PRELIMINARY MILLED WINDOWS HAVING SHELL FROM COMPOSITE MATERIAL Russian patent published in 2017 - IPC E21B29/08 E21B7/08 

FIELD: oil and gas industry.

SUBSTANCE: boring casing section includes a housing comprising a wall, a window that represents an opening in the wall of housing, and a shell that: (A) consists of a composite material; (B) is located on the outer surface of housing; (C) covers the window; and (D) enters at least a sufficient distance beyond the window perimeter so that bore casing section has the desired nominal pressure at the location of the window. Composite material comprises a first layer constituting a pressure sensing layer adapted to withstand a particular pressure difference, and a second layer which is a structural layer providing the desired strength of composite material. When a lateral wellbore is created in the subsurface formation, a bore casing is introduced into the wellbore, that contains at least one section of bore casing, at least a part of shell is drilled from within the bore casing to open the said window; and lateral wellbore, adjacent to the opened window, is form.

EFFECT: increasing the reliability and strength of shell for the preliminary milled window.

20 cl, 5 dwg