Dynamic Model and Quantitative Analysis of Stick-Slip Vibration in Horizontal Well

Abstract

Stick-slip is very harmful to the service life of drillstring. The extended Hamilton principle is applied in the paper. Then, finite element method (FEM) is employed to describe the model. The drillstring-borehole impact and friction, fluid-structure interaction, bit-rock interaction, and gravity are considered in this model. The influence of axial and torsional excitation on stick-slip is analyzed. The nonlinear motion predicted by the model is consistent with the observation results in the experiments. The research shows that the fluctuation amplitude of the bit angular velocity also increases along with the increase of driving angular velocity (torsional excitation). However, both the ratio of the maximum angular velocity of the stick-slip vibration and the fluctuation of the angular velocity are continuously reduced. Meanwhile, the strength of the stick-slip vibration has a tendency to slow down. As the axial load (axial excitation) increases, the fluctuation of the maximum angular speed of the stick-slip vibration does not change significantly, but the smaller load causes a smaller stick duration.

Fuzzy Smith predictor–based active disturbance rejection controller for time-delay systems with application to drilling stick–slip vibration control

“…2 For suppressing drilling stick-slip vibrations, some scholars have tried to suppress the stick-slip vibrations from the perspective of improving drilling equipment and drilling methods and from the perspective of the bit breaking method 3 and vibration energy suppression. 4 Another group of scholars started from the analysis of the kinetic mechanism of drilling stick-slip vibrations, 5,6 established a mathematical model of the oil drilling system (ODS) to reproduce and restore stick-slip vibrations, [7][8][9] and then designed a stick-slip vibration controller for the ODS 10,11 for suppressing stick-slip vibrations. In fact, the main problem with the design of the drilling stick-slip vibration suppression controller is the uncertainty of the complex environment in which the drilling system is located, the impossibility of accurate modelling, and the delay in the physical process of output torque transfer.…”