Understand how EIA updates reshape Permian production data

The U.S. Energy Information Administration (EIA) recently refined how it measures shale oil and shale gas production in the Permian Basin, the most productive oil region in the United States.

These updates may sound technical, but they actually reveal important trends about how production is evolving across formations and why the Permian continues to dominate global energy supply.

Below are the most relevant takeaways from the March 2026 Short-Term Energy Outlook (STEO):

1. New shale formations added to Permian estimates

The EIA incorporated four additional fields into its shale production calculations:

• Avalon 

• Barnett 

• Dean (sometimes called Wolfberry) 

• Woodford

These formations join the already-tracked core Permian fields:

• Spraberry 

• Bone Spring 

• Wolfcamp

Together, these layers form a complex stacked geology that makes the Permian one of the most productive unconventional basins in the world.

2. Some formations were removed after geological review

At the same time, two formations were excluded:

• Delaware 

• Yeso-Glorieta

After reviewing geological data, the EIA determined these formations are conventional reservoirs, not shale or tight formations.

Removing them slightly reduced previous estimates of shale production, but the addition of new fields more than offset the change.

3. Updated estimates increase Permian shale output

The revisions resulted in a net increase in production estimates for 2025:

• +0.2 million barrels per day of shale oil 

• +0.8 billion cubic feet per day of shale gas

This highlights how better geological interpretation can change how production is measured, even if actual drilling activity remains the same.

4. The Permian remains the backbone of U.S. oil output

As of December 2025, Permian shale formations produced:

• 6 million barrels per day of crude oil 

• 22.2 billion cubic feet per day of dry natural gas

That represents:

• 44% of total U.S. oil production 

• 19% of total U.S. marketed gas production

Few regions in the world concentrate that much energy supply in one basin.

5. Three formations still dominate production

Despite the new additions, the Permian’s production continues to rely heavily on three core formations:

• Bone Spring 

• Spraberry 

• Wolfcamp

Combined production from these fields reaches:

• 5.7 million barrels per day of oil 

• 20.8 billion cubic feet per day of gas

These formations remain the foundation of the Permian’s massive output.

6. Smaller formations are growing rapidly

Although the newly added fields represent about 5% of total Permian production, their growth is notable:

Compared with 2022:

• Oil production has more than doubled (+0.2 million b/d) 

• Natural gas output is projected to grow 72% (+0.6 Bcf/d) by 2025

This growth reflects expanding drilling activity and improved reservoir understanding.

7. Why measurement methods matter

The EIA tracks production using two different approaches:

• By geological formation 

• By geographic region

Because formations overlap vertically like layers of a cake, these two methods produce slightly different totals.

For example, the Permian geographic region produced:

• 6.7 million barrels per day of oil 

• 29.1 billion cubic feet per day of marketed gas

—higher totals than formation-only estimates.

The Permian Basin is not just large, it is geologically complex and constantly evolving.

By refining how shale formations are classified, the EIA provides a clearer picture of where production growth is coming from and how unconventional resources continue to shape the global energy market.

Understand How EIA Updates Reshape Permian Production Data