| 摘要 |
A downhole, inline well safety shutoff valve has a spring-loaded, normally closed flapper shutoff valve element that may be opened by a downwardly driven movement of an operator tube coaxially and slidably disposed within the tubing string bore. The operator tube is vertically driven by a rod structure disposed in an offset passageway in the safety valve housing and operated by fluid control pressure transmitted thereto from the surface. To substantially preclude undesirable communication in the passageway between pressurized production fluid and pressurized rod control fluid, the rod structure is slidably carried within a specially designed seal structure including a cylindrical sleeve coaxially received in the offset passageway, and a sealing ring captively retained between the top end of the sleeve and an annular ledge formed in the passageway. The sealing ring functions to create a dynamic seal around the rod side surface and a static seal between the ring and the interior passageway surface. When the rod structure is driven upwardly relative to the sleeve, a seating ball carried by the top end of the rod structure contacts an annular sealing surface within the offset passageway and forms therewith a first static seal above the sealing ring. When the rod structure is driven downwardly relative to the sleeve, an undercut portion of the rod structure forms a second static seal with a lower end portion of the sleeve.
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