Biharkeresztes natural gas field is located in east-Hungary, by the Romanian border. Natural gas was first found in the metamorphic rocks and was then detected in lower-Pannonian beds. The sequence at Biharkeresztes consists of Precambrian metamorphite, , Miocene fine-grained sandstone and Pannonian deposits of Paratethys. The reservoir rock is fine-grained, light-grey sandstone, varying from 0.2 to several metres in thickness. The overlying bed is siltstone. The reservoir contains many small gas lenses.