Experiment on the Influence of Drill String Damping and Pressurization Device on Bottom Hole Wob(Weight on Bit) Fluctuation

Large amplitude and high frequency WOB fluctuation will lead to problems such as low rock breaking efficiency, short service life and slow drilling speed. This problem is particularly prominent in hard and difficult to drill formation and multi interlayer formation. The development of drilling string damping and pressurization device provides an idea for the utilization of vibration energy. Theoretically, the installation of drill string damping and pressurization device can ensure the smooth operation of the bit. However, up to now, the influence of the characteristic parameters and application methods of drill string damping and pressurization device on the WOB fluctuation at the bit is not clear. Based on the drill string dynamics experimental device, the influence of drill string damping and pressurization device on WOB fluctuation at the bit is tested and analyzed. The results show that whether the drill string vibration damping and pressurization device can stabilize the bit WOB is related to its elastic stiffness, installation position, bit speed and WOB; When the WOB remains unchanged, the elastic stiffness of the elastic element of the drill string damping and pressurization device increases, and the fluctuation range of the WOB at the bit increases; Increasing the rotating speed and increasing the WOB is conducive to controlling the WOB fluctuation of the bit. Under the condition of high rotating speed, shortening the distance between the drill string damping and pressurization device and the bit is conducive to restraining the WOB fluctuation. The research results provide a reference for the design, development and application of damping elements of drilling string damping and pressurization device.