Abstract:Tahe Oilfield is an important oil and gas production area in China, and lost circulation endangers production safety in the field. Lost circulation in Tahe Oilfield happens mostly in the Permian, Carboniferous and Ordovician strata. The causes can be summarized as below: well developed fractures in the Permian strata, highly sensitive Carboniferous strata and large crack-holes in the Ordovician strata. In this paper, the geological characteristics of Tahe Oilfield are summarized with the resulting down hole incidents such as lost circulation expounded and analyzed. At length, the technical methods for lost circulation prevention and plugging in Tahe Oilfield are summarized, providing some reference for the future exploitation in this region.