Re P90 / 50 / 10 etc. What people have said above is basically...

Re P90 / 50 / 10 etc. What people have said above is basically correct but strictly it only applies to "reserves" in a field where oil has already been found and declared commercial. Companies are not permitted to classify their share of discoveries as "reserves" until there is a near certainty that the oil / gas will actually get produced. The P90 / 50 / 10 numbers are then the range of amounts that might utlimately get produced depending on the various factors already discussed (plus others like recovery factor).

Where it is too early to be sure that the discovered oil / gas will get produced (Banda would be a good case in point), companies sometimes use term like "scope for recovery" (SFR), meaning IF we were able to produce the reserves commercially, here's how much we think there might be. Shell very recently got itself into trouble and had to restate its reserves downwards by 20% because (amongst other things) they had classified hydrocarbons in "maybe one day if everything goes right" projects like Gorgon as "reserves" when they should never have been in that category to start with.

Where the oil / gas has not actually been discovered but is merely an enticing blip on a seismic chart, P90/50/10 are pretty meaningless concepts, because of course there is no guarantee that there are any producible hydrocarbons present. If a company applies the "P90/50/10" terminology to an undrilled prospect they are really just suggesting a guesstimated range of possible field sizes, but there are way too many unknowns for the "90/50/10" likelihoods to have any meaning at all. Those numbers certainly don't say anything whatsoever about the actual chance of oil / gas being present.

Sorry if all that is a bit of a lengthy dissertation but it's worth being clear about.

For Hardman's Mauritania finds, the oil in Chinguetti would be pretty safe to classify as reserves right now. Everything else would fall into the "SFR" bucket, but there would be a good chance of Tiof moving to reserves in a year or two after some more appraisal drilling and analysis. Banda looks longer term to me. It will be interesting to see whether Woodside classifies Chinguetti oil as reserves in its impending annual reserves statement, or whether they wait until the project gets the formal investment go ahead expected around mid-year.

On sushi's list of risks to the HDR valuation the only thing to keep in mind is oil price. Like any oiler, $/share values are very leveraged to the long term price of the black stuff. $1.40/share is pretty comfortable for Chinguetti + Tiof at current prices, but it would be a different story if prices fell back to the low $20s. So expect to see HDR's price fluctuating a bit more with oil price movements as the analysts and investment managers start putting more work into their valuations and linking them to their oil price forecasts.