| 摘要 |
<p>Apparatus and method of controlling a surface safety valve (300) and a subsurface safety valve (200), comprising providing a self-contained control circuitry including a reservoir (14) for a hydraulic fluid; sensing a drop of pressure in a flowline distal to the surface safety valve (300) and a drop below a pre-established level of pressure in a portion of a hydraulic circuit connected to the subsurface safety valve (200), and responsive to sensing such a drop of pressure: draining fluid to the reservoir (14) from the portion of the circuitry means maintaining the surface safety valve open, then after a first time delay, draining fluid to the reservoir (14) from the circuitry means maintaining the subsurface safety valve open, and then after a second time delay, isolating the subsurface safety valve at least from the portion of the circuitry means proximal to the subsurface safety valve (200).</p> |
