| 摘要 |
A system for use in excavating a wellbore that includes a drill string and attached drill bit that has nozzles that are in fluid communication with the drill string. The system receives pressurized slurry of fluid and impactor particles and directs the slurry at a subterranean formation from the nozzles to form the wellbore. Discharge streams are formed from the slurry exiting the nozzles, the discharge streams impact and fracture the formation to remove material. The nozzles are oriented so that the streams excavate in the middle and periphery of the borehole bottom. The nozzles can be oriented to form frusto-conical spray patterns when the bit is rotated, wherein the spray patterns can intersect or overlap.
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