Study Of Hydraulic Oscillation’s Mechanism Of Drag Reduction Which Based On The Rotary Valve With Flow

Friction between drill string and borehole wall will lead to appear "sticking" phenomenon to exerting WOB and down hole accidents in horizontal drilling, the big hole curvature, long horizontal section, and in slim hole Wells, it will affect the drilling efficiency. Hydraulic oscillation which based on rotary valve with flow drag reduction technology can get the excitation frequency and vibration intensity. Then the static friction between the drill string and borehole wall is transformed into kinetic friction. It can significantly reduce the drill string drag, and improve the effect of drilling and has good prospects for development. In this paper, its working mechanism was studied, and some research results were obtained.This paper firstly determining the working principle of hydraulic oscillation included the rotary valve with flow + turbo + spring vibration reduction after researching structure and working mechanism of hydraulic oscillation. After analyzing the structure this paper study the mathematical modeling of he distribution valve pressure flow characteristic model, the drilling string axial vibration model and the mechanism of water hammer pressure model.Based on AMESet multidisciplinary collaborative simulation software, combined with the mathematical model which has been said above, this paper had established the system model of hydraulic oscillator and had carried on the simulation research using AMESim software on the basis of vibration model and flow valve of hydraulic oscillator. Then this paper analyzed the vibration force change rules based on vibration displacement, vibration frequency, and flow. It lays the theoretical foundation for hydraulic oscillation mechanism of drag reduction of experimental study.According to the simulation results, hydraulic oscillation including rotary valve,power section and oscillatory section were designed. The related main drill parameters were calculated and checked. Then this paper designed a simplified experiment device of the mechanism of drag reduction, and got some experimental study, and for the experiment device inlet pressure, outlet pressure, parameters such asvibration displacement and vibration frequency for testing and analysis.Experimental results showed that the oscillation frequency, amplitude and exciting force increases with the input flow, flow control range and frequency range is limited by valve structure, frequency within a increases, the drag reduction effect increases, different flow valve structure of hydraulic oscillator would be used in different working conditions. According to the result of the experiment and the simulation results of comparison and analysis, put forward to a optimized design scheme for the purpose of strengthening the drag reduction effect of hydraulic vibrator which satisfy the slim hole drilling and small flow. This study provided a valuable reference to further improve the structure design of hydraulic oscillator, the output characteristics and applicable scope of, and laid a foundation for further study of this type of hydraulic oscillator.