| 摘要 |
<p>A valve assembly is provided having particular utility in a test assembly securable in a blowout preventer stack above a subterranean well. The valve assembly is carriable between upper and lower portions of a tubular conduit extendible to at least one production zone in the well. The valve assembly comprises first and second ball valve elements interior of the assembly and is shiftable between fully open and fully closed positions, with one of the valve elements being manipulated from the fully closed position to the fully open position prior to the other of the valve elements being manipulated from the fully closed position. The ball valve elements are circumferentially off-set from one another, and may be provided in a cartridge-type assembly.</p> |
