Claims
- 1. A side track cutting apparatus mounted on a pipe string for cutting a secondary borehole in an existing borehole, comprising:
- a shaft having a rigid portion and a flexible portion;
- a first cutting tool disposed on an end of said flexible portion;
- a second cutting tool disposed on said rigid portion;
- said flexible portion being continuous from said rigid portion to said first cutting tool; and
- said flexible portion flexing as said first cutting tool engages the existing borehole.
- 2. The apparatus of claim 1 wherein said rigid portion has a first diameter and said flexible portion has a second diameter smaller than said first diameter.
- 3. The apparatus of claim 1 wherein a transition portion is formed between said rigid portion and said flexible portion.
- 4. The apparatus of claim 1 wherein said first cutting tool is under gauge and said second cutting tool is substantially full gauge.
- 5. The apparatus of claim 1 further including a third cutting tool disposed on said flexible portion of said shaft between said first and second cutting tools.
- 6. The apparatus of claim 5 wherein said third cutting tool has a cutting gauge sized between that of said first and second cutting tools.
- 7. The apparatus of claim 1 wherein said flexible portion and said rigid portion are integral.
- 8. A side track cutting apparatus for cutting a secondary borehole in an existing borehole, comprising:
- a milling assembly including a shaft with a stiff portion and a flexible portion, a first cutting tool mounted on an end of said flexible portion and a second cutting tool mounted on said stiff portion;
- a whipstock having a ramp portion;
- said first cutting tool releasably attached to one end of said whipstock;
- said flexible portion flexing as said ramp portion places a side load on said first cutting tool; and
- said flexible portion having a length greater than twice its diameter.
- 9. The apparatus of claim 7 further including a bearing pad disposed between said first cutting tool and said ramp portion where said first cutting tool is attached to said whipstock.
- 10. The apparatus of claim 8 wherein said second cutting tool is substantially full gauge and therefore in engagement with said borehole causing said shaft to flex between said first and second cutting tools as said ramp portion forces said first cutting tool into the borehole.
- 11. A method of cutting a secondary borehole in a cased borehole comprising the steps of:
- disposing a full gauge cutting tool on a shaft with an under gauge cutting tool on the end of the shaft;
- placing a side load on the under gauge cutting tool; and
- flexing that portion of the shaft extending between the full gauge cutting tool and under gauge cutting tool.
CROSS REFERENCE TO RELATED APPLICATIONS
This application 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 and Ser. No. 08/642,824 filed May 3, 1996, now U.S. Pat. No. 5,816,324, both hereby incorporated herein by reference and relates to a patent application entitled Two Trip Window Cutting system, Ser. No. 572,592, filed Feb. 14, 1995, now U.S. Pat. No. 5,657,820, hereby incorporated herein by reference.
US Referenced Citations (10)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2303158 |
Dec 1997 |
GBX |
Non-Patent Literature Citations (2)
Entry |
A-Z Grant International; Casing Sidetrack Systems; undated; (7 pgs.). |
Track Master Sidetracking System; Feb. 24, 1995; (1 sheet). |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
642829 |
May 1996 |
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