| 摘要 |
<p>A valve to control flow between outside and inside a tubular member. The valve is housed concentrically in an annular body around a tubular member and may be utilized mounted on an outside mandrel or in a side pocket mandrel which may be included in a well tubing string to control injection or lift gas flow from the well annulus into the tubing. Variable and staged flow restrictors upstream and downstream protect the resilient valve seal from flow cutting and opening closing stresses. The valve is balanced and is not urged to open by increasing outside pressure. The balanced valve minimizes difference between open and close pressures as opening pressure is very near closing pressure. An operating piston, in communication with outside and inside pressures, senses differential pressure and moves the valve axially to open when outside pressure is sufficiently higher than inside pressure. A compressed spring holds the valve closed and opening and closing pressures may be adjusted.</p> |
