Geological names

Geological names identify the rock formation a well targets. These names come from Alberta's stratigraphic nomenclature—a standardized system for naming underground rock layers based on age, composition, and location.

How geological names work

A geological name typically consists of a formation name followed by a zone or member identifier. The format is FORMATION ZONE, where the zone code (letters, numbers, or both) identifies a specific interval within the formation.

Examples

• ELLERSLIE GG — Ellerslie formation, GG member (Lower Cretaceous sandstone)
• MCMURRAY T — McMurray formation, T zone (oil sands)
• MUSKEG E — Muskeg formation, E zone (Devonian evaporites)
• CARDIUM A — Cardium formation, A sand (Upper Cretaceous)
• VIKING VK — Viking formation, VK zone (Cretaceous gas sands)
• DUVERNAY SHL — Duvernay formation, shale (unconventional play)

Common zone codes

Zone codes follow patterns but aren't entirely standardized. Common conventions include:

• Single letters (A, B, C) — typically top-to-bottom subdivisions
• Double/triple letters (GG, FFF) — finer subdivisions within a member
• Alphanumeric (D-3A, 2A) — specific reservoir units, often in reef complexes
• Abbreviations (SHL, SS, LS) — rock type indicators (shale, sandstone, limestone)

Why this matters

The geological name tells you what kind of rock the well is producing from, which determines:

• Expected fluid type (oil, gas, bitumen)
• Reservoir quality and production rates
• Appropriate drilling and completion techniques
• Depth range and pressure regime

Further reading

• Alberta Geological Survey: McMurray Formation Report