Optimization Design Method of Excitation Parameters and Installation Parameters of Downhole Vibration Drag-Reduction Tools

Abstract

ABSTRACT: In the sliding steerable drilling operation in long horizontal wells, vibration drag-reduction tools can greatly reduce tubular drag, effectively alleviate frequent pipe sticking problem and improve rate of penetration. The excitation parameters and installation parameters of vibration drag-reduction tools are closely related to the drag reduction efficiency. At present, the parameter design of vibration drag reduction is mainly based on field experience but lacks a set of effective theoretical methods. To solve this problem, the strong nonlinear effect of friction force is considered, the dynamic model of drill string with vibration drag-reduction tools is built and the drag reduction laws under different parameters are revealed. On the basis of vibration propagation distance model and inverse torque action distance model, an optimization design method of excitation parameters and installation parameters of vibration drag-reduction tools is established with drag reduction efficiency as the objective function and drill string fatigue failure and hydraulic energy loss as constraint conditions. Finally, the above theoretical model is applied to practice. The results show that the amplitude of the excitation force, the number and installation position of the drag-reduction tools are the main factors affecting drag reduction efficiency. With the increase of excitation force amplitude and the number of drag-reduction tools, the drag reduction efficiency increases continuously., the drag reduction efficiency when the vibration propagation ranges of multiple tools are independent is higher than that when not independent. There is a risk of tubular fatigue failure if the amplitude of the oscillator excitation force is too large, and a risk of too high hydraulic energy loss if too many drag-reduction tools are installed. In the case study, it is recommended to use three vibration drag-reduction tools with excitation force amplitude of 50kN, which are installed at 435m, 1038m and 1641m away from the drill bit respectively, and then a drag reduction efficiency of 54% is achieved.