Development and Application of Self-Excited Vortex Control Hydraulic Oscillator

An autonomous self-excited vortex control hydraulic oscillator has the advantage of having no degrading parts, a low manufacturing cost and small pressure drop, which can reduce the friction during drilling and thus reduce the possibility of getting stuck, thus optimizing WOB transmission and increasing the ROP. In order to solve the problem of high levels of friction during drilling of extended reach wells and long horizontal section horizontal wells, a self-excited vortex control hydraulic oscillator was developed, which consists of a steady-state jet element and a vortex variable liquid resistance zone. In principle, it mainly uses the Coanda effect of the jet and a specific flow path form to generate periodic vortex, so as to produce axial oscillations. By using a 2D numerical model, the flow state inside the self-excited vortex control hydraulic oscillator and the relationship between its performance parameters and the inlet flow rate were analyzed based the computational fluid dynamics method. The numerical simulation analysis shows that the main performance parameter of the oscillator, pressure pulsation amplitude, exhibits a square relationship with the inlet flow, and pressure pulsation frequency has a linear relationship with the inlet flow. Field applications show that the autonomous, self-triggering vortex control hydraulic oscillator can not only significantly improve the ROP, but also has no impact on MWD tools. It possesses the characteristics of simple structure, reliable function and excellent working performance.