Optimal design method of vibration drag reduction parameters in horizontal well drilling

Horizontal well drilling is the mainstream well-type technology in developing various unconventional oil and gas resources. Field practice shows that installing a vibration drag reducer on the drill string can significantly reduce string friction, effectively alleviate frequent backing pressure in the process of drilling, and help to increase the rate of penetration (ROP). However, the current selection and use of drag reduction tools is still based on field experience and lacks effective theoretical method guidance. To this end, this paper establishes a dynamic model of drill string with vibration drag reduction tools, and reveals the drag reduction laws under different vibration drag reduction parameters. Then, based on the vibration propagation distance model and the inverse torque action distance model, an optimized design method of excitation parameters and installation parameters of vibration drag reduction tools is established by taking the improvement of drag reduction efficiency as the objective and the drill string fatigue failure and hydraulic energy loss as the constraints. The following research results are obtained. First, the excitation force amplitude, number and installation spacing of drag reducers are the main factors affecting drag reduction efficiency. Second, with the increase of excitation force amplitude and installation number of drag reducers, the drag reduction efficiency increases continuously. When the vibration propagation ranges of multiple drag reducers are independent, the drag reduction efficiency is higher than that when he vibration propagation ranges of multiple drag reducers are superimposed. Third, there is a risk of pipe string fatigue failure if the excitation force amplitude of the drag reducer is too large, and a risk of excessive hydraulic energy loss if too many drag reducers are installed. In conclusion, the drag reduction efficiency is increased to 40.1% from the original 10.2% after this method is applied to optimize the drag reducer. This method can provide an effective guidance for the optimization of excitation and installation parameters of drag reduction tools, support the reduction of drill string friction during sliding drilling of long horizontal wells, and significantly improve the ROP. © 2023 Natural Gas Industry Journal Agency. All rights reserved.