| 摘要 |
<p>IMPROVED VENT ASSEMBLY A vent assembly for use in a tubing string located downhole in a borehole. The vent assembly is moved to the open position by a fishing tool attached to a slick line and run downhole through the tubing string into engagement therewith. The vent assembly includes an elongated, annular piston which slidably and sealingly engages the inside peripheral wall of a housing. The housing has radial ports which are covered by spaced seals located on the annular piston. One of the seals is larger in diameter than the other, thereby presenting different surface areas to the bottomhole fluids of the borehole within which the assembly is located. A sliding valve element underlies the annular piston and covers a relatively small bleed port so that when the valve element is moved by the wireline actuated tool to uncover the bleed port, the pressure differential across the housing is equalized. The sliding valve element is engaged by the wireline fishing tool and oved uphole to uncover the bleed port and thereafter, moved further uphole to open the vent port.</p> |
