oil price and valuation impact

As an example of how big a valaution impact current brent prices will have on ROCs underlying value I thought I would look at the RBS broker report. Given they are intitiating coverage I thought I would choose them as they would take a reasonable approach
RBS comment that they value roc at 55 as is and approx 68 if they execute Beibu as planned
Lets forget the additional 13 cents of execution value and focus on the 55 current core producing assets value
The following is the valaution impact of 2012 ave oil prices ( btw the terminology is theirs
Bear case - oil 85 usd - roc value 51 cents ( 64 with development success)
Base case oil 94.5 usd roc value 55 ( 68 wih development success)
Bull base oil 100 usd roc value 57( 70 cents with development success)
So from the above for every 4 dollars more averaged real oil price ROCs value increases by 2 cent. So using the above if we assume Brent averages 115 ( currently 120) core productive assets are worth about 61 cents and when adds in Beibu success it goes to 74 cents. On top of that we have the value of Balai cluster project which brokers are not adding much value until details are released but all say could add significant value. He one broker that does add value for balai values roc at 67 with an oil price assumption of 105.
In summary - current spot would suggest ROCs current value somewhere in the mid 70/s with only development success and no exploration success