I took a look at the Petrominerales 2008 Annual Report to see if I could come up with a number. PMG averaged about 11,000 barrels/day of light sweet crude in 2008 and its netback was $65.79. This was on an average oil price of $82.27. They have a pretty good future in terms of finding more oil in their extensive holdings, perhaps simialr to IOC.
They are a low cost/high netback producer but had to ship most of this oil by truck to a terminal (they are in Colombia). I think they set up as well as any E & P for this comparison on an apples to apples basis - 100% oil production, similar grade oil, low cost producer, barging costs=trucking costs, oil exploration futures equal, $82 oil price/$65 netback not too far off, etc.
At year end 2008 they had 99 MM shares outstanding (basic) and 108.6MM (diluted)
Their 50 week moving average at the end of 2008 looks to be about $11.90. So their average market cap was roughly 1.2B basic to 1.3B diluted. If we assume IOC can do 11,000 b/d and get the same market cap, the market cap would increase from $2.65 B (at $61.78 share) to $3.8B or $88.59/share.