Fabrication and Application of Drill String Dynamics Experiment Bench for Small-Scale Horizontal Wells

In the process of horizontal well drilling, the motion law of the drill bit and the drill string is very complex. The cost of studies by conducting site tests for the vibration of the drill bit and the drill string is high, which makes it difficult to accurately decouple various factors. In addition, the data sampling rate is low, hindering the systematic analysis. Therefore, based on physical similarity, a drill string dynamics simulation experiment bench for small-scale horizontal wells was designed on the basis of micro drill bit, drill string, and rock. The segmented casing was designed on the drill string to simulate the constraint of casing on the drill string. In order to more truly reflect the impact of the interaction between drill bit and rock on drill pipe and drill bit vibration, a micro polycrystalline diamond compact (PDC) bit was designed to simulate rock breaking. Laboratory experiments of drill strings in horizontal wells were carried out to study the effect law of coupling vibration, rotational speed, and weight on bit (WOB) on the vibration of the drill string system. The results show that the axial vibration of the drill bit has a great influence on the torsional vibration of the drill bit. When the drill string is under torsional vibration, the power spectral density of the drill bit is obviously higher than that under constant rotation. With the increase in the rotation speed, the transverse vibration acceleration of the drill bit and drill string also increases, and the vibration amplitude of the drill bit under torsional vibration within the main frequency increases. With the increase in WOB, stick-slip vibration and transverse vibration of the drill bit are intensified, but the axial vibration is not significantly affected.