Research On Auto-drilling System Based On Disc Brakes And Double Hydraulic Cylinders Of Ultra-deep Drilling Rig

The auto drilling is that drilling tools are sent automatically not relying on drillers inthe course of drilling. The auto drilling can keep the given bit pressure constant throughbeing adjusted by the control system at the request of drilling technology. The autodrilling does not only send drillers free, but also reduce the workers labor intensity. It canmake the drill bit feed evenly and the bit pressure less volatile, improve the well drillingquality effectively and reduce the well drilling cost. The auto drilling can make thedrilling become more safe and reliable.In this paper, the structure and the control method of the auto drilling system wasstudied on account of ultra-deep drilling rigs’ big hook load, complex factors and bitpressure controlled hardly for making the ultra-deep drilling rigs’ bit pressure meetrequirement of control accuracy. This paper mainly includes several aspects as followed:First of all, the drilling method of the combination of the disc brake and hydrauliccylinder was put forward on the basis of analyzing the principle and structurecharacteristics of the auto drilling particularly in view of the auto drilling research athome and abroad. The control method used electro-hydraulic proportional control basedon fuzzy PID algorithm. The hydraulic system used the drilling way of the combinationof the disc brake and double hydraulic cylinders. Parameters of the winch disc brakesystem and the bit pressure given system were calculated based on the known systemparameters. The electrohydraulic proportional overflow valve was used to control thedisc brake system and the bit pressure given system.Secondly, the working principle of the guiding electro-hydraulic proportionaloverflow valve and the overflow valve-controlled cylinder was analyzed in the system.Factors of influencing their dynamic performance was analyzed by establishing amathematical model. The load of the disc brake system and the bit pressure given systemwas analyzed and simplified reasonably. Disc braking torque to the winch barrel, the bitpressure, the velocity and the acceleration that drill stems relative to the hook and the top drive were analyzed by using D’ Alembert Principle, virtual work principle and thegeneral equations of dynamics. The work was prepared for the next step of simulationanalysis and experiments.Thirdly, simulation models of disc brake system and bit pressure given system werebuilt by using AMESim. The working process of safety gear and jaw was simulated toprove the correctness of the system in theory. Drilling bit pressure of the auto drillingsystem was simulated. The fuzzy PID controller was designed in Simulink. Drilling bitpressure of the auto drilling system controlled by the fuzzy PID controller was simulatedand analyzed by using Co-Simulation interface of AMESim and MATLAB. Parametersof the fuzzy controller were determined. The result of bit pressure simulation showed thatthe control precision of the auto drilling system can meet the design requirements.Finally, experiments of the drilling depth, bit pressure and jaw working pressure ofthe auto drilling system were done according to the progress of the project. Therationality of the simulation model and the reliability of the designed system wereverified by comparing and analyzing experimental data and simulation results.