Arabian Journal for Science and Engineering https://doi.org/10.1007/s13369-019-04061-9 RESEARCH ARTICLE - MECHANICAL ENGINEERING Dynamic Research and Experimental Analysis of a New Downhole Drilling Tool Jialin Tian 1 · Lai Wei 1 · Tangjia Zhang 1 Received: 12 March 2019 / Accepted: 23 July 2019 © King Fahd University of Petroleum & Minerals 2019 Abstract With the increasing of drilling depth, the working conditions of the drilling engineering are becoming more complicated. When drilling in the complex well structure, there are many new problems or challenges such as low rate of penetration (ROP), serious stick–slip phenomenon, or high risk of downhole tools failure. The most critical factor in solving these new challenges is improving rock breaking efficiency. Considering this, this paper proposed a new oscillator based on the positive displacement motor. Combining with new complex drilling conditions, the new structure was designed. The mathematical models were presented, including the working mechanism of the new design with its structure parameters. Furthermore, the theoretical models of dynamics under new conditions were analyzed, including the new bottom hole assembly. Based on this, we can get the vibration displacement, velocity, and the system vibration spectrum at different drill string positions. Compared with the results of a numerical example, the lab test was carried out. The two important parameters of vibration frequency and impact forces were compared with the theoretical results, which verified the correctness of the theoretical model and the accuracy of the solution method. Moreover, field experiments were also tested to verify the results, and the field experimental data showed that the new design could increase ROP obviously. The method and conclusions of the research can provide a new reference for the new downhole technology of enhancing the ROP or improving the rock breaking efficiency in complex well structure. Keywords Vibration · Drilling · Dynamics · Downhole tool · Rate of penetration (ROP) · Rock breaking · Test analysis Abbreviations PDC Polycrystalline diamond compact ROP Rate of penetration WOB Weight on bit BHA Bottom hole assembly HWDP Heavy weight drill pipe B Jialin Tian tianjialin001@gmail.com; 309009838@qq.com B Lai Wei 1364845946@qq.com 1 Key Laboratory of Oil and Gas Equipment Ministry of Education, School of Mechanical Engineering, Southwest Petroleum University, Chengdu 610500, China 1 Introduction With the rapid development of the global economy, the demand for energy in the industry has been increasing. Oil and natural gas resources are still one of the indispensable important energy sources for today’s society [1]. However, there are still many problems to be solved in oil exploration and exploitation. For example, when drilling hard forma- tions, the problems of low drilling speed and low efficiency often appear, increasing economic costs. In order to solve these problems, Lubinski et al. [2] applied the theory of elas- tic stability to the drill string to provide a theoretical basis for the study of the dynamics of the drill string. In 1960, Finnie et al. conducted an experimental study on the vibration of the drill string, the axial force and torque of the upper part of the drill string were measured for the first time, and the natural frequency of the drill string without damping was determined [3]. In the 1980s, modern drill string dynamics began to form and deeper research on the vibration of the drill string began. Skaugen et al. [4] established the time domain drill string 123