| Crushing mechanism of the deep complex formation and efficient rock breakingmethod is an important direction of research in deep well drilling technology. And theuse of hydraulic energy to increase penetration rate is a feasible way. Bottom hole directmodulated pulsed particle jet is a novel technique. It combines abrasive jet and theadvantage of water jet, that is, using cuttings generated by drilling bottom hole directlyas medium, forming modulated pulse particle jet to impact on the bottom hole. Throughthe synergistic effect of the use of cuttings impacting and grinding, and factors such ashydraulic pulsation, the tool can improve drilling efficiency.Analyzed the comprehensive utilization of pulse jet and particle impact jet energyto improve the efficiency of rock breaking. Establisded two-phase flow field, andreveals fluid field of particle jets. Particle diameter, particle density, confining pressureand the inlet pressure of the actual working conditions of the bottomhole pulse particlejet modulation found under downhole conditions, self-priming annulus fluidself-oscillation cavity stable topical negative pressure is generated, which can be formedinside and outside in the modulation tool pressure, introducing the particles of theannulus, involved in the modulation generates pulses particle jet. The study confirmedthat the jet modulation principles of the tool is feasible.Through numerical simulation, the characteristics of the flow field in the internalstructure of the modulation tool parameter are reasonable. According to the internalflow characteristics, based on LES large eddy simulation model, analyze the modulationtool chamber pressure and velocity field, from jet pulsation structure matching thecharacteristics of the flow field in the exploration tools. Large eddy simulation oftransient changes in bottom hole direct modulated pulse particle jet pulsationcharacteristics, the annulus fluid reveals inhalation strengthen the mechanism ofself-excited oscillation pulsed jet performance, and we found that the structure of theself-oscillation cavity parameters’ effect on jet. The pulsating effect of self-excitedoscillation jet performance was significantly better than the non-inhalation pulse jet.Developed based on the results of the numerical simulation and the abovetheoretical analysis, improved the current lab apparatus, established rock-breakingexperimental test-bed, and started study of jet rock breaking tests. The results show thatthe modulation tool exit velocity pulsation become larger, the better the effect of rockbreaking will be. They showed a significant linear correlation. The export value of the velocity fluctuation is preferred based on orthogonal experimental method for thenumerical simulation test, determined the structure parameters of the bottom holedirectly modulated pulsed particle jet tool.Then combine the rock breaking experiment and numerical simulation, and the rockbreaking effect and the flow field of different structural modulation tools, analyze theimpact the bottom hole directly modulated pulse particle jet tool rock breaking effect,and analysis tools for the relationship between the characteristic parameters andstandard parameters of flow field, finally find characteristics of the tools used toevaluate the effect of rock breaking. First determine the structural parameters of themodulation tools, further expanding the parameters of orthogonal experimental methodto determine the structure of the bottom of the well directly modulated pulse particle jettools, then participate in defining the modulation tool structure optimization by meansof numerical simulation of the entire hydraulic structures, so to determine the beststructure of the bottom hole directly modulated pulse particle jet tool.According to the field requirement of the real drilling condition, we developedfull-scale first generation tool and, in order to verify theoretical studies, we have a fieldtest. Based on the problems revealed in the field, after following testing andmaintenance work, the second generation of the tool has been developed. The well testresults prove that the developed directly modulated pulse particle jet tool structure isreasonable, safe and reliable, and it can improve ROP. It provided a theoretical base,promoted the development of the theory and technology of bottom hole directlymodulated pulse particle jet tool drilling technology. |
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