Development status and prospect of hydro-oscillation drag reduction drilling technology

As horizontal wells and extended reach wells are widely applied to oil and gas production, the resistance drag between the drill string and the borehole wall in the process of drilling is higher, leading to the occurrence of backing pressure. As a result, the weight on bit cannot be exerted effectively, the rate of penetration (ROP) is impacted and even downhole accidents are induced, e.g. pipe clogging, sucking or sticking. The hydro-oscillation drag reduction technology makes use of the hydro-oscillator to generate the vibration with a certain frequency and amplitude along the axial direction of the drilling tool to transform the static friction into the dynamic friction, so as to reduce the resistance drag between the drilling tool and the borehole wall. Its development prospect is promising. The domestic and foreign research status on hydro-oscillators was analyzed systematically from the aspects of the principles of vibrating drag reduction, the typical structures of domestic and foreign hydro-oscillators and the key technologies. Then, the problems of existing hydro-oscillators were pointed out. Finally, the suggestions on developing the turbine driven hydro-oscillator were proposed. The research results can provide the reference and basis for the development and improvement of the hydro-oscillation drag reduction technology.