During the drilling process, stick-slip vibration of the drill string is mainly caused by the nonlinear friction generated by the contact between the drill bit and the rock. To eliminate the fatigue wear of downhole drilling tools caused by stick-slip vibrations, the Fractional-Order Proportional-Integral-Derivative (FOPID) controller is used to suppress stick-slip vibrations in the drill string. Although the FOPID controller can effectively suppress the drill string stick-slip vibration, its structure is flexible and parameter setting is complicated, so it needs to use the corresponding machine learning algorithm for parameter optimization. Based on the principle of torsional vibration, a simplified model of multi-degree-of-freedom drill string is established and its block diagram is designed. The continuous nonlinear friction generated by cutting rock is described by the LuGre friction model. The adaptive learning strategy of genetic algorithm (GA), particle swarm optimization (PSO) and particle swarm optimization improved (IPSO) by arithmetic optimization (AOA) is used to optimize and adjust the controller parameters, and the drill string stick-slip vibration is suppressed to the greatest extent. The results show that: When slight drill string stick-slip vibration occurs, the FOPID controller optimized by machine learning algorithm has a good effect on suppressing drill string stick-slip vibration. However, the FOPID controller cannot get the drill string system which has fallen into serious stick-slip vibration (stuck pipe) out of trouble, and the machine learning algorithm is required to mark a large amount of data on adjacent Wells to train the model. Set a reasonable range of drilling parameters (weight on bit/drive torque) in advance to avoid severe stick-slip vibration (stuck pipe) in the drill string system.
KEYWORDSStick-slip vibration; machine learning; fractional order proportional integral derivative (FOPID) control; optimization algorithm Nomenclature C pb Drill bit viscous damping [(N • m • s)/rad] C rs Viscous damping coefficient of the turn table [(N • m • s)/rad] J zp , J zg , J BH , J zt Rotational inertias of the turn table, drill pipe, BHA, and drill bit, respectively [kg • m 2 ] K Pg , K gB , K Bt Torsional stiffness of the springs between the turn table and drill pipe, drill pipe and BHA, and BHA and drill bit, respectively [(N • m)/rad] N pg , N gB , N Bt Torsional damping of the springs between the turn table and drill pipe, drill pipe and BHA, and BHA and drill bit, respectively [(N • m • s)/rad]