| 摘要 |
A system isolates a control system for a downhole tool from the internal pressures in the tubing in which the tool is mounted. Opposed seals are used on a moving component in the tool so as to offset pressure induced forces regardless of the internal operating pressure of the tool. In a particular application to a subsurface safety valve â Sâ , the control system can be isolated from tubing pressure by offset seals (28 & 32, figures 2 & 3) between a passage 14 and a flow tube 16 for selective contact with a flapper 10 for opening the valve or around exposed portions of an operating piston 20 for the flow tube. |
