We can’t go back in time. By now, shale champions like EOG Resources (NYSE: EOG) and Continental (NYSE: CLR) are household names, and they’ll never again be the winning lottery tickets they were when hardly anyone knew what fracking was and drilling leases were cheaper than dirt.

Mind you, they’re still cash machines: EOG has returned nearly 70 percent over the last 12 months, while Continental’s up 36 percent in that span. But even this is a far cry from the windfalls of investors who bought in when the companies were much smaller and not yet so obviously successful.

Which is not to say that any outfit with a line of credit and a drill bit is the next EOG or Continental; in fact let me stress that the company profiled below will never, ever get that big or rich. But it doesn’t need to in order to hit a home run for investors, given the modest current valuation and a clear path to accelerating production growth.

Small-cap oil & gas explorers are clearly high-risk propositions that can occasionally deliver outsized rewards. The key is to catch them soon after drilling results begin to show that the downside is modest. Emerald Oil (NYSE: EOX) could well be one of those, a fledgling Bakken operator starting to deliver unexpectedly robust recovery rates in the less developed southern half of North Dakota’s McKenzie County in the core of the Williston Basin.

The company, run by a former energy investment manager and banker, is in the early stages of a transformation as a non-operating investor in a number of regions to a pure-play Williston operator with 85,000 net acres harboring an estimated 435 potential drilling locations, enough to keep Emerald’s three current rigs busy for the next decade. The company has drilled just 15 wells to date, but so far they’re delivering very impressive production rates suggesting Emerald’s acreage remains undervalued, perhaps dramatically.

Production jumped 80 percent last year from a tiny base and is forecast to roughly double this year, except that management has already said it would be raising that guidance in early May once it can better estimate the positive recent trends.

Source: Company presentation

If Emerald can continue to execute on achievable growth plans and delivering strong well results the current enterprise value of 6 to 8 times this year’s likely EBITDA is going to look like a gift in a couple to years.

Of course, the usual caveats apply. Emerald has a very limited operating record, and is drilling in a harsh environment with notorious infrastructure constraints (though its current wells all have pipeline access.) And while the company has sufficient liquidity to fund its aggressive 2014 spending plans, it goes without saying that it’s drilling at this point with borrowed money as well as cash on hand from recent asset disposals, and will need more financing to bankroll the expected growth in 2015 and beyond.

The market cap is a modest $439 million, and this is a volatile, high-risk investment. Nevertheless the prospective rewards are both attractive and achievable. We added Emerald to the Aggressive Portfolio on March 18. Buy EOX below $7.50.