| 摘要 |
Milling operations are disclosed which require a reduced number of tool trips into a wellbore to create a cut-out pocket or window in a tubular such as casing in the wellbore. Preferably one or two trips are required. A milling system is disclosed which is useful in such operations which includes a whipstock with an orientation member secured thereto and a milling apparatus with one or more mills and an extending joint, if needed, with a central channel therethrough for receiving the orientation member as the milling apparatus moves down in the wellbore. Such a system may be used in a single-trip milling operation. The milling apparatus is useful in a two-trip operation in which no orientation member is attached to the whipstock and in which a starting mill is initially run in on a first trip to create an initial pocket in the casing. In one aspect the mill(s) mill off high center producing a piece of casing which enters into the hollow portion of the mill(s) and, as needed, into a hollow portion of an interconnected extension member such as a pup joint. |
