Drag reduction performance of an axial oscillating tool with different kinds of waveform using a multiscale friction model

Abstract

Abstract Axial oscillating tools (AOT) are among the most widely used mechanical drag reduction technologies in the drilling field due to their environmental friendliness and ease of use. There are various waveforms of axial oscillating tools because of the differences in their structure and mechanism. However, only the sinusoidal wave is adopted to analyze the performance of axial oscillating tools. This paper widely investigated the types and applications of axial oscillating tools and summarized the idealized waveforms of these tools, which are sinusoidal, triangle, and trapezoid waveforms. To analyze the performance of these waveforms, a multiscale friction model was adopted based on the Dahl model according to the drilling environment. The model was verified using experimental data. The simulation results demonstrated that the magnitude of negative velocity could influence the performance of drag reduction. The greater the negative velocity, the better the performances of drag reduction achieved. For triangle and trapezoidal waves, the time ratio and magnitude of positive displacement in a period did not remarkably affect the performance of drag reduction for certain amplitudes and frequencies. According to the simulation results, when the time ratio of negative velocity was greater than (2/π)2, the drag reduction performance of the triangle and trapezoidal waveforms were better than that of the sinusoidal wave. These conclusions can be of benefit for the design of axial oscillating tools to obtain a more efficient performance of drag reduction.