The Analysis Of Coal Fracture Classification And Rock Breaking Efficiency Numerical Simulation

In actual engineering, in order to maintain the high drilling speed with different depth ofcoal, we often improved the drilling pressure and rotation speed, and makes the boreholecollapse accidents happen, not only reduce the drilling efficiency, but also increase theeconomic loss and the engineering time. How to conduct the high efficient drilling withmaintaining the safety case is the research priorities of this paper.In the paper，using the relevant GSI theoretical formulas acquired from1000m depth ofQinshui basin well-logging information and Hoek-Brown criterion to determine the valuerange of coal strength under different broken classification prediction.Through the research of PDC bit breaking rock, established the impact crusher of coalabout single tooth, with the maximum kinetic energy of the drill had been retrieved. Thissolved the problems of the long computation time and insufficient memory. With the processof single tooth impact the coal, analysis the stress distribution of coal and the influence to thebit with the coal. At the same time, make the influence of rock breaking summary about theparameters of single tooth design and the physical parameters change of coal.Through the coal breaking simulation analysis with PDC and percussion bit underdifferent fracture classification of coal, observed the coal breaking effect, stress distribution,and the displacement change state, make the summary about well bore stability with twokinds of bit under static loads. Then, by changing the type of load, applied engineering squarewave, triangle wave and sine wave load, observe the rock breaking efficiency, the influence ofthe well bore stability under different load types, and optimized construction drill and loadingwaveform.Finally, through the simulation analysis, summarized the threshold bit weight andpredicting drilling speed under different classification of the coal, improved the rock breakingefficiency and reduced the risk in the working process, provide certain reference significance.