Production decline curves of three representative low permeability gas wells in the Piceance Basin are analyzed. These wells produce from theMancos "B", Mesaverde and Wasatch formations, respectively.

It was found that long term production in these wells could be approximated using linear flow equations. This observation leads to the development of a decline curve method for predicting rate-time behavior based only on one or two years of production data. The method is easy to applyand requires only data which is routinely reported to state oil and gas regulatory agencies. This type of data is public information and is readily available in most states.

The observed long-term linear flow behavior indicates that fracture lengths are much longer than would beexpected from hydraulic fracturing treatments. Possible explanations forthis behavior are discussed. The possibility of using short-term test data to define the long-term production decline curve is also discussed.

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