Typically, reservoir
attributes are presented
as single "average" 
numbers when working toward a
Recoverable Reserves number.  This approach
fails to acknowledge the likely error in each of
the input parameters. Monte Carlo forces workers
to gather the range for each input parameter where data is
available, and to estimate 2 S.D. ranges for those where data is not
available.  The simplified example on this pages does not include the
risk elements impacting the likelihood of finding production at all. 
Yankee Resources can help with your project and prospect risk assessment.