| Exploration and exploitation are the important part of energy production.With the increase of our country's dependence on energy,drilling technology needs to be continuously improved.Mud pump is an important tool of drilling equipment,which greatly improves the drilling efficiency.Pistons are the most vulnerable parts of a mud pump.When the piston sealing performance is reduced,the high pressure sand particles will be involved in the friction pair movement wear,causing the piston to fail quickly.This will not only lead to downtime to replace the piston and thus affect the speed of drilling and wear the cylinder liner together,may also lead to serious collapse of the well wall and other accidents,resulting in huge losses of economy and property.Therefore,increasing the sealing performance of the mud pump piston is critical to the innovation of drilling technology and the improvement of industry productivity.This paper designs a striped high sealability mud pump piston based on the idea of non-smooth and multistage seal by analyzing the working principle and the stress situation of the mud pump piston.Taking the BW-160 type mud pump piston as the experimental object,9 sets of parameters of piston surface were designed,two experimental factors were selected,including the depth of the stripe and the angle between the stripe and the piston side.Based on the demand of experimental study on sealing performance of mud pump piston,a mud pump piston dynamic seal test bench was built,the test bench mainly aims at the purpose of friction test,sealing performance test and contact observation.The friction test and sealing performance test on striped BW-160 mud pump pistons were both executed on the test bed,life test was also carried out of the best piston in the test results.In the friction test,the friction of the piston with the strip depth 2mm,the angle 90 ° is minimal,the friction reduction effect is 53.89% higher than the standard piston,the influence of the angle of the stripe on the friction is greater than the influence of the depth of the stripe.In the sealing performance test,the piston with the strip depth 2mm,the angle 90 ° leaks the least,its sealing performance is 90.79% higher than that of the standard piston.Under the same conditions,the life test of the best piston and the standard piston were carried out,the results show that the life of the best piston is 114.58% higher than that of the standard piston.In order to reveal the stress and strain of the mud pump piston,the numerical simulation of mud pump piston under normal working conditions was carried out by means of reverse engineering and Workbench finite element analysis.The numerical simulation results show that the stripe structure can optimize the strain state of the piston,reduce the strain concentration on the interior,root and lip of the piston,improve the overall performance of the piston.The stripe structure can optimize the friction of the piston surface,disperse the friction force to the edge of the stripes,and reduce the abrasion of the lip.The stripes can prevent the piston root from being damaged by decreasing the Equivalent stress value of the piston root,it can also enhance the lip seal performance by increasing the contact pressure of the piston lip.The piston achieves the effect of multistage seal by increasing the contact pressure at the stripe structure.The initial leakage of BW-160 type mud pump piston is simulated,compared with standard piston,the stripe structure can store the leaked mud and reduce the leakage velocity.Through the transparent cylinder liner,the contact observation and image acquisition were carried out on the mud pump piston performance test bench.It shows that the stripe structure can store grease and deformation,increase the piston and cylinder sealing contact area,also form lubricating film on cylinder liner to improve friction performance,so as to enhance the sealing performance of the piston and achieve the purpose of reducing the seal failure. |
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