| 摘要 |
Each of a set of multi-position hydraulic valves 12,14,16 or chokes has a single control line 18,20,22 and an indexer 23. A snorkel 24, comprising a small diameter tubing such as that used for a control line, is joined to each valve and runs to the surface or to just above a production packer 28, in which case a compensator 30 may be attached to upper end 26 to prevent co-mingling of fluids. The snorkel provides a return force in opposition to that of the control lines, and can provide pressure equalization across formations. |
