Design And Research Of Ultra-high Pressure Valve For Oil And Gas Well Fracturing

Fracturing is the key technology to exploit shale gas reservoirs.The large caliber fracturing valve is the core component in the fracturing process,and its working reliability is related to the normal production and safety of the whole fracturing operation.Therefore,it is of great practical significance to improve the structure of ultra-high pressure valve for fracturing and to master the characteristics of solid-liquid two-phase flow in the valve.Based on the research experience of fracturing valves at home and abroad,combined with working conditions and related design standards,the main structure of the valve is designed.In order to effectively prevent sand from entering the valve chamber,the split type valve seat structure was designed and the working principle of the valve seat sealing was analyzed.The design scheme of the actuator was determined,and the frictions that the actuator needed to overcome in the opening and closing process were analyzed to provide the mechanical basis for the design of the reset spring.The design parameters of the reset spring in the actuator were optimized by using the fmincon function,and the installation height of the spring was reduced by 6.69% after optimization.The scheme of each sealing part is designed and its sealing performance is analyzed.Through innovation and improvement of valve structure,the reliability of valve is improved.The valve body is the main pressure bearing component.In order to solve the stress concentration phenomenon,the valve body was treated with autofrettage technology,and the optimal autofrettage pressure was determined to be 370 MPa.After the autofretening treatment,the maximum stress is transferred to the inner wall of the valve body,the stress value is reduced by 23%,the stress distribution of the valve body becomes more uniform,and the fatigue life is increased by 2.36 times.The tensile strength of the stem is analyzed,the maximum bearing capacity of the dangerous section of the stem is calculated,and the finite element strength of the stem is checked.The stability of the stem under pressure was analyzed,and the critical stress of the stem instability was calculated to be 645.38 MPa.The reliability of the valve is improved by finite element method.The solid-liquid two-phase flow in the valve is simulated by numerical method,and the flow resistance characteristics and internal flow characteristics of the valve under different working conditions are analyzed.The influence of changing the opening and fracturing fluid configuration parameters on the pressure field distribution,velocity field distribution and sand trajectory is analyzed.At the same time,the wear law of valve channel under different working conditions is analyzed.By analyzing the solid-liquid two-phase flow characteristics of the valve,it provides a theoretical basis for reducing valve vibration and valve wear.