Casing drilling technology applied to surface interval of a well in the Ledong 22-1 Gas Field,Yinggehai Basin

The surface intervals of wells in the Ledong 22-1Gas Field,Yinggehai Basin,were drilled through unconsolidated gray clay,which will easily collapse and bury the well.In order to successfully run casing into the design depth,several times of wiper tripping are often required on site,which has significantly slowed down the operation.To solve this problem,the Weatherford′s casing drilling technology was applied to the development wells of the Ledong 22-1Gas Field.First,compared to the conventional drilling,this casing drilling technology was discussed in this field practice as well as the utilized technical measures and precautions in the drilling process.Then,descriptions were given for the drilling tools,main equipments,cementing technologies,and process flow adopted in drilling the surface interval of Well LD22-1-A2with339.7mm casing,as well as their application performance.This developed surface casing and offshore drilling technology not only overcomes the difficulty of smoothly running surface casing into the design depth due to loose seabed strata,but improves the wellhead stability.With this casing drilling technology applied to the surface interval of wells in the Ledong 22-1Gas Field,the safety of field operation is thus improved,the drilling cycle shortened,and the drilling cost reduced,which provides a good reference for similar oil and gas fields.