| 摘要 |
The present invention relates to a downhole pressure compensating device for use in combination with a downhole tool, comprising a housing with a chamber and an internal hollow section, a first piston dividing the chamber into a first section and a second section, the first section being in fluid communication with a first fluid port, the second section being in fluid communication with a borehole through a second fluid port, and a first spring disposed within the second section to exert a pressure on the first piston to enable the conservation of an overpressure in the first section. Furthermore, the device comprises a second piston, a second spring disposed between the first piston and the second piston, and an overpressure channel arranged in the first or the second piston, which overpressure channel, when the second spring is in a compressed condition, provides fluid communication between said first and second sections. The present invention further relates to a downhole system comprising a wireline, a mating tool such as a driving unit and/or an operational tool, and a downhole pressure compensating device according to the invention. The present invention also relates to a downhole tool system comprising at least a mating tool such as a driving unit and/or an operational tool, and a downhole pressure compensating device according to the invention. |
