LONDON -- There a few oil companies that can lay claim to potential oil resources of multibillion barrels. But none of them seem to generate as much investor excitement as Gulf Keystone Petroleum (LSE: GKP.L).

The shares peaked at more than 4 pounds earlier this year. They've since halved, although they are up 5% at 223 pence this morning, valuing the company at 1.95 billion pounds, following a resource upgrade ahead of today's annual general meeting.

The resource in question is the Shaikan discovery in Kurdistan, where independent consultants have upgraded the P90 oil in place from 8 billion to 12.4 billion barrels. Gulf Keystone said the upgrade was based on the data acquired since the last resource evaluation in November 2011, and is the fourth successive upward revision since the Shaikan discovery was announced in August 2009. It's worth noting that this report is oil in place, which means not all of it may be commercially exploitable, and Gulf Keystone's working interest in Shaikan is 75%.

Gulf Keystone added that this report completed the appraisal program for the Shaikan field, and it would now submit a declaration of commerciality to the Kurdistan regional government, followed by an appraisal report.

Gulf Keystone CEO John Gerstenlauer very modestly commented:

Sometimes people get complacent about our operational track record. This latest upgrade, which now includes results from the Shaikan discovery well and five appraisal wells, is a timely reminder about Gulf Keystone's stellar drilling performance in the Kurdistan Region of Iraq.

... We are still to explore the deeper Triassic and Permian horizons with the Shaikan-7 exploration well and account for the potential oil volumes in the Cretaceous to the north of the field.

This success is both a function of the field, which is a giant by any measure, and of the team we have in place, both on the ground and in the Company's offices, which is progressing the move from the appraisal phase to the large-scale staged 400,000 barrels of oil per day development.

Gulf Keystone undoubtedly has a lot of potential, but (publicly) overconfident CEOs and oil companies rarely seem to be a good combination.

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