gempy

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3D structural geological modeling using implicit methods. Create geological models with faults, folds, and unconformities from surface points and orientations. Use when Claude needs to: (1) Build 3D geological models from surface contacts and orientations, (2) Model faults, unconformities, or intrusions, (3) Compute and visualize subsurface geology, (4) Export models to VTK or numpy arrays, (5) Generate gravity forward models, (6) Create cross-sections or 3D visualizations.

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Sourcesteadfastasart/geoscience-skills

Added on2026-05-16

NPX Install

npx skill4agent add steadfastasart/geoscience-skills gempy

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GemPy - 3D Geological Modelling

Quick Reference

python

import gempy as gp

# Create model
geo_model = gp.create_geomodel(
    project_name='Model',
    extent=[0, 1000, 0, 1000, 0, 500],  # [xmin, xmax, ymin, ymax, zmin, zmax]
    resolution=[50, 50, 25]
)

# Add surface points and orientations
gp.add_surface_points(geo_model, x=[100, 500, 900], y=[500, 500, 500],
                      z=[400, 350, 400], surface='TopFormation')
gp.add_orientations(geo_model, x=[500], y=[500], z=[375],
                    pole_vector=[0, 0, 1], surface='TopFormation')

# Compute and visualize
gp.set_interpolator(geo_model)
sol = gp.compute_model(geo_model)
gp.plot_2d(geo_model, cell_number=[25], direction='y')

Key Classes

Class	Purpose
`GeoModel`	Main container - holds all model data
`StructuralFrame`	Manages geological relationships
`Grid`	Computation mesh for interpolation
`Solutions`	Model results (lithology, scalar fields)

Essential Operations

Define Geological Relationships

python

gp.map_stack_to_surfaces(geo_model, mapping={
    'Strata1': ['TopFormation', 'BaseFormation'],
    'Basement': ['Basement']
})
geo_model.structural_frame.structural_groups[0].structural_relation = \
    gp.data.StackRelationType.ERODE

Add Faults

python

gp.add_surface_points(geo_model, x=[300, 300, 300], y=[200, 500, 800],
                      z=[100, 250, 400], surface='Fault1')
gp.add_orientations(geo_model, x=[300], y=[500], z=[250],
                    pole_vector=[1, 0, 0.5], surface='Fault1')
gp.map_stack_to_surfaces(geo_model, mapping={
    'Fault_Series': ['Fault1'],
    'Strata1': ['Layer1', 'Layer2'],
})
geo_model.structural_frame.structural_groups[0].structural_relation = \
    gp.data.StackRelationType.FAULT

Load Data from Files

python

import pandas as pd

points_df = pd.read_csv('surface_points.csv')  # Columns: X, Y, Z, surface
gp.add_surface_points(geo_model, x=points_df['X'], y=points_df['Y'],
                      z=points_df['Z'], surface=points_df['surface'])

ori_df = pd.read_csv('orientations.csv')  # Columns: X, Y, Z, dip, azimuth, surface
gp.add_orientations(geo_model, x=ori_df['X'], y=ori_df['Y'], z=ori_df['Z'],
                    dip=ori_df['dip'], azimuth=ori_df['azimuth'],
                    surface=ori_df['surface'])

Visualization

python

gp.plot_2d(geo_model, cell_number=[25], direction='y', show_data=True)
gp.plot_3d(geo_model, show_data=True, show_surfaces=True)  # Requires PyVista

Access Results

python

sol = gp.compute_model(geo_model)
lithology = sol.raw_arrays.lith_block
lith_3d = lithology.reshape(geo_model.grid.regular_grid.resolution)

Structural Relation Types

Type	Description
`ERODE`	Younger surface erodes older (unconformity)
`ONLAP`	Younger onlaps onto older
`FAULT`	Surface is a fault plane
`INTRUSION`	Intrusive body

When to Use vs Alternatives

Scenario	Recommendation
3D implicit geological modelling from surface data	GemPy - purpose-built, Python-native
Complex fold modelling with structural frames	LoopStructural - better fold support
Commercial-grade subsurface modelling	SKUA-GOCAD - industry standard, proprietary
Quick 2D cross-sections only	GemPy works but may be overkill; consider manual interpolation
Need gravity/magnetics forward model from geology	GemPy - has built-in potential field support

Choose GemPy when: You need implicit 3D geological modelling from surface contacts and orientations with fault/unconformity relationships, especially when integrated with Python workflows. It has a gentler learning curve than LoopStructural for standard cases.

Avoid GemPy when: Your geology is dominated by complex folding (use LoopStructural), or you need production-grade reservoir modelling (use commercial tools).

Common Workflows

Build 3D geological model from surface data

Load or define surface contact points (min 2 per surface) and orientations (min 1 per surface)
Create
```
GeoModel
```
with appropriate extent and resolution
Add surface points with
```
gp.add_surface_points()
```
Add orientations with
```
gp.add_orientations()
```
Map geological stack with
```
gp.map_stack_to_surfaces()
```
Set structural relations (ERODE, ONLAP, FAULT)
Set interpolator with
```
gp.set_interpolator()
```
Compute model with
```
gp.compute_model()
```
Validate with 2D cross-sections using
```
gp.plot_2d()
```
Visualize 3D result with
```
gp.plot_3d()
```
or export to VTK

Common Issues

Issue	Solution
Model not computing	Check min 2 points + 1 orientation per surface
Artifacts at edges	Extend model extent beyond data
Wrong fault offset	Check pole_vector direction
Memory errors	Reduce grid resolution

References

Structural Relations - Detailed guide on ERODE, ONLAP, FAULT
Data Requirements - Input data formats and constraints
Troubleshooting - Common problems and solutions

Scripts

scripts/validate_input.py - Validate input data files
scripts/export_model.py - Export model to VTK, numpy, or CSV

gempy

NPX Install

Tags

SKILL.md Content

GemPy - 3D Geological Modelling

Quick Reference

Key Classes

Essential Operations

Define Geological Relationships

Add Faults

Load Data from Files

Visualization

Access Results

Structural Relation Types

When to Use vs Alternatives

Common Workflows

Build 3D geological model from surface data

Common Issues

References

Scripts