What next for shareholders of last year's small-cap successes?

While many of the main market's larger constituents have experienced stellar rises in their share prices over the last year, their performance pales when compared to the gains enjoyed by the shareholders of some smaller companies. Let's look at two relative market minnows and ask whether this momentum can continue in 2017.

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World class assets

You only need to glance at the share price graph of £629m cap Hurricane Energy(LSE: HUR) over the last 12 months to understand why so many private investors are drawn to oil stocks, particularly those lower down the market spectrum. Priced at a fraction under 10p one year ago, shares in the Godalming-based explorer now trade at 53p thanks to a series of extremely positive updates from the company.

Back in September, Hurricane announced that it had found a 620 m oil column in its Lancaster well -- one of the biggest such discoveries in the North Sea. Then, only last month, the company revealed that its Lincoln project had discovered another significant column of 660 m. As a result, Hurricane stated that it would be revising the latter's pre-drill resource estimates of 250m barrels of recoverable oil. There is now speculation that Lincoln could generate double this figure.

In 2017, the company will be bringing Lancaster to development while also turning its attention to its "hugely important" Halifax asset -- a project with the potential to be as lucrative as the other two. Assuming that Hurricane is able to replicate their success (and eventually generate over 1bn barrels of resources), its share price could be a lot higher in a few years.

Permission to dig, sir?

Those who bought shares in £15m micro-cap potash and phosphate explorer, Harvest Minerals(LSE: HMI) at the start of 2016 would have seen a 230% rise to their holding. Like Hurricane Energy, I think there could be more to come.

Just before Christmas, the company announced it had received the trial permit for its Arapua fertiliser project in Brazil, enabling Harvest to commence mining before the end of December as intended. A few days later, it released a further update which emphasised the "consistent quality of the mineralisation at Maximus" -- part of the Arapua site.

After a brief rise, the shares have now settled back to just over 17p, largely because this news was expected. A more sustained increase could be on the cards in 2017 though. Independent consultants have been retained to revise the current resource -- an announcement on which is expected by mid-February. Meanwhile, Harvest will continue developing the market for its KP Fertil product. The fact that a letter of intent has already been signed with Veloso -- one of the largest coffee producers in the region -- bodes well. Executive Chairman, Brian McMaster has also commented on the company's desire to seek out "other projects which fit our criteria of being able to generate near term cash flows". Given what Harvest has achieved in 2016 on a limited budget, I regard this statement of intent as encouraging.

Make no mistake, Harvest Minerals remains a speculative play and one that is only likely to appeal to those who have sufficiently long investing horizons. Given that Brazil is the fifth largest consumer of fertiliser in the world and almost entirely dependent on importing it from abroad, however, I think the potential rewards may outweigh the risk.

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Paul Summers owns shares in Harvest Minerals. The Motley Fool UK has no position in any of the shares mentioned. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.