Abstract: Addressing to geological tectonic characteristics and difficulties encountered with well drilling in Kelasu Piedmont Tectonic Zone of Tarim Oilfield，combined with the requirements for well late completion test，and development and production，the casing program of 6 layer casing-7 layer casing is designed and developed.Special-purposed casings with especially-designed size，steel grade and thread type are developed on the basis of the requirements under the casing program，and the analyses of the casing service conditions in the ultra deep and complex well and typical failure cases. The results from batch operations of the casings in more than 60 wells show that design of the said casing program is reasonable，and capable of meeting the requirements for exploration in Kelasu Piedmont Tectonic Zone. And the special-purposed casings as especially-designed and developed are also capable of safe and reliable operation.