Effects of jet parameters on crack propagation by double-hole liquid CO2 phase change impact rock
The shape and impact direction of the jet during the phase change of liquid CO2 affect the rock breaking effect.Based on the self-developed experimental system and LS-DYNA numerical simulation,the rock crack growth rule of dual hole liquid CO2 under different air flow release direction combinations was studied.The results show that the rock cracks cannot propagate between the two holes when the two holes are oppositely impacted in the X direction.When the two holes are impacted in the X direction,a through crack is formed between the two holes.When the two holes are impacted in the same direction in Y direction,the cracks continue to expand along the initial impact direction and form multiple cracks around the holes.The numerical simulation results show that under the impact of different combination of release ports,the crack forms a penetration between the two holes when the X direction is relatively impacted,The initial crack continues to expand throughout the front and rear sides.The crack of the sample under the back impact in the X direction mainly expands around the reserved hole.Under the co-directional impact in the Y direction,the internal cracks of the sample expand in the opposite direction of the initial airflow impact direction,and no penetrating cracks are formed.In terms of the effect of crack directional expansion,the relative impact effect of the X direction of the double hole is the best,the co-directional impact in Y direction is the second,the reverse impact in the X direction is the worst.In terms of the number of main crack growth on the top surface,the reverse impact in the X direction is the worst,the impact in Y direction is the second,and the relative impact effect in X direction is the least.The research results can provide guidance for the application of CO2 impact fracturing technology.
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