초록 ▼

A drilling assembly for drilling a borehole into an earth formation is disclosed having a drill string extending into the borehole and a jetting device arranged at a lower part of the drill string, the jetting device is provided with a mixing chamber having a first inlet in fluid communication with

A drilling assembly for drilling a borehole into an earth formation is disclosed having a drill string extending into the borehole and a jetting device arranged at a lower part of the drill string, the jetting device is provided with a mixing chamber having a first inlet in fluid communication with a drilling fluid supply conduit, a second inlet for abrasive particles and an outlet which is in fluid communication with a jetting nozzle arranged to jet a stream of abrasive particles and drilling fluid against at least one of the borehole bottom and the borehole wall. The jetting device is further provided with an abrasive particles recirculation system for separating the abrasive particles from the drilling fluid at a selected location where the stream flows from the at least one of the borehole bottom and the borehole wall towards the upper end of the borehole and for supplying the separated abrasive particles to the second inlet.

대표청구항 ▼

A drilling assembly for drilling a borehole into an earth formation is disclosed having a drill string extending into the borehole and a jetting device arranged at a lower part of the drill string, the jetting device is provided with a mixing chamber having a first inlet in fluid communication with

A drilling assembly for drilling a borehole into an earth formation is disclosed having a drill string extending into the borehole and a jetting device arranged at a lower part of the drill string, the jetting device is provided with a mixing chamber having a first inlet in fluid communication with a drilling fluid supply conduit, a second inlet for abrasive particles and an outlet which is in fluid communication with a jetting nozzle arranged to jet a stream of abrasive particles and drilling fluid against at least one of the borehole bottom and the borehole wall. The jetting device is further provided with an abrasive particles recirculation system for separating the abrasive particles from the drilling fluid at a selected location where the stream flows from the at least one of the borehole bottom and the borehole wall towards the upper end of the borehole and for supplying the separated abrasive particles to the second inlet. are comprised of a metal matrix material carrying the diamond grit and at least a portion of the blades is comprised of a softer and more abradable metal matrix material than that of the metal matrix material present in bases of the blades. 17. The rotary drag bit of claim 14, wherein the discrete cutting structures are brazed onto the blades. 18. The rotary drag bit of claim 14, wherein the discrete cutting structures are funaced onto the blades. 19. The rotary drag bit of claim 1, wherein the PDC cutters are oriented with cutting faces substantially facing in a direction of intended bit rotation. 20. The rotary drag bit of claim 19, wherein the PDC cutters include PDC sheaths contiguous with, and extending to the rear of, the cutting faces, taken in the direction of intended bit rotation, extending over substrates of the PDC cutters. 21. The rotary drag bit of claim 1, wherein the blades extend radially outwardly over the bit face in substantially linear fashion. 22. The rotary drag bit of claim 1, wherein the blades extend radially outwardly in spiral fashion. 23. The rotary drag bit of claim 1, wherein the blades extend radially outwardly in a serpentine fashion. 24. A rotary drag bit for drilling subterranean formations, comprising: a bit body having a face extending from a centerline to a gage; a plurality of discrete, mutually separated posts comprising a particulate abrasive material protruding upwardly from the face, wherein the plurality of posts include bases of larger cross-sectional area than outermost ends thereof, wherein the base of at least one of the plurality of posts exhibits a noncircular cross-sectional area. 25. The rotary drag bit of claim 24, wherein the posts are integrally formed with the bit face. 26. The rotary drag bit of claim 25, wherein the bit body comprises a matrix bit body. 27. The rotary drag bit of claim 24, further comprising a plurality of blades on the face extending generally radially outwardly toward the gage, each blade having at least one of the plurality of posts positioned thereon. 28. The rotary drag bit of claim 27, wherein the posts are integrally formed with the blades. 29. The rotary drag bit of claim 28, wherein the blades extend radially outwardly over the bit face in substantially linear fashion. 30. The rotary drag bit of claim 28, wherein the blades extend radially outwardly in spiral fashion. 31. The rotary drag bit of claim 28, wherein the blades extend radially outwardly in a serpentine fashion. 32. The rotary drag bit of claim 24, further comprising a cone portion formed on the face and surrounding the centerline and a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion. 33. The rotary drag bit of claim 32, wherein the plurality of PDC cutters are oriented with cutting faces substantially facing in a direction of intended bit rotation. 34. A method of forming a rotary drill bit for drilling a subterranean formation, comprising: forming a body having a centerline and a face extending from a centerline to a gage; forming a plurality of discrete, mutually separated cutting structures impregnated with a particulate abrasive material and protruding upwardly from the face, each cutting structure having a base with a larger cross sectional area than the outer most ends thereof; and forming the base of at least one of the plurality of discrete, mutually spaced cutting structures to exhibit a noncircular cross-sectional area. 35. The method of claim 34, further comprising configuring a plurality of blades on the face to extend generally radially outwardly toward the gage wherein the plurality of cutting structures are located on the plurality of blades. 36. The method of claim 35, further comprising forming the bit body with a metal matrix material. 37. The method of claim 36, further comprising integrally forming the plurality of discrete, mutually separated cutting structures with the blades. 38. The method o f claim 37, further comprising: forming a cone portion in the face of the body and surrounding the centerline; and disposing a plurality of polycrystalline diamond compact (PDC) cutters on the face within the cone portion. 39. The method of claim 35, further comprising configuring the plurality of blades to provide at least one fluid course therebetween. 40. The method of claim 39, further comprising placing a plurality of ports in the face of the drill bit, each port being in fluid communication with at least one of the plurality of fluid courses. 41. The method of claim 34, further comprising: forming a cone portion in the face of the body and surrounding the centerline; and disposing a plurality of polycrystalline diamond compact (PDC) cutters on the face within the cone portion. 42. The method of claim 34, further comprising forming the bit body as a matrix bit body. 43. The method of claim 42, further comprising forming the cutting structures as posts. 44. The method of claim 43, further comprising integrally forming the posts with the face. 45. The method of claim 34, further comprising configuring each cutting structure to have a substantially planar surface at the outermost end thereof, each substantially planar surface being substantially parallel with the bit face from which the cutting structure protrudes. 46. A method of drilling a subterranean formation with a diamond impregnated matrix body rotary drill bit comprising: providing a plurality of discrete, mutually separated post-like structures on each of a plurality of blades on a face of the rotary drill bit, the plurality of discrete post-like structures containing diamond grit; rotating the rotary drill bit against at least a first subterranean formation under weight on bit and engaging the at least first subterranean formation with the plurality of discrete post-like structures wearing a portion of at least one discrete post-like structures of the plurality as it is engaged with the at least first subterranean formation such that it exposes diamond grit contained in the at least one discrete post-like structure and enlarging a surface area of the at least one discrete post-like structure as it wears against the at least first formation such that an increasing surface area including diamond grit is exposed. 47. The method of claim 46, further comprising wearing the plurality of discrete post-like structures down to the blades and continuing to engage the at least a first formation with diamond grit carried in the blades. 48. A rotary drag bit for drilling subterranean formations, comprising: a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline; a plurality of blades on the face extending generally radially outwardly toward the gage; a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades; and a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein the discrete cutting structures are configured as posts, the posts including bases of larger cross-sectional area than outermost ends thereof and wherein the posts taper from substantially circular outermost ends to substantially oval bases. 49. A rotary drag bit for drilling subterranean formations, comprising: a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline; a plurality of blades on the face extending generally radially outwardly toward the gage; a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades; and a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein at least one of the plurality of discrete cutting structures is formed as a h