Unconventional oil and gas
Unconventional petroleum and gas are produced or extracted from the soil using techniques other than conventional drilling methods. Oil sands, biomass-based liquid supplies, oil and gas shales and coalbed methane are some of the most common examples of unconventional reserves. The IEA estimates that at current production rates, global proven conventional and unconventional reserves add up to approximately 46 years of oil. According to the IEA, the volume of ultimately recoverable resources is estimated to be much larger than proven reserves.