Unconventional gas reservoirs include tight gas sands, shales, and coalbed methane. The key factor in these reservoirs is that stimulation treatments and/or horizontal well technologies are required to provide economic flow rates due to low formation permeability. In addition, tight sand and coalbed reservoirs are multi-layered, thus necessitating several stimulation treatments. Shales on the other hand, are often thicker formations, but can be multi-layered as well. In the past five years, horizontal wells have been used extensively in coalbed and shale reservoirs. Multiple stimulation treatments are often pumped in the horizontal shale wells.

From a production standpoint, tight sands produce from primary porosity and often from natural fractures. Shales add another storage and production component termed adsorbed gas. Adsorption occurs on the organic particles within the pore space. Coalbed reservoirs contain primarily organic material with some storage in the micro-porosity and cleat system, thus making it perhaps the most intriguing of all the unconventional targets. We hope you enjoy our website and the material it contains including several presentations and links to material that further discuss unconventional reservoirs.