Concerns have been raised in many countries about the safety of fracking, a technique in which high-pressure fluids are pumped into shale to fracture the rock and force out natural gas.

Shale traps gas more tightly than other rock. To extract it, the shale is blasted with huge volumes of fresh water at high pressure, a practice known as hydraulic fracturing, or "fracking".

Attenuation of wave amplitude of reservoir rock at simulated high temperature and pressure is measured with spectrum-amplitude comparison mediod in laboratory.