DOWNHOLE PUMP UNIT Russian patent published in 2014 - IPC F04B47/04 

FIELD: oil and gas industry.

SUBSTANCE: downhole pump unit consists of a wellhead power hydroelectric unit, a lifting string