Santos Ltd (ASX: STO) shares are outpacing the benchmark today.

Shares in the S&P/ASX 200 Index (ASX: XJO) energy stock closed yesterday trading for $6.97. In early afternoon trade on Wednesday, shares are changing hands for $7.03 apiece, up 0.8%.

For some context, the ASX 200 is up 0.3% at this same time.

That's today's price action for you.

Now, if you're buying Santos shares, you'll want to know about this latest update from the ASX 200 oil and gas stock.

Santos shares encompass 1.559 billion barrels of oil equivalent

In its annual reserve update, unlikely to have a material impact on Santos shares today but important longer-term, the company revealed that its proved plus probable (2P) reserves stood at 1.559 billion barrels of oil equivalent (mmboe) at the end of 2024.

That's down a slender 15 mmboe year on year before production of 87 mmboe.

Santos noted that additions across several of its assets increased organic reserves by 15 mmboe. However, its 2P reserves were impacted by the 30 mmboe reduction following the sale of a 2.6% interest in PNG LNG to Kumul Petroleum.

The company reported that its three-year 2P reserves replacement ratio was 58%.

As for where Santos' oil and gas projects are located, the company said 41% of its total 2P reserves are held in international assets.

The total 2P reserves are comprised of 84% gas and 16% liquids.

Santos shares often come under scrutiny from environmentalists concerned over the impacts of its greenhouse gas contributions.

On that front, Santos reported that it continues to hold a 2P CO2 storage capacity of 9 million tonnes. 2C (best estimate of contingent resources) contingent storage resources increased by 47 million tonnes in 2024 to 178 million tonnes in the Cooper Basin.

What did management say?

Commenting on Santos' global reserves, CEO Kevin Gallagher said:

Today's statement is the result of Santos' disciplined annual reserves review and accounting processes, which include external audit of approximately 97% of total 2P reserves.

It's also pleasing to add another 47 million tonnes of 2C CO2 storage, which is an important asset to underpin Santos' decarbonisation strategy and commercial expansion of the successful Moomba CCS project to meet customer demand for CO2 storage in the future.

How have Santos shares been tracking?

Pressured in part by lacklustre oil prices, Santos shares are down around 4% over the past year.

Of course, that doesn't include the 45.9 cents in unfranked dividends Santos paid out over the year.

If we add those back in, the accumulated value of Santos shares is up 2.0% in 12 months.