| 摘要 |
Methods and systems for operating a sliding sleeve valve or other downhol e well tool (14) that is axially shiftable among a finite number of incremen ts between two extreme configurations such as open and closed configurations . A metering device is described having a pair of piston metering assemblies (36, 38) that operate in parallel fluid flow paths. The first piston meteri ng assembly (36) moves the sleeve of the well tool from a fully closed posit ion to the zero position. The second piston metering assembly can be repeate dly pressurized and depressurized to meter predetermined amounts of fluid fr om an actuator sequentially to move the sleeve of the sleeve valve in consec utive increments toward a fully open position.
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