In the curved interval of horizontal well,great frictional resistance can be imposed on the casing string and result in great bending stress due to the bending of the hole.

• 套管柱在水平井弯曲段随井眼弯曲产生较大的弯曲应力和受到较大的摩擦阻力，有可能产生强度破坏、密封失效、稳定性破坏而不能下入。