| In United States, some drilling engineers were inspired by the particles impact rock, and proposed particle impact drilling technology(PID for short).using high-speed spherical particles to simulate projectiles to break hard rock.The technology made use of drilling fluid to carry rigid spherical particles through a specially designed drill bit, particles break rock in 150m/s speed with high frequency, attached by cogging-breaking rock, It will resolve the problem of lower drilling speed and longer cycle in the process of drilling hard formation and improve the efficiency of the hard formation rock breaking.At present, the United States Particle Drilling Technology Inc. has conducted essential research and field application tests, proved that the effect of rock breaking is particularly obviously in hard formation, The drilling speed is 2 to 4 times than conventional drilling.According to on-site application, mechanism of rock breaking and bit design are need to be studied and improved. In this paper, numerical simulation and laboratory testing are combined to study the rules of rock breaking, in order to optimize the structural design of the new PID bit,. This paper mainly complete the following aspects of work.(1) Use the finite element analysis software named ANSYS/LS-DYNA to simulate the process of the particles impact rock and explore the rules of particles impact drilling;(2) Selecte the appropriate parameters of particles for indoor rock breaking test, obtain the best parameters (injection volume of particles, the impact velocity , incident angle, etc.);(3) Analyze the rock breaking mechanism, optimize nozzle structure and design the bit.
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