| 摘要 |
<p>Well control valve to be installed in a tubing string for use in killing a well through use of fluid under pressure pumped down through the annulus surrounding the tubing string. When the annulus pressure exceeds a predetermined value, the valve is opened to permit the kill fluid to flow into and through the tubing string into the producing formation. The valve contains spaced upper and lower closure members or rupturable discs defining an atmospheric chamber therebetween. The upstream side of the upper disc is subject to the normal hydrostatic pressure of the fluid in the annulus, and also to an increase in the pressure of the annulus fluid above normal hydrostatic pressure, but its downstream side is subjected initially to the atmospheric pressure in the chamber. Accordingly, the upper closure member or disc can be placed in its opened condition, as by rupturing it, when subjected to a predetermined increase in annulus pressure above the normal hydrostatic pressure, allowing the annulus kill fluid to flow into the atmospheric chamber to open the lower closure or disc and then flow through the tubing string to the producing formation. A check valve in the control valve permits fluid to flow from the annulus to the tubing string after the discs are ruptured, but prevents flow of fluid from the tubing string to the annulus.</p> |
