Reaming techniques for huge gypsums in Qiunan–1 Well

Qiunan–1 well is an important exploration well deployed by the Southwest Oilfield Company in the Qiunan No.1 high position of structures west of the eastern Qiulitag structural belt in the Kuche Depression of Tarim Basin. Huge gypsums developed in the Kumugeliemu Group of the Tertiary System below the well. So the casing running gets more difficult and the risk gets higher. In view of the construction difficulties in the huge gypsums, the UR800 reaming tools developed by the DBS Company are used to the fourth whole drilling section. This paper lays emphasis on the introduction of the constructing difficulties in long open hole reaming, the selection of reaming tools, the technical measures, and the reaming construction process. Eight times of reaming and one time of drifting are conducted in the well, with the reaming section reaching 1338 m. This enables the Company to create the highest record of reaming the longest well section, having the highest reaming efficiency, and using the drilling fluid with the highest density (2.25 g/cm3).