Model for calculating pull-back force for pipe-laying in directional drilling

The stress state of in-hole pipe is very complicated in pipe-laying in directional drilling, and pull-back force is the main clue when choosing the drilling rig. Therefore, stress state analysis and calculation of pull-back force play significant role in directional crossing pipe-laying. By analyzing stress state of pipe in both flexure and steady division, the force model is established. And eventually, the actual case verified that this calculation method was more actual and more accurate.