@Article{cmes.2020.09236,
AUTHOR = {Min Luo, Tingting Xu, Jiajun Jiang, Xu Chi, Jing Wang, Shihua Xue},
TITLE = {Two-Layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in the Wellbore},
JOURNAL = {Computer Modeling in Engineering \& Sciences},
VOLUME = {123},
YEAR = {2020},
NUMBER = {1},
PAGES = {75--100},
URL = {http://www.techscience.com/CMES/v123n1/38485},
ISSN = {1526-1506},
ABSTRACT = {The lack of research on flexible drilling tool leads to limited application of
ultra-short radius horizontal wells. The flexible drilling tool is different from the 
conventional drilling tool. The flexible drilling pipe involves a mutual transition between 
the structure and the mechanism during the deformation process. At the same time, the 
flexible drilling pipe and the eccentric guide tube, the guide tube and the wellbore 
generate random contact. In this paper, 3-D beam elements, universal joint elements, 
rigid beam elements and the beam-beam contact elements are combined to establish a 
two-layer contact nonlinear finite element model of the flexible drilling tool in the 
wellbore. The dynamic relaxation method is introduced for numerical solution. The 
feasibility of the model and the algorithm is verified by an example. The mechanical 
analysis of flexible drilling tool under the four hole inclinations in the oblique section is 
carried out. It is found that the flexible drilling pipe has a “folded line” deformation. The 
contact force between the flexible drilling pipe and the guide tube is randomly distributed. 
The contact force between the guide tube and the wellbore in the oblique section is 
greater than that in the vertical section. As the hole inclinations increase, the torque and 
axial force transmitted to the drill bit gradually decrease.},
DOI = {10.32604/cmes.2020.09236}
}