Unconventional gas plays are often risky. To help understand the uncertainty inherent in these plays, probabilistic estimated ultimate recoveries (EUR's) can be employed. Once sufficient production data are available for a given play, production based probabilistic EUR's can be constructed.
Meaningful economics require introduction of a time component to such probabilistic EUR's. This study does so in two ways. First, detailed production data are used to construct probabilistic distributions for annual gas volumes. Secondly, probabilistic gas price distributions are constructed from pertinent histories. Distributions of gas volumes and prices are then coupled in Monte Carlo simulations to generate probabilistic economics. Examples are presented using production data from Raton coal gas and the Whiskey Buttes (Frontier Formation, low permeability gas field) in conjunction with Henry Hub and CIG price distributions.