Research and development of anti-wear torque reducing tool with high-strength protective rubber sleeve

Existing anti-wear torque reducing tools are poorer in sliding friction property with short service life. To solve this problem, a new anti-wear torque reducing tool for well drilling was developed with high-strength rubber and metal-ceramic coating as the sliding friction pair. In normal temperature, high-strength rubber has tension strength 39 MPa, tearing strength 120 kN/mm and wear loss 0.003 cm³/1.61 km, and it, with the steel shaft whose external surface is coated with metal-ceramic constitutes the sliding friction pair. In the environment with bentonite mud as the circulation medium, the measured friction factor is only 0.068. After 2% quartz sand with grain size of 1 mm is added, the measured friction factor is 0.2, which is much lower than steel-steel friction factor (0.35-0.5). 28 sets of prototype tools were prepared and tested in an extended reach well with horizontal displacement about 3 000 m. It is shown that the torque is decreased by over 20% on average and its property is obviously superior to similar products. After the 28 sets of tools were taken out of wells, their sliding friction pairs only suffer slight scratching. The service life of each set of tool is over 1 000 h. Therefore, its popularization and application is of better value.