Patent ID: 7503407

Claim:
A method of excavating a subterranean formation using a circulation fluid, the method comprising: pumping the circulation fluid through at least one nozzle positioned adjacent a distal end of a pipe string and adjacent a subterranean formation such that a velocity of the fluid when exiting said at least one nozzle is substantially greater than a velocity of the fluid entering said at least one nozzle in the lower end of the pipe string; introducing a plurality of solid material impactors through an impactor injection port into the fluid downstream of a fluid circulation pump to circulate said plurality of solid material impactors with said fluid through said nozzle, a substantial portion by weight of said solid material impactors having a mean diameter of equal to or less than approximately 0.075 inches, a substantial portion of said plurality of solid material impactors also being substantially spherical, having a substantially uniform outer diameter, and substantially rigid; pumping the fluid at a pressure level and a flow rate level sufficient to satisfy an impactor mass-velocity relationship such that a substantial portion by weight of said plurality of solid material impactors has a minimum average kinetic energy of approximately 0.075 Ft Lbs when exiting said at least one nozzle; and compressing the formation by contacting the formation in a selected zone with said substantial portion by weight of said plurality of solid material impactors to fracture and structurally alter the formation thereby excavating the subterranean formation.