Abstract: The various factors considered in the design process of well structure and casing string for extended reach well and concrete measurement adopted in engineering are presented.The engineering geology data of XJ24-1 Oilfield is presented.The main principles adopted in the design of well structure and the well structure practically adopted in the engineering practice are presented.The design results of casing string program are presented,which utilizes newly developed software for load analysis and strength design of casing string.These technology were validated by the successful extended reach drilling completion in XJ24-1 Oilfield.