Design and Drilling of Well Mashen 1

Well Mashen 1 is an ultra-deep well drilled in the Sichuan Basin. Drilling of the well was characterized by difficulties in borehole quality control,ROP enhancement,coexistence of lost circulation and blowout,maintenance of desirable performances of drilling fluids and cement slurries,and quality control in cementing operations. Under such circumstances,a casing program involving conductor plus five spud-in intervals had been designed on the basis of specific features and risks of target formations,together with safety of drilling operations,quality,efficiencies,economic performances and other factors. According to the design,KCl polyamine sulfonation anti-sloughing drilling fluid and latex anti-gas channeling cement slurry system were to be used. In practice,gas drilling,foam drilling,"PDM drill plus PDC bit"composite drilling techniques,"turbo drill plus diamond-impregnated bit","RSS plus PDC bit" and other techniques had been deployed to enhance ROP. Drilling processes of the well were satisfactory with significant enhancement in ROPs. Generally speaking,the engineering design for the Well Mashen 1 was rational and all techniques adopted were satisfactory and could effectively remove drilling technical challenges.