Gas from shale
Shale oil and gas are hydrocarbons contained within underground shale beds, a type of sedimentary rock laid down millions of years ago. This shale rock acts as the hydrocarbon source rock. Shales containing the right quantities of gas for extraction have a number of common properties such as being rich in organic material and being in an area of high heat and pressure which has allowed oil to be converted into gas.
The gas can be held in natural fractures, open pore spaces or absorbed into organic material. Shale rock doesn’t usually have the right permeability to allow significant flow of gas. Unlike drilling into a conventional reservoir where there is at least some flow of oil and gas immediately, an unconventional accumulation such as shale oil and gas, must be stimulated in some way before it will begin to flow.
Shale gas has been produced for many years from places with natural fractures but hydraulic fracturing allows the fractures to be extended and to stimulate the oil or gas either to begin or continue flowing.
Lifecycle of a shale gas well video