In Western Canada at the turn of the century, most gas discoveries are less than 10 106m3 (~3 bcf) in volume and the question has evolved from the simple "At what rate will it flow?" to the complex "How long will it remain commercial?". As a result, reserves measurement and production forecasting have become an integral part of the initial production test. In the planning and fieldwork stages, it is fortunate that a few simple adjustments to accepted testing techniques are all that are required to yield good reserves numbers. In the analysis stage, it has become apparent that pressure responses can be categorized to yield expected production profiles. Some production forecasts depend as much on the profile to be commercial as they do on the reserves. With respect to "rules of thumb", there have grown up some quick formulas for estimating reserves numbers and for forecasting the results of stimulations. The concept of skin factor has metamorphosed in the latter process.