| 摘要 |
<p>A downhole bypass valve utilizes a stationary sleeve defining an interior ball-seat. When a dropped ball is seated, fluid differential pressure is diverted to an annular area adjacent a first sliding sleeve. The sleeve slides in response to the pressure differential upon shearing of a shear pin, or similar, and opens ports to the wellbore annulus. Treatment or maintenance operations can then occur through the ports, which can be fitted with nozzles. A second sliding sleeve, independent from the first, is operated in response to dropping a second ball into the device. The second ball diverts fluid differential pressure to an annular area adjacent the second sleeve and movement occurs when a shear pin shears. The second sleeve covers the ports to the wellbore annulus and closes the valve. After a sliding sleeve shifts, pressure across the sleeve is equalized, allowing reverse flow without risk of accidental sleeve actuation.</p> |
