Abstract
Transylvanian Basin is one of the most important natural gas basins in Continental Europe that marked the beginning of the development of the natural gas industry in Romania by the discovery of the first natural gas field in 1909 in Sarmasel (Mures County). The Basin of Transylvania is the geological unit with the largest and most natural gas reservoirs in Romania. It is the single sedimentation basin in Romania and among the few in the world where only gas accumulations, mainly methane, have been discovered, to which are added very small proportions (below 2%) of higher fractions (in the south-east area of the basin).