| With the deepening of oil and gas exploration,the well depth extends from the middle to the shallow layer to the deep and ultra-deep layers,and the drilling difficulty is gradually increased.Therefore,the drilling speed increase is the focus of related research,and the speed of the drilling speed has a great relationship with the rock breaking efficiency.The bit resonance rock breaking technology is an important branch of the future drilling speed.The rock at the bottom of the working face can accelerate the fracture under the resonance of the drill bit.However,the research on the fracture mechanism of the rock under the current simple harmonic vibration is in its infancy.The fracture effect of the simple harmonic vibration on the rock and its rock breaking mechanism are still unclear..Therefore,in view of this problem,this paper studies the mechanism of rock fracture under the iMPact of bit vibration.In this paper,the discrete element method is used as the theoretical basis.The rock mechanics parameters of the rock medium and the rock resonance frequency are measured respectively.The rock breaking effect of the rock under different harmonic vibrations is analyzed.Through the discrete element simulation and laboratory experiments,the mechanical behavior of rock under simple harmonic vibration conditions is analyzed,and the mechanism of rock fracture under simple harmonic vibration is revealed.Mastering the mechanism of rock fragmentation under resonant conditions has important guiding significance for improving the drilling rate and field application.The research contents are as follows:(1)Using the ultrasonic test system and the triaxial rock mechanics test system to measure the rock resonance frequency and the physical and mechanical parameters of the rock.By analyzing the influence of rock composition,density,volume and other factors on the rock resonance frequency,it is known that the rock contains The different components will have different effects on their resonance frequency,and the negative correlation between the mass of the rock and its resonance frequency is positively correlated with the depth of the formation,but the resonance frequency of the rock ultimately depends on the magnitude of the excitation frequency.When the excitation frequency range is determined,the rock The resonant frequency is also determined.(2)According to the mechanical properties of rock combined with discrete element theory,the three-dimensional compressive and tensile strength models of rock are established.Through hundreds of simulations and 26 sets of laboratory tests,the link key parameters between the particles are calibrated to the model.The influencing factors were analyzed and the dynamic crushing process was given.By fitting the indoor experimental results and the simulation results,it is known that the stress-strain curve of rock failure has a basic uniform error of about 3.5%,which verifies the accuracy of the model.(3)The PDC single-tooth cutting discrete element model is established.The forward tilt angle of the PDC cutting teeth is optimized by introducing the crushing specific work.By adding the simple harmonic vibrations of different frequencies to the PDC teeth,the coMParison is carried out under the presence or absence of vibration.The rock-breaking effect,combined with the indoor rock-breaking test,shows that the speed of the mechanical drill is less than 50% when the simple harmonic vibration is not applied... |
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