| 摘要 |
The present invention discloses and claims methods and apparatus for forming an opening or a window in a downhole tubular for the subsequent formation of a lateral wellbore. In one aspect of the invention, a thermite containing apparatus is run into the wellbore on a wire line and a widow is subsequently formed in casing wall. In another aspect of the invention, the apparatus includes a run-in string or drill stem with a drill bit attached to a lower end thereof. A diverter, like a whipstock is attached temporarily to the drill bit with a mechanically shearable connection. At a lower end of the whipstock, a container is formed and connected thereto. The container is designed to house a predetermined amount of exothermic material at one side thereof adjacent the portion of casing where the window or opening will be formed. A telescopic joint extends between the bottom of the container and an anchor therebelow and the telescopic joint is in an extended position when the apparatus is run into a wellbore. In use, the exothermic material, like thermite is ignited and the window is formed in the casing. The telescopic joint is then caused to move to a second position, locating the whipstock adjacent the newly formed casing window. |
