Claims
- 1. A side track cutting apparatus for cutting a secondary borehole through the wall in an existing borehole, comprising:
a cutting tool affixed to the end of a shaft, the cutting tool having a full diameter cutting surface and a reduced diameter cutting surface; and a whipstock having a ramp; said reduced diameter cutting surface contacting said ramp at a first contact area and said full diameter cutting surface contacting the interior of the wall of the borehole at a second contact area; and said first contact area being greater than said second contact area.
- 2. The apparatus of claim 1 wherein a weight is applied to said cutting tool creating a first contact stress between said reduced diameter surface and said ramp at said first contact area and a second contact stress between said full diameter cutting surface and the interior of the wall of the borehole, the ratio of said first contact stress divided by said second contact stress being less than one.
- 3. The apparatus of claim 1 wherein said whipstock has a first cutability and the wall of the borehole has a second cutability and wherein a weight is applied to said cutting tool creating a first contact stress between said tapered cutting surface and said ramp at said first contact area and a second contact stress between said full diameter cutting surface and the interior of the wall of the borehole, a first ratio of said first cutability divided by said second cutability and a second ratio of said first contact stress divided by said second contact stress, said first ratio times said second ratio being less than one.
- 4. The apparatus of claim 1 wherein said reduced diameter surface has a first height and said full cutting surface has a second height, said first height being greater than said second height.
- 5. The apparatus of claim 1 wherein said reduced diameter surface has a first height and said full cutting surface has a second height, said first height being at least 30% of said first and second heights.
- 6. A one trip side track window cutting apparatus for cutting sidetracking windows in a casing having an inside and outside diameter and a second cutability, the casing being positioned in previously drilled boreholes comprising;
a window cutting mill having a full diameter cutting surface and a reduced diameter tapered cutting surface; and a whipstock having a ramp with a taper adjacent to an end and a first cutability, said ramp having a reduced thickness adjacent said end and increasing to an enlarged thickness; said reduced diameter cutting surface contacting said ramp at a first contact area and said full diameter cutting surface contacting the inside diameter of the casing at a second contact area; and said cutting tool creating a first contact stress between said reduced diameter cutting surface and said ramp and a second contact stress between said full diameter cutting surface and the inside diameter of the casing, a first ratio of said first cutability divided by said second cutability and a second ratio of said first contact stress divided by said second contact stress, said first ratio times said second ratio being less than one.
- 7. The apparatus of claim 6 wherein said ramp has an angle in the range of 1 to 45° with respect to the axis of the whipstock.
- 8. The apparatus of claim 6 wherein said ramp has an angle in the range of 2 to 30° with respect to the axis of the whipstock.
- 9. The apparatus of claim 6 wherein said ramp has an angle in the range of 3 to 15° with respect to the axis of the whipstock.
- 10. The apparatus of claim 6 wherein said reduced diameter cutting surface has a first height and said full diameter cutting surface has a second height, said first height being greater than said second height.
- 11. The apparatus of claim 6 wherein said reduced diameter cutting surface has a first height and said full diameter cutting surface has a second height, said first height being at least 30% of said first and second heights.
- 12. The apparatus of claim 6 wherein the tapers of said ramp at said end and said reduced diameter cutting surface are substantially the same.
- 13. The apparatus of claim 6 wherein said mill has a radius and said enlarged thickness of said ramp plus said mill radius are larger than the outside diameter of the casing causing said mill to move laterally through the wall of the casing.
- 14. The apparatus of claim 6 wherein said full diameter cutting surface has a diameter over 75% of the inside diameter of the casing.
- 15. The apparatus as set forth in claim 1 further comprising a second mill, said window mill and said second mill being affixed to a shaft, the second mill being spaced upstream of the window mill, the second mill substantially simultaneously cutting into the casing when the window mill is laterally directed into the casing.
- 16. The invention as set forth in claim 15 wherein the diameter of the second mill is about the same as the diameter of the window mill.
