One trip milling system
US5894889A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 21, 1997 |
| Grant date | Apr 20, 1999 |
| Priority date | — |
| Expiry date | Aug 21, 2017 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B29/06
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The side tracking system includes a window mill having a full diameter cutting surface and a reduced diameter tapered cutting surface and a whipstock having a ramp engaging the reduced diameter cutting surface. The materials of the whipstock have a first cutablity and the materials of the casing have a second cutability. The reduced diameter cutting surface contacts the whipstock ramp at a first contact area and the fill diameter cutting surface contacts the wall of the casing at a second contact area. As weight is applied to the mill, there is a first contact stress at the first contact area and a second contact stress at the second contact area. A cutability ratio is the first cutability divided by the second cutability and a contact stress ratio is the first contact stress divided by the second contact stress. The mill cuts the casing rather than the whipstock by maintaining the product of the cutability ratio and the contact stress ratio less than one. Preferably the height of the reduced diameter cutting surface is greater than the height of the full diameter cutting surface. The ramp includes a plurality of surfaces having different angles whereby the rate of deflection of th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.