to reopen the settings that produced it.
Does g-Space support machine-learning log prediction?
Yes. ML Log Prediction trains a CatBoost gradient-boosted decision-tree model on wells that carry both the selected predictor curves and the target log, and reports MAE, RMSE and prediction correlation together with a cross-correlation matrix of the inputs. The trained model is saved with the project and can be applied to one well or a batch of wells to write the predicted curve. It is a supervised prediction tool for missing or unavailable logs, not a general-purpose AI interpreter.
What geomechanical properties can be calculated?
Base properties gives hydrostatic pressure, formation temperature, vertical (overburden) stress and effective stress. Pore pressure offers Eaton (sonic), Bowers, sonic porosity, Traugott resistivity ratio and overburden minus effective stress methods. Elastic properties calculates Vs, Vp/Vs, acoustic and shear impedance, Young's, shear and bulk moduli, Poisson's ratio, Lamé's first parameter, P-wave modulus, Lambda-Rho and Mu-Rho. UCS provides eight correlations including a user-defined one, and Horizontal stress estimates Shmin and SHmax with six methods, bounded by frictional equilibrium. The Mohr diagram then shows the stress state against a Mohr-Coulomb friction envelope, and the Wellbore stability view turns the stresses, pore pressure and UCS into breakout width, collapse and breakdown pressure and the mud-weight window for every drilling direction.
Does g-Space support fluid substitution?
Yes. Fluid substitution applies isotropic, low-frequency Gassmann fluid substitution with Wood fluid mixing: the rock frame, porosity and shear modulus stay unchanged while the pore fluid is replaced. From acoustic, density and porosity logs plus mineral and fluid properties it writes substituted P-wave velocity, S-wave velocity, density, acoustic impedance, shear impedance and Vp/Vs, and can also output dry and saturated bulk moduli, fluid moduli and densities, and Poisson's ratio.
Which well-log formats can be imported?
LAS 1.2 and LAS 2.0 files, through Load LAS files or the Log Loading Wizard, and delimited text files (tab, space or comma separated) with a chosen header row and start row, where depth, value, mnemonic and unit columns are bound against a preview before import. Depth type, depth units and datum are set for each import.
Can g-Space evaluate wellbore stability?
Yes. The Wellbore stability view computes Kirsch borehole-wall stresses with a Mohr-Coulomb criterion from Sv, SHmax, Shmin, pore pressure and UCS, each taken from a well curve or typed as a value, at a reference depth you can move along the well. A polar disc over drilling direction is coloured by breakout width, collapse pressure, breakdown pressure or the safe mud-weight window, with the actual and a planned well trajectory drawn on it, and a companion cross-section shows the stresses around the hole in a chosen direction.
Does g-Space support FMI and borehole image data?
Yes. Borehole image data loads from LAS or DLIS array channels and displays as an image track beside conventional logs, with static, dynamic or manual normalisation and depth-dependent azimuth calibration. Bedding, fractures and breakouts can be picked as sinusoids, or dips can be found with automatic dip detection. Dips appear as a tadpole track, on a stereonet with a rose diagram and in a fracture-count track, and breakout picks give a mean breakout azimuth.
Can I use NMR logs in petrophysical interpretation?
Yes. NMR T2 distributions load as array channels and display as a track on a physical T2 axis alongside conventional well logs. NMR T2 interpretation applies a T2 cutoff to derive NMR porosity, bound fluid (BVI), free fluid (FFI), the T2 log-mean and SDR and Coates permeability, and the Permeability calculator also offers Coates and SDR methods.
Can core data be matched to well logs?
Yes. The Depth tie view aligns core data to the well-depth framework by core run, with a constant depth shift, with anchors that stretch and squeeze the intervals between them, or with Auto shift, which correlates the core curve against a selected reference log to find the best constant shift. Original core depths and values are preserved, and calibrated log curves are saved as a new run. Core tables, curves and images can be imported for one well or across many wells, core measurements display as points beside the logs, and core plugs and capillary-pressure data feed permeability calibration and the Saturation Height Model.
Can g-Space build a saturation-height model from core data?
Yes. The Saturation Height Model takes capillary-pressure measurements from a core table, with the plugs filtered by well, zone, test method and QC flag and the laboratory and reservoir fluid systems defined, then fits Brooks-Corey, Thomeer or Leverett-J to them and reports the fit quality per plug. Fitted coefficients can be correlated by zone group against porosity or permeability. The model is saved with the project and applied from a free-water level or fluid contact to write height above free water level, capillary pressure and water saturation curves back to the well.
How are logs cleaned and edited before interpretation?
Environmental Corrections first corrects gamma ray, density, neutron and resistivity logs for borehole effects, writing new traceable curves beside the originals. Edit LAS curve then applies moving-average, median or bandpass filters, depth shifts, expressions and normalisation to a reference well using percentile anchors, over an interval set by depth or markers, with every action in an undoable history. It opens from the Petrophysics bar or directly from the well correlation view by dragging over a curve, and on saving you choose whether to overwrite the original or keep it beside a new curve.
