Study On Stick-Slip Vibration Adaptive Control System For Drill String

Drill-string viscous-slip vibration is a kind of “motion-rest-remove-reset” vibration mode,which often occurs in drilling conditions where the depth of drilling reaches several kilometers.Once the stick-slip vibration occurs,it will easily lead to a significant decrease in drilling efficiency,damage to the drill bit,and failure of the drill stem.The main purpose of this paper is to study the stick-slip vibration self-adaptive control system of the drill string.The main purpose is to suppress the stick-slip vibration of the drill string,reduce the drilling accident,and improve the drilling efficiency.In this paper,the stick-slip vibration adaptive control system for drill string is mainly studied from the following aspects:(1)The top turntable and bottom hole assembly are each equivalent to two lumped masses.The mass of the drill string is equivalent to the drill tool assembly.The drill string is equivalent to a spring without torsion stiffness with inertia,and a dynamic spring-mass model of the drill string is established.The force-analysis of the spring-mass model of the drill string system was performed,the movement model of the drill string system was established,and the mechanism of the stick-slip vibration of the drill string was analyzed.(2)A Luenberger observer was established to estimate the actual movement of the drill assembly.Based on the observer data,the drill-cylinder visco-slip vibration model reference adaptive control algorithm is designed by using the local parameter optimization design method,and the stability analysis of the algorithm is performed.The control system simulation model was set up to provide theoretical support for the implementation of the stick-slip vibration adaptive control system.(3)The implementation of the adaptive control system for the viscous-slip vibration of the drill string is completed,including three aspects:1)software and hardware design of the human-computer interaction unit,2)soft and hard design of the control algorithm unit,3)hardware and software design of the interface conversion unit.In order to provide users with a friendly interface,the human-computer interaction unit adopts the embedded development and design mode of Linux+ARM.The adaptive control algorithm unit uses the TMS320F2812 DSP chip as the main control chip to design the system to meet the real-time requirements of the system.The external interface unit adopts STM32F407 as the control chip for system design to meet the needs of system interaction with external information.(4)Based on the completion of the adaptive control system for the stick-slip vibration of the drill string,a semi-physical simulation experiment was conducted.The experiment adopts a model-based design mode.The experimental results show that the adaptive control system for the stick-slip vibration of the drill string can quickly converge the motor's speed and torque amplitude,and the stick-slip vibration disappears.It proves the completeness of the control system and provides basic support for the well test.(5)The drill string stick-slip vibration control system was connected to the top drive inverter to carry out the well test under actual conditions.The experimental results show that the designed stick-slip vibration adaptive control system can effectively suppress the stick-slip vibration of the drill string.This also reflects the validity and stability of Luenberger's observer,model reference adaptive control law,and stick-slip vibration adaptive control system designed in this paper,as well as the correctness of the simulation experiment and the feasibility of the control system.