Dynamic Simulation And Optimal Design Of Pumping System With Staged Pumping Assistance

The production of low-permeability oil reservoirs in China is still generally used to produce oil with rod pumps.Since the fluid production index of low-permeability oil wells has dropped significantly after water breakthrough,the oil well can only be improved by continuously increasing the pumping depth and increasing the production pressure difference.Therefore,the development of low-permeability oilfields is geared toward deep pumping,high gas-liquid ratio,and high-efficiency lifting.After the pumping depth is deepened,the crude oil is easy to degas,the gas-liquid ratio is high,the stroke loss of the rod string is large,and the leakage is large,resulting in low system efficiency.In response to the development problems caused by deep pumping and high gas-to-liquid ratio oilfields,Sinopec Shengli Oilfield has proposed a new type of high-efficiency rod pumping systemgraded assisted pumping system.The grading assisted pumping system can achieve gasliquid mixed pumping,reduce the stroke loss of the rod string,thereby improving the pump efficiency,but like other oil extraction methods with rod pumps,when the pumping parameters of the oil well are not compatible with the working characteristics of the pump or the rod string characteristics,The pumping system is prone to failure and low work efficiency.Therefore,it is necessary to carry out dynamic simulation of the graded pumping aid system to optimize the pumping parameters of the graded pumping aid system.The main research content of this article includes the following aspects:The structure of the pumping aid and pressure reducing valve of the hierarchical pumping aid system is introduced,and its working principle is analyzed.A simulation model of the liquid pressure change law of each node in the wellbore is established,and the liquid in the pump under the coupling action of the pressure reducing valve and the pumping pump is established.Simulation model of pressure change law;comprehensively consider the influence of pump load,suspension point displacement,rod fluid friction,and pumping device load on the longitudinal vibration of the rod string under the coupling action of the pressure reducing valve and the oil well pump,and establish the assisted pumping device,reducing The longitudinal vibration simulation model of the rod string affected by the pressure valve;the dynamic parameter simulation model of the suspended point load,the crankshaft net torque,and the motor input and output power is established.Based on this,the Matlab software is used to simulate the dynamic parameters of different pumping systems.Imitated the pump indicator diagrams,suspended point indicator diagrams,and the actual plunger displacement versus time curve of different pumping systems,and analyzed and evaluated the application effects of the graded pumping-assisted pumping system;completed the pumping-assisted device and decompression The sensitivity analysis of valve-related structural parameters,oil well parameters,and swabbing parameters to displacement coefficients,and based on this,determine the design variables,objective functions,and constraints.The enumeration method is used to optimize the system with maximum system efficiency.Reasonable parameters enable it to meet the actual production requirements of oil wells while achieving the goal of economical and reasonable oilfield exploitation.