Guide to Shale Gas

Shale Gas vs Conventional Gas

Natural gas resources are typically divided into two categories: conventional and unconventional.

Conventional gas typically is found in reservoirs with permeabilities greater than 1 mD and can be extracted via traditional techniques. A large proportion of the gas produced globally to date is conventional, and is relatively easy and inexpensive to extract. In contrast, unconventional gas is found in reservoirs with relatively low permeabilities (less than 1 mD) and hence cannot be extracted via conventional methods.

There are several types of unconventional gas resources that are produced today but the three most common types are tight gas, coal bed methane and shale gas. Given the low permeability of these reservoirs, the gas must be developed via special techniques including fracture stimulation (or “fraccing”) in order to be produced commercially.