Santos Ltd (ASX: STO) shares are storming higher today.

Shares in the S&P/ASX 200 Index (ASX: XJO) energy stock closed yesterday trading for $6.71. In early afternoon trade on Friday, shares are changing hands for $6.96 apiece, up 3.7%.

For some context, the ASX 200 is down 0.2% at this same time.

Today's outperformance is being driven by a big uplift in global oil prices.

Indeed, the Brent crude oil price is up 8.0% in 24 hours to US$74.90 per barrel. This sees the Brent crude oil price up 24.4% since 5 May, when that same barrel was worth US$60.20.

The downturn on the ASX and upswing for Santos shares and the oil price follow news that Israel has launched airstrikes against Iran's nuclear facilities. Investors are now bracing for potential retaliation.

That's the latest price action for you.

Now, getting back to our headline question, if you'd bought $10,000 worth of Santos shares five years ago, how much would you have today?

How have Santos shares fared over five years?

Five years ago, Santos shares had already come roaring back from their pandemic market crash lows.

But with the oil price still down at US$39 per barrel at the time, you could have picked up shares in the ASX 200 oil and gas company for $5.40 apiece.

Meaning you could have picked up 1,851 shares for $10,000, with enough change left over for a can of Coke.

At the current share price, that investment would be worth (a rounded) $12,883 today.

But let's not forget Santos' dividends.

If you'd bought Santos shares five years ago, and held onto them through to today, you'd have been eligible to receive the past 10 Santos dividends, some fully franked, the more recent ones not franked at all.

All told those 10 dividends add up to $1.38 a share.

Assuming you spent that passive income as it came in rather than reinvesting it, then adding those payouts back in to the current Santos share price of $6.96, we see that the accumulated value of the shares you bought for $5.40 in June 2020 is now worth $8.34.

That's a gain of 54.4%, or slightly ahead of the 46.1% five-year gains posted by the ASX 200.

And it means that your $10,000 investment in Santos shares on 12 June 2020 would have returned $15,437 by now.

Now what?

Santos shares closed up 2.9% on 17 April, the day the company released its March quarter results and reaffirmed its full-year guidance.

The ASX 200 energy stock expects to produce 90 to 97 million barrels of oil equivalent (mmboe), with sales volumes of 92 to 99 mmboe. Unit production costs are forecast to come in the range of US$7.00 to US$7.50 per barrel of oil equivalent.

"The business remains strong and resilient, maintaining free cash flow from operations breakeven oil price less than US$35 per barrel in 2025," Santos CEO Kevin Gallagher said on the day.