Study And Application Of Progressing Cavity Pump Performance

As a new artificial lift method,PCP has attracted more and more attention by the oil fields in the world for its unique advantages including low investment,simple structure,easy operation,remarkable energy saving effect and wide application. As the matter of fact,these advantages haven't been fully played due to the incompletion and immaturity of PCP product and the matching technology. In that case,the aim of this project is to improve the PCP's performance,to widen its application scale,to prolong the working life,and to improve the operating performance,and as the result,to realize the high efficiency lift. In order to hit the above targets,a modified numerical simulator of PCP performance has been made based on the study of PCP performance in actual working condition.This paper analyzes in detail the kinematics and dynamics characters of PCP, the principle of the influence on PCP's performance made by the structural parameters,operation parameters and working conditions through experiments. Study indicated that the above factors had great effect on PCP's performance. For example,the increment of operating rotating speed,working temperature and medium viscosity will increase the PCP's lift capacity as well as the excursion of rotor's structural parameter and stator's molded line will also have considerate effect on PCP's performance. Moreover,it is considered to be an effective way to improve PCP's performance by advancing the accuracy of stator's size.Based on the geometric and physical characteristics of PCP's stator, mechanical and thermal models are made, and numerical simulation of the coupled thermo-mechanical model is carried out in finite element method, by the simulation, the deformation principle of stator molded line in practical conditions is got. Study indicated that the normal displacement of stator's molded line could be expressed by a sine curve and the distribution curve appears to be a"M"shape for the conventional PCP, while stator's molded line of even thickness stator PCP can be described by a three-nomial Fouier series and the distribution curve appears to be a"W"shape. The normal displacement is linear with stress for both the conventional and even thickness stator PCP, whereas the displacements differ by several folds under the same stress. Even thickness stator has not only small displacement and relief, but also much flat in distribution. The highest temperature point of the conventional PCP is in the center of place in minor axis direction where the rubber is thickest, but the highest temperature point of even thickness stator is in the connection of the straight lines and the arcs, and temperature distribution of stator is even. As the result,the performance of even wall stator PCP is much better than the conventional one in deformation and thermal swelling, and even thickness stator PCP also have apparent advantages on improving the working performance and prolong the working life.In this paper,PCP adapting to bad lubricating property, hollow rotor PCP and even wall stator PCP were developed to improve the PCP's performance based on the analysis of PCP working performance. The experiments on site indicated that hollow rotor PCP could not only improve the performance,but also apply a set of matching techniques for PCP oil production technology. At the same time,And it was also approved that even thickness stator PCP has obvious advantages in improving the PCP's performance. PCP adapting to bad lubricating property can make the friction torque decreased and continuously run in the special medium have bad lubricating property. The experiments of PCP working in high temperature and pressure oil well indicated,swelling and thermal expansion of elastomer make cavities smaller and volumetric efficiency decreased. Based on the experiments and the effect principle, technological measurements are made to improve PCP's efficiency and save energy, and make PCP service for oilfield production very well.Based on the working performance of PCP, and the models of helical flow including velocity, flow rate and differential pressure, production optimization design and working condition diagnostic techniques of PCP are made, PCP system will become a economical and safety artificial lift method with high efficiency, good adaptability and long run-life.