| Deep and rapid drilling hard formation has been the technical problems for a long time. According to information, Petroleum resources in the western region accounts for over 1/3 of the country where 73% of the oil resources buried in the deep formation. Exploration and development of deep well and hard formation is the most important thing in Oil and gas field development at present. Particle impact drilling is a new drilling technology which rely mainly on particle impacting while mechanical cutting and hydraulic cutting. According to the Particle Drilling Technology Inc's experimental data, particle impact drilling technology has many advantages such as fast drilling rate, small hole deviation and long bit life. Study on particle impact drilling is few for its a new drilling technology.This paper mainly study the process of particle impacting rock by means of software simulation. Describes the role of rock under impact load finite element analysis theory and the corresponding numerical simulation, to analyse the factors of rock breaking effect in particle impact drilling, the process of rock breaking of particle impacting was simulated by establishing three dimensional finite element model with nonlinear finite element software LS-DYNA. To improve effect and efficiency of rock breaking, laws of particle parameters such as the incident velocity, incident angle and particle diameter with volume of rock breaking and rate of energy absorption were studied separately. By analyzing change laws of incident parameters with volume of rock breaking and rate of energy absorption, the incident velocity of 120m/s-150m/s, particle diameter of 2.5mm-4.5mm and incident angle of 0°-10°are advisable. Confining pressure was simplified as rock pre-stressing effect by "implicit-explicit" sequence solution of ANSYS. And, damage evolution process of impacting Rock with confining pressure was analysed. Analysis of rock breaking for particle impacting with/without confining pressure was studied. The influence of different material model on rock breaking effect for particle impacting was discussed. To study the concentration of particles in drilling fluid for the effect of drilling, established the impact of multi-particle continuous finite element model of rock breaking. Analysis results showed that the selection of particle concentration not only to consider the effect of broken rock but also need to consider the interference of particles with each other. According to the simulation results obtained the optimum particle concentration to guide the engineering work. |
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