Abstract: In view of the difficult downhole packing of old casing deformation wells,series of packers with large expansion ratio used for downhole operation are developed to drill through the upper casing deformation shaft,as well as to pack the bottom shaft of larger size.Also a set of packing technologies for casing deformation wells are developed.Then the modification in acid treatment,testing,water sticking,water blocking,and separate zone production of oil reservoirs is realized.Therefore,the technological difficulties in packing the assigned bottom shaft with larger size are solved,although it is incapable of lowering the operation string caused by the upper casing deformation.So it is possible to carry out downhole operation in the casing wells of serious deformation.The potential of old wells is brought into full play.This is of great significance to the late stage of oilfield development.