Application of large size casing cementing technology about deep wells in Tarim Oilfield

Well KES2-1-14 is a key development well for natural gas located on Crassus belt of Kuqa depression of Tarim Basin and drilled well depth of 5 541 m. The well had complex geological structure. The Quaternary, Neogene and Paleogene section on Suweiyi Formation is a section of mudstone which is susceptive to swelling and collapse when contacted with water. There are also conglomerate and sandstone layers, which are low pressure leaking formations. In view of the formation characteristics and engineering Status, the ?365.13 mm + ?339.7 mm large size combination casing was used for 2nd spud and was run in to a depth of 5 541 m; Meanwhile, a low-viscosity lead drilling fluid, viscosity weighted spacer and separable setting cement slurry were used to finish cementing of large size casing in this deep well with large wellbore annulus. Electric log showed very good cementation quality. The casing setting depth in this well is 5 541 m, its bare weight is 617 t and cumulative injected and displaced volume is 1 167.6 m3, which are three new records in cement job at home.