welly - Well Data Analysis

Quick Reference

from welly import Well, Project

# Load single well
w = Well.from_las('well.las')

# Access data
df = w.df()                      # DataFrame
gr = w.data['GR']                # Curve object
values = gr.values               # numpy array
depth = gr.basis                 # depth array

# Well info
print(w.name, w.uwi)
print(w.data.keys())             # Available curves

# Load multiple wells
p = Project.from_las('wells/*.las')
for well in p:
    print(well.name)

Key Classes

Class	Purpose
Well	Single well with curves, location, tops
Project	Collection of wells for multi-well workflows
Curve	Log curve with depth basis, units, and processing methods

Essential Operations

Access Curve Data

gr = w.data['GR']
print(gr.mnemonic, gr.units)     # Metadata
print(gr.start, gr.stop, gr.step)  # Depth range

Process Curves

gr = w.data['GR']

# Clean and filter
gr_clean = gr.despike(window=5, z=2)
gr_smooth = gr.smooth(window=11)

# Transform
gr_norm = gr.normalize()         # 0-1 range
gr_resampled = gr.resample(step=0.5)
gr_clipped = gr.clip(top=1500, bottom=2000)

Work with Formation Tops

w.tops = {
    'TopFormationA': 1500.0,
    'TopFormationB': 1750.0,
}

for name, depth in w.tops.items():
    print(f"{name}: {depth} m")

Multi-Well Project

from welly import Project

p = Project.from_las('wells/*.las')
print(f"Loaded {len(p)} wells")

# Filter and analyze
for w in p:
    if 'GR' in w.data:
        print(f"{w.name}: GR mean={w.data['GR'].values.mean():.1f}")

Export Data

# To DataFrame
df = w.df()

# To LAS file
w.to_las('output.las')

# To CSV
df.to_csv('well_data.csv')

Common Curve Mnemonics

Mnemonic	Description	Units
GR	Gamma Ray	GAPI
NPHI	Neutron Porosity	v/v
RHOB	Bulk Density	g/cc
DT	Sonic	us/ft
RT/ILD	Deep Resistivity	ohm.m
CALI	Caliper	in

Tips

1. Use Project for multi-well workflows - easier than managing individual files
2. Check units - welly tracks units, ensure consistency
3. Despike before analysis - remove outliers with curve.despike()
4. Resample to common basis - use curve.resample() for cross-well comparison
5. welly extends lasio - all lasio functionality available

When to Use vs Alternatives

Tool	Best For
welly	Multi-well projects, curve processing, formation tops management
lasio	Low-level LAS file I/O, header manipulation, malformed files
petropy	Petrophysical calculations (Vsh, porosity, Sw, permeability)

Use welly when you need to manage wells as objects with curves, tops, and metadata -- especially for multi-well QC and cross-well analysis via Project.

Use lasio instead when you only need to read/write LAS files, handle malformed headers, or need fine control over LAS formatting.

Use petropy instead when your focus is formation evaluation calculations (shale volume, porosity, water saturation) rather than data management.

Common Workflows

Load and QC a multi-well project

- [ ] Load wells with `Project.from_las('wells/*.las')`
- [ ] Check well count and names: `len(p)`, iterate wells
- [ ] Verify required curves exist in each well (`'GR' in w.data`)
- [ ] Despike and clean noisy curves: `curve.despike()`
- [ ] Resample to common depth basis for cross-well comparison
- [ ] Compute summary statistics per well (mean, min, max)
- [ ] Export cleaned data to LAS or DataFrame

References

• Curve Processing - Despike, smooth, normalize, resample methods
• Project Workflows - Multi-well analysis patterns

Scripts

• scripts/well_qc.py - QC well data for gaps and issues
• scripts/project_stats.py - Compute project-level statistics