Research On Working Mechanism Of Negative Pressure Pulse Oscillator

With the development of the global economy and the continuous improvement of people's living standards,people's demand for oil and gas resources has also increased.At present,conventional oil and gas field development cannot meet people's demand for oil and gas,and the development direction of oil and gas will inevitably develop toward more complex strata.In the oil and gas exploration and development process of complex wells such as horizontal wells and large displacement wells,it is difficult to control the wellbore trajectory,low mechanical drilling speed,and drill string support,which will bring great problems to the drilling process.In order to solve the above problems,an oscillating impactor has emerged and can produce a good effect.In this paper,a new type of negative pressure pulse hydrodynamic oscillator tool is designed to reduce the frictional resistance of horizontal and large displacement wells.According to its working principle,the corresponding structural design,fluid analysis,mechanical analysis,kinematics analysis,dynamic analysis and fluid simulation research are carried out.The following is the main research content of this article.Combined with the current research status of impact oscillator,a new type of negative pressure pulse hydrodynamic oscillator is designed.According to the structural composition of the tool,the author designs and calculates the powertrain,analyzes the motion law of the screw motor and the valve shaft system,establishes the motion analysis model of the motor and valve shaft system,compares and analyzes the two valve port design schemes,and analyzes the stiffness of the damping assembly.According to the calculation of the example,the following conclusions can be drawn.Both the screw motor and the valve shaft system do periodic movements.The rotational frequency of the valve shaft system is proportional to the flow rate of the input fluid.The outflow area of the valve shaft system increases as the diameter of the radial nozzle increases.As the number of layers of the disc spring stack increases,the rigidity of the disc spring system continues to decrease.The kinematics analysis results were used to analyze the hydraulic characteristics of the negative pressure pulse hydrodynamic oscillator.The impact force generated by the negative pressure pulse hydraulic oscillator is obtained by calculating the working pressure dropd and fluid water hammer characteristics of the fluid inside the valve shaft system.Combined with the relevant example parameters,the results of the working pressure drop,fluid water pressure and axial impact force of the negative pressure pulse hydrodynamic oscillator are obtained.Through the result analysis,it is concluded that when the fluid flow rate of the input tool is constant,the radial nozzle diameter of the valve shaft system is larger,the generated water hammer pressure are greater so the axial force impact force generated is larger.Simulate the flow state of the fluid inside the tool using ANSYS Fluent simulation software.Analyze the velocity and pressure distribution of the fluid inside the tool when the valve outlet flow area is different.And analyze the change of the pressure of the fluid inside the tool as the diameter of the nozzle changes.Finally,the accuracy and rationality of the theoretical calculation results are verified based on the fluid simulation results.Establish a dynamic analysis model of the negative pressure pulse hydraulic oscillator tool in the horizontal well,and analyze the influence of the axial vibration generated by the tool on the vibration effect of the drill string system.Combined with the relevant example parameters,the radial nozzle diameter,installation position and input flow of the negative pressure pulse hydrodynamic oscillator are analyzed to influence the vibration effect of the horizontal well drill string.According to the analysis results of the example,it can be known that the larger the diameter of the radial nozzle is,the more obvious the vibration effect of the tool is,and the better the drag reduction effect is.The closer the tool is installed to the drill bit,the worse the vibration effect of the drill string in the analysis section.The greater the fluid flow rate of the input tool,the greater the frequency of vibration generated by the tool.However,in the actual application of the drilling,the influence of the pressure drop and vibration of the tool on the measurement while drilling tool should be considered to select a reasonable radial nozzle diameter and installation position.In this paper,based on the structural principle of the negative pressure pulse hydrodynamic oscillator,a kinematic analysis model and a mechanical analysis model are established.Establish a vibration dynamics model of the negative pressure pulse hydrodynamic oscillator in the horizontal well section and analyze its vibration effect.Verify the accuracy of theoretical calculations by finite element fluid simulation analysis results.It provides a theoretical basis for the future field application selection and drilling speed increase of the negative pressure pulse hydrodynamic oscillator tool.