Discussion on Mechanical and Drilling Performance of the Positive Displacement Motors of Wall Thickness Rubber

The wall-thickness rubber stator positive displacement motors (PDM) has a long service life, high mechanical efficiency, and adaptability to bottom-hole temperature. With the increase of using time, the output torque of the drilling tool is stable, which can improve the crop of drilling and reduce fuel consumption. The uniform thickness of the rubber layer in the stator spiral cavity of equal wall thickness screw drilling tools, compared with that of the conventional positive displacement motors with the equal wall, the motor rotor swing offset is constant, the wear of the universal shaft is reduced, and the service reliability and life of the cardan shaft are improved. A mathematical model was used to simulate some of the mechanical properties of the positive displacement motors of wall-thickness rubber. The result shows that the wall-thickness rubber stator PDM has a high single-stage pressure, its length is about half shorter than the conventional PDM, and its output torque is basically the same, which can achieve the near bit effect of MWD or LWD, which is conducive to the application in medium and short radius deflecting, and the deflecting effect is obvious. The results of finite element analysis show that the wall-thickness rubber stator has better-sealing properties, more uniform stress distribution, and fewer stress changes than the conventional stator.