Vol.123, No.1, 2020, pp.75-100, doi:10.32604/cmes.2020.09236
OPEN ACCESS
ARTICLE
Two-Layer Contact Nonlinear Mechanical Analysis of Flexible Drilling Tool in the Wellbore
• Min Luo1, Tingting Xu1, *, Jiajun Jiang2, Xu Chi3, Jing Wang4, Shihua Xue1
1 Mechanical Science and Engineering College, Northeast Petroleum University, Daqing, 163318, China.
2 Toutai Oilfield, Daqing Oil Field Co., Daqing, 163000, China.
3 Natural Gas Branch, the Third Group of Oil and Gas Processing, Daqing Oil Field Co., Daqing, 163453, China.
4 Mathematics and Statistics College, Northeast Petroleum University, Daqing, 163318, China.
* Corresponding Author: Tingting Xu. Email: 15246067500@163.com.
Received 25 November 2019; Accepted 07 January 2020; Issue published 01 April 2020
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.
Keywords
Flexible drilling tool, beam element, universal joint, contact nonlinear, finite element.