Analysis And Research On The Motion Pattern Of The Lower Drill String In Torsional Swing Motion

In recent years,oil and gas exploration and development technology has continuously developed into unconventional fields,and horizontal wells and extended reach wells have become important technical support for improving the production of oil and gas reservoirs.However,in the process of sliding drilling,the problem of supporting pressure on the drill string has become the main bottleneck restricting drilling speed and efficiency.To solve this problem,foreign companies such as Schlumberger and Baker Hughes have developed a torsion pendulum drag reduction system for surface drill strings,and have achieved success in field applications.Although some progress has been made in drag reduction technology in China,there are still problems such as a lack of theoretical knowledge and uneven effects of torsion pendulum systems.It is necessary to further optimize the torque swing drag reduction technology to maximize the drilling speed and efficiency.The main research work of this article is as follows:(1)In the theoretical analysis,the model is established using the longitudinal and transverse curved beam model and the soft rod model.Taking the borehole trajectory of DXX5064 as an example,the friction torque model established is used for calculation.(2)The adverse motion patterns of the drill string are classified into stick-slip vibration and buckling deformation for analysis.The results show that the stick-slip vibration effect can be reduced by controlling the magnitude of linear torque load and frictional load.The deformation of the sinusoidal buckling of the string is not related to the torque applied.Spiral buckling is related to the torque applied to the string.Based on the similarity principle,a test platform was built to observe the movement of the drill string.It was found that the buckling state of the simulated drill string in the horizontal wellbore was: initial state-two-dimensional lateral buckling-three-dimensional lateral buckling-spiral buckling;The contact behavior of the drill string successively experiences a non-contact state,a point contact state,and a continuous contact state.(3)In order to suppress the adverse motion patterns of drill string,such as stick-slip vibration and buckling deformation,an adaptive control algorithm for drill string torque based on intelligent PID neural network is proposed.The experimental platform for torsional pendulum motion control was built and the experimental results showed that the PID neural network algorithm improved the control accuracy of the system,with fast response speed and good robustness.The intelligent PIDNN control system established can better control the speed of the rotary table,with a speed fluctuation range of within 0.8%;Compared to PSO algorithm and GA algorithm,using SOA algorithm to optimize PIDNN has achieved better results,making up for the difficulty in determining the weight of PIDNN controllers,and enabling online adjustment of PIDNN controllers.