| 摘要 |
A valve seat, adapted for receiving a plug having a plugging dimension, for use in a fluid conduit of a downhole tool having an inner wall disposed about a central longitudinal axis, said inner wall defining a central bore for passage of fluid from an upstream location to a downstream location, comprising: a substantially cylindrical body having a first bore therethrough defined by an inner surface of the body and the body being of a first volume; a first clearance through said body, defined by a portion of said inner surface, which is smaller than the plugging dimension; a seating surface located upon the inner surface facing upstream for sealingly engaging with said plug and substantially occluding passage of said fluid from said upstream location to said downstream location; wherein a pressure differential is developed across said valve seat when said plug sealingly engages said seating surface, applying force to said seating surface; said body being formed of an elastic material which compresses to a second volume, smaller than said first volume, by application of said force to provide a second clearance to said body which is greater than the plugging dimension, and thus allows passage to said plug downstream within said fluid conduit; and wherein after passage of said plug, said body returns to said first volume with substantially said first clearance. |
