Patent ID: 7661480

Claim:
A method for rupturing a glass disc during the completion of a well, the glass disc being positioned in a section of downhole production tubing in the well, the tubing being positioned in a casing extending from the wellhead to a position below the production tubing section containing the glass disc, the wellhead being fitted with a Christmas tree for controlling hydrocarbon production, and a wellhead isolation tool attached to the wellhead downstream of the Christmas tree, the method comprising the steps of: a. adjusting the wellhead isolation tool to isolate the Christmas tree from downhole hydraulic pressure forces; b. introducing a pressurized rupturing fluid into a section of the production tubing below the wellhead isolation tool that is in communication with the glass disc; c. introducing a substantially incompressible fluid into the annular space between the production tubing and the surrounding casing; and d. increasing the hydrostatic pressure on the rupturing fluid in the production tubing to a level that is sufficient to rupture the disc while simultaneously maintaining the pressure of the fluid in the annular space at a predetermined value in order to prevent the tubing from rupturing and/or collapsing as a result of the pressure differential.