Characterization and mechanism of cutter parameters in tubing milling

Abstract

Downhole string milling is becoming increasingly difficult due to the increasing complexity of oilfield development technology and material quality advances, especially for downhole tubing milling. In this paper, a Lagrangian modeling approach is used to investigate the mechanism and effects of cutting parameters on tubing milling characteristics. The cemented carbide cutter parameters, including the cutting angle, lateral angle, weight on cutter, and rotating speed, are determined to obtain the maximum cutting rate. A cutting tool is designed, manufactured, and tested. The simulation results are in good agreement with the test results, yielding the maximum equivalent stress generated by the cutter of 1163 MPa, which is much higher compared to the tubing yield strength. The tubing cutting volume and mass increased with the cutting angle, up to 12.5°, while the maximum value obtained using the lateral angle is 5°. With an increase in weight on cutter, the maximum von Mises equivalent stress and equivalent strain generated by the cutter also increased. Furthermore, the cutting volume and mass increase rapidly with the rotational speed at the start, followed by a slow increase when the rotational speed is above 70 rpm. The cutter mainly generated continuous chips. Finally, industrial tests are successfully carried out, confirming the milling efficiency increase of 40.1% compared to the traditional milling methods.