Simulation Analysis And Design Of New Type Of Downhole Motor

Downhole motor is a kind of near-bit and power-driven tools which is Wide range of application, high efficiency and energy saving. They always be used in the geologic, coal and oil and gas drilling field. Among of them, the most representative tools are the turbine drill and the screw drill. While those two tools has some deficiencies. For example, because the diameter of turbine drills are always large and their torque are formed by fluid impacting kinetic energy, so turbine drills have soft mechanical properties. Namely, increasing torque can reduce the rotate speed and the anti-overload ability will also become weak, such is easy to produce brake. screw drills always have long length and hard mechanical properties compared to turbine drills. At the same time, the overload capacity is also strong. However, at work, the greater torque is, the lower rotate speed is. And when pressure differences exceed the limit, a sharp brake will happen. What’s more, the stator’s material is nitrile rubber, embrittlement is easy to occur after a long work. Such will impact screw drills’ life.In view of above problems and combined with the development of existing technology, this paper presents a work mechanism of multi-level multi-cavity positive displacement fluid transmitting pressure, then set up the multi-parallel-connected downhole motor system which take pressure difference between closed cavities as the driving force, and this is a very efficient mechanism which is the designing basis of a new type of downhole motor.In this article, three kinds of downhole motors—the ball plug type, the slider type and the cycloid type downhole motor. Ball plug type downhole motor applies to largemedium diameter drill series, whose acting medium is gas and liquid, flow mode is shaft type flow, and there is a pin rod connection between dynamic mechanism and shell. The slider type downhole motor applies to small and medium caliber series, the role of medium is liquid, the way to allocate flow is three layers axial flow. We use a key connection between dynamic mechanism and shell.Make the theoretical analysis and perform simulation on the designed downhole motor, and main of the theoretical analysis is to derive and calculate the theoretical working parameters of the two kinds of downhole motors with the ball plug type and the slider type, and determine theirs structural parameters and working ability. The result shows that the output torque of two downhole motors is proportional to the input of fluid pressure, the output speed is proportional to the input flow. In the simulation of this article, the first part is using ADAMS software to carry on the dynamics analysis of downhole motors with slipper type. We can get the information that the output speed of it has the characteristics of periodic intermittency. The second part is using LMS Virtual Lab Motion application software to analyze the movement condition and torque characteristics of single plunger of downhole motor with the ball plug type, and we can see from the analysis result is that the motor runs smoothly. The third part is using ANSYS software to check the output shaft of downhole motors with the ball plug type. The output shaft can meet the required strength when working.