The impact of stimulation on production decline type curves for CBM wells

Coalbed methane (CBM) is considered an unconventional gas resource produced from coal seams usually with low permeability at shallow depths. Analyzing the production performance in CBM reservoirs is challenging, especially at the early stage of the recovery. Most of the small producers in the Appalachian Basin cannot afford personnel or meet economical requirements involved in the use of the numerical simulator to evaluate CBM reservoirs. Production type curve are useful tool for predicting the performance of CBM reservoirs. A set of type curves have been previously developed for unstimulated vertical wells in CBM reservoirs. Most of the CBM wells drilled in the Appalachian Basin are stimulated. Therefore, it is important to study the impact of stimulation on CBM production type curves. The impact of stimulation on the type curves however, has not been studied.; This study concluded that the production type curves are not affected by stimulation. However, the stimulation has significant impact on peak gas rate. A new correlation among peak gas rate, skin factor and porosity was developed. The correlation was validated and it showed accurate results with an error less than 10%.