Design And Research On 105 Single Positive Displacement Motor For Workover Treatment

In order to cope with the relatively tough period of the oil and gas industry,measures have to be taken to reduce the cost on production,as well as increase the efficiency and safety of drilling.Therefore,people pay much attention to cost effective drilling and workover technology.Single positive displacement motor has been widely used owing to its multiple advantages.Endless problems come into being and workover treatments are always needed,after the field started production.In this thesis,a small size single positive displacement motor used for workover treatment are studied,which can reduce the cost on manufacturing.According to function,the single positive displacement motor can be divided into five parts which are bypass valve assembly,anti-falling joint assembly,screw motor assembly,cardan shaft assembly and transmission shaft assembly.Firstly,the single screw motor which performs core function is designed.Based on the optimization of meshing profile of screw liner,the structure parameters of the screw liner pair with a screw head ratio of 2:3 are calculated.Then,component selection and physical dimension design are performed for the bypass valve assembly,anti-falling joint assembly,cardan shaft assembly and transmission shaft assembly,successively.A set of parts and assembly drawing of the downhole machine unit are completed.By employing the finite element software ANSYS,the key components,transmission shaft and petal tooth of the cardan shaft,are checked and validated when the screw motor has the largest torque output.Combined with theoretical calculation,they are showed satisfying the operating requirements.The hydraulic characteristics curve of screw motor can provide a basis for selecting proper positive displacement motor for different working condition.In order to understand the hydraulic characteristics curve,the fluid model of the screw model is built and simplified.By using the finite element fluid element simulation software FLUENT,three external characteristics curves: rotational speed-torque,consumed power-torque,and efficiency-torque,were simulated under increasing flowrate.