Abstract

Coal gas plays usually progress from rank wildcat wells, through multi-well pilot stage, then sometimes on to commercial production. Coalbed methane plays differ from conventional gas plays in that the time consuming and costly middle step of pilot testing is crucial to determination of commercial viability. Consequently, pilot tests have been conducted in several U.S. coal basins over the past 30 years. To increase pilot interpretability and reduce time and cost of future pilots, a review of past pilot tests in selected coal basins is presented. Pilot parameters such as the number of wells, well spacing, completions, and production life as well as characteristics of the target coal deposits are considered. The definition of dimensionless time from conventional gas reservoir engineering led to an equation for the minimum production time required for a given pilot to experience interference.