- 17. The invention as set forth in claim 16 further comprising a third mill affixed to a shaft, the third mill being spaced from the second mill and serving to elongate the window cut by the window mill and the second mill, the third mill also serving to dress the window formed in the casing.
- 18. The apparatus as set forth in claim 17 wherein the third mill is a watermelon shaped mill with about the same diameter as the window mill and the second mill.
- 19. The invention as set forth in claim 16 wherein the whipstock forms a ramp surface below said end of the whipstock that is substantially parallel to the axis of the whipstock, the non-angled whipstock ramp surface allowing the window mill and the second upstream mill to simultaneously cut a window, when the second mill window cut merges with the window cut formed by the window mill, the parallel ramp surface transitions into a slightly angled ramp to direct the window mill and the second upstream mill further out through the casing.
- 20. A method of drilling a window in a casing having an inside and outside diameter and disposed in a well comprising:
disposing a first cutting member and a whipstock within the casing; engaging a first contact surface on the first cutting member with a first ramp surface on the whipstock; engaging a second contact surface on the first cutting member with the interior of the casing; applying a force to the first cutting member creating a first contact stress at said first contact area and a second contact stress at said second contact area; providing a first ratio of the cutability of the whipstock to the cutability of the casing and a second ratio of the first contact stress to the second contact stress with the first ratio times the second ratio being less than one; and passing the centerline of the first cutting member from the inside diameter to the outside diameter of the casing.
- 21. A cutter apparatus for cutting a window through the wall in an existing borehole, comprising:
a body having a generally flat bottom cutting surface, a full diameter cutting surface, and a reduced diameter cutting surface disposed between said bottom cutting surface and said full diameter cutting surface; said full diameter cutting surface having a first axial height and being substantially full gauge; said reduced diameter cutting surface having a second axial height; said second axial height being at least 30% of said first plus said second axial heights; and said bottom cutting surface having a diameter which is at least 30% of the diameter of said full diameter cutting surface.
- 22. A method of drilling a window in a casing comprising:
engaging a tapered cutting surface on a mill with a whipstock in the cased borehole; increasing the contact area between the mill and whipstock until the contact stress between the mill and whipstock is less than the contact stress between the mill and casing; and cutting a window in the casing.
- 23. The method of claim 22 further comprising deflecting the center of a bottom cutting surface of the mill from the interior to the exterior of the casing.
- 24. The method of claim 22 wherein the cutability of the whipstock is less than the cutability of the casing.
- 25. A side track cutting apparatus for cutting a secondary borehole in an existing borehole, comprising:
a cutting tool affixed to the end of a shaft, the cutting tool having a tapered cutting surface; and a whipstock having a ramp with an angle substantially the same as the angle of the tapered cutting surface for deflecting the cutting tool into the wall of the existing borehole and drilling the secondary borehole.
- 26. A one trip side track window cutting apparatus for cutting sidetracking windows in a pipe casing positioned in previously drilled boreholes comprising;
a window cutting mill affixed to an end of a shaft, a body of the mill forming a tapered cutting end; and a whipstock forming a ramp, the angle of which substantially parallels an angle of the tapered cutting end of the window mill, said ramp acting as a bearing surface for laterally forcing the window mill into the pipe casing.
- 27. The apparatus of claim 26 wherein the ramp angle is in the range of 1 to 45 degrees with respect to the axis of the whipstock.
- 28. The apparatus of claim 26 wherein the ramp angle is in the range of 2 to 30 degrees with respect to the axis of the whipstock.
- 29. The apparatus of claim 26 wherein the ramp angle is in the range of 3 to 15 degrees with respect to the axis of the whipstock.
- 30. A one trip side track window cutting apparatus for cutting sidetracking windows in a pipe casing positioned in previously drilled boreholes comprising;
a substantially full gage window cutting mill affixed to an end of a shaft, a body of the mill forming a tapered cutting end, and a whipstock forming a ramp adjacent to an end, the angle of which substantially parallels an angle of the tapered cutting end of the window mill, commencement of the window cutting process in the pipe casing results in the angled whipstock ramp laterally forcing the window mill into and through the pipe casing, the parallel ramp acting as a bearing surface during the initial window cutting operation.
- 31. The invention as set forth in claim 25 further comprising a second mill affixed to a shaft, the second mill being spaced upstream of the window mill, the second mill substantially simultaneously cutting into the pipe casing when the window mill is laterally directed into the pipe casing.
- 32. The invention as set forth in claim 31 wherein the second mill is mounted to the same shaft as the window mill.
- 33. The invention as set forth in claim 32 wherein the diameter of the second mill is about the same as the diameter of the window mill.
- 34. The invention as set forth in claim 33 further comprising a third mill affixed to a shaft, the third mill being spaced from the second mill and serving to elongate the window cut by the window mill and the second mill, the third mill also serving to dress the window formed in the pipe casing.
- 35. The invention as set forth in claim 34 wherein the third mill is a watermelon shaped mill with about the same diameter as the window mill and the second mill.
- 36. The invention as set forth in claim 31 wherein the whipstock forms a ramp surface below the angled ramp of the whip stock that is substantially parallel to the axis of the whipstock, the non-angled whipstock ramp surface allowing the window mill and the second upstream mill to simultaneously cut a window, when the second mill window cut merges with the window cut formed by the window mill, the parallel ramp surface transitions into a slightly angled ramp to further direct the window mill and the second upstream mill out through the pipe casing.
- 37. A whipstock for guiding a cutting tool within a casing, comprising:
a body having an axis; a guide surface on said body adapted for guiding engagement with the cutting tool; and said guide surface including a first taper with a first angle to said axis and a second taper with a second angle to said axis.
- 38. The whipstock of claim 37 wherein said guide surface includes a third taper with a third angle to said axis.
- 39. The whipstock of claim 38 wherein said guide surface includes a fourth taper with a fourth angle to said axis.
- 40. The whipstock of claim 39 wherein said guide surface includes a fifth taper with a fifth angle to said axis.
- 41. The whipstock of claim 37 wherein one of said first and second angles is substantially zero degrees to said axis and therefore is substantially parallel with said axis.
- 42. The whipstock of claim 37 wherein said first angle is more than twice said second angle.
- 43. The whipstock of claim 42 wherein said first angle is five times that of said second angle.
- 44. The whipstock of claim 40 wherein said first and fourth angles are substantially equal.
- 45. The whipstock of claim 44 wherein said third and fifth angles are substantially equal.
- 46. The whipstock of claim 37 wherein said guide surface includes surface hardening.
- 47. The whipstock of claim 40 wherein said first and fourth angles are substantially fifteen degrees, said second angle is substantially zero degrees, and said third and fifth angles are substantially three degrees.
- 48. The whipstock of claim 37 wherein said body has a curvature on its outside diameter which substantially conforms to the curvature of the inside diameter of the casing.
- 49. An apparatus for cutting a window in a casing disposed within a well, comprising:
a cutting assembly having a cutting assembly axis and including a first cutting member with a first bearing surface forming a first bearing angle with said cutting assembly axis; a guide member having a guide member axis and including a guide surface with a first tapered wedge surface having a first angle with said guide member axis and a second surface having a second angle with said guide member axis; said first bearing surface engaging said first tapered wedge surface for deflecting said cutting member and then said first bearing surface engaging said second surface for guiding said cutting assembly.
- 50. The apparatus of claim 49 wherein said cutting member has a second bearing surface forming a second bearing angle with said cutting assembly axis.
- 51. The apparatus of claim 50 wherein said second bearing angle has substantially the same angle as said second angle.
- 52. The apparatus of claim 49 wherein said cutting member includes a bearing surface for cutting full gage.
- 53. The apparatus of claim 49 wherein said first bearing angle is in the range of 0 to 45 degrees with respect to the axis of the cutting assembly.
- 54. The apparatus of claim 50 wherein said second bearing angle is in the range of 0 to 45 degrees with respect to the axis of the cutting assembly.
- 55. The apparatus of claim 52 wherein said bearing surface is parallel to the axis of the cutting assembly.
- 56. The apparatus of claim 50 wherein said cutting assembly further includes a second cutting member disposed a predetermined distance from said first cutting member.
- 57. The apparatus of claim 56 wherein said guide surface includes a non-tapered surface adjacent said first tapered wedge surface, said non-tapered surface having a length substantially equal to or greater than said distance between said first and second cutting members.
- 58. The apparatus of claim 56 wherein said second cutting member cuts full gage.
- 59. The apparatus of claim 56 wherein said cutting assembly includes a third cutting member disposed a predetermined length from said second cutting member.
- 60. A method of drilling a window in a casing disposed in a well comprising the steps of:
releasably connecting a starter cutting member to one end of a whipstock; engaging a bearing surface on the starter cutting member with an initial wedge surface on the whipstock; disposing the starter cutting member and whipstock within the casing; disconnecting the starter cutting member from the whipstock; deflecting the starter cutting member into engagement with the casing; engaging a second bearing surface on the starter cutting member with a subsequent wedge surface on the whipstock; and passing the centerline of the starter cutting member from the inside diameter to the outside diameter of the casing.
- 61. The method of claim 60 wherein the deflecting step includes paralleling the bearing surface of the starter cutting member with the initial wedge surface on the whipstock.
- 62. A method of drilling a window in a casing disposed in a well comprising the steps of:
lowering a milling assembly releasably connected to a whipstock assembly into the casing; anchoring the whipstock assembly within the casing; disconnecting the milling assembly from the whipstock assembly; lowering and rotating the milling assembly having at least two full gage cutting members; engaging a bearing surface on one of the cutting members with an initial wedge surface on the face of the whipstock of the whipstock assembly; deflecting the one cutting member into engagement with the casing; passing the one cutting member along a non-tapered surface of the whipstock until the second cutting member is adjacent the initial wedge surface; guiding the one cutting member along a subsequent wedge surface on the face of the whipstock until the center of the one cutting member is adjacent the inside diameter of the casing; engaging the one cutting member with a steep wedge surface; deflecting the one cutting member against the casing until the center of the one cutting member passes to the outside diameter of the casing; and guiding the one cutting member along another subsequent wedge surface on the face of the whipstock until the window is cut.
- 63. A mill for cutting a secondary borehole in an existing borehole comprising:
a body; a plurality of cutting surfaces having a angle with the axis of the body; one of said cutting surfaces including a bore for receiving a hollow shear member whereby upon shearing said shear member, said bore acts as a nozzle.
- 64. The mill of claim 63 wherein another one of the cutting surfaces includes a bore for attachment to a coupling whereby upon milling off said coupling, said coupling bore acts as another nozzle.
- 65. The mill of claim 64 wherein said coupling includes a reduced portion therearound causing said coupling to mill cleanly from said mill.
- 66. A whipstock for deflecting a cutting tool into the wall of a casing, comprising:
a body; and a guide surface on said body adapted for engagement with the cutting tool, said guide surface varying the degree of deflection of the cutting tool as the cutting tool is lowered through the casing against said guide surface.
- 67. The whipstock of claim 66 wherein said guide surface includes varying tapers.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09/021,630 filed Feb. 10, 1998, hereby incorporated herein by reference, which is a continuation-in-part of U.S. patent application Ser. No. 08/642,829 filed May 3, 1996, now U.S. Pat. No. 5,771,972, hereby incorporated herein by reference, and is related to U.S. patent application entitled Two Trip Window Cutting System, Ser. No. 572,592, filed Dec. 14, 1995, hereby incorporated herein by reference, and U.S. patent application Ser. No. 08/916,932 filed Aug. 21, 1997, now U.S. Pat. No. 5,894,889, hereby incorporated herein by reference.
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
09021630 |
Feb 1998 |
US |
Child |
09303049 |
Apr 1999 |
US |
Parent |
08642829 |
May 1996 |
US |
Child |
09021630 |
Feb 1998 |
US |