It is a city in Bacau County, Moldova, Romania, made up of Poieni, Targu Ocna (residence) and Valcele. The locality belongs to the generation of feudal cities in Moldova, chronologically belonging to the subgeneration of the complementary urban settlements from XVI-XVIII centuries. He received the trade mark in 1721, the name being composed of the rank and occupation of the inhabitants. The town of Tirgu Ocna is housed in a depression bay in three parts of the Nemire Mountains in S and SV, Berzuntiului V in the mountains and subcarpathian hills in N. The mountain relief is represented by mountains and marshes, with altitudes falling from V to E. The minimum altitude of 250 m and is found in the E part of the city, in the Trotus meadow, and the maximum 320 m, At the foot of Mount Magura, to the valley of Slanic. Part N-E of the city belongs to the sub-Carpathian area consisting of young formations. This area is marked by two distinct elements: the depression gulf (Trotus aisle) and the sub-Carpathian hills. The area with a complex geological structure is characterized by a variety of subsoil resources: salt and potassium salts, petroleum, mineral springs, construction materials, etc. The oil and natural gas fields are cemented in the Kliwa sandstone from the external area of the fleece: Pacuri, Mosoare (Poieni), Beleleu.