The Research Of Rule On Drill String Vibration Of Horizontal Well

During the horizontal well drilling process, the drill string will producing various forms of vibration, its have three vibration forms mainly: axial vibration, lateral vibration and torsion vibration. Drastic vibration of the drill string will caused the drill string failure, and causing drilling accidents thereby, its influences drill security and will bring huge economic losses.According to the actual drilling situation in this paper, and the horizontal well drill string vibration mechanical model is established, make use of the finite element method for theory analysis. The three kinds of drill string vibration mode natural frequency formula has been get taken out combined with the drill string dynamics, drill string mechanics, mechanics and material mechanics.The model of horizontal well drilling string vibration is established according to the practical well bore data and bottom assemblies, and take advantage of the large finite element analysis software ANSYS. Then the modal analysis was carried out on the model, obtained respectively the natural frequency spectrum distribution to the vertical well section and horizontal well section of axial vibration, lateral vibration and torsion vibration. And found the frequency of drill string lateral vibration is relatively low through compared with the three kinds of vibration frequency, so it’s probable occur single or several drill pipe transverse resonance in the process of drilling, long hole drill string of drill string lateral vibration is difficultly to occur, this is consistent with the actual drilling situation. And three kinds of theoretical analysis of frequency of vibration and the finite element software to simulate frequency values are compared respectively, the error is smaller between them.On the basis of the modal analysis, the longitudinal vibration and the transverse vibration of harmonic response analysis was carried out on the horizontal section of the drill string, get the horizontal vibration dynamic response spectrum. The results showed that the response is strong for frequency and the modal analysis drill string vibration frequency is consistent. And found that the response frequency is nothing to do with the bit space exerting weight on bit,drill pressure increases, the peak value increases just. Using the response curve can futher illustrate, as long as the good control in the process of drilling speed, it can achieve the purpose of avoiding resonance effectively, in order to avoid the drill string resonance provides a theoretical basis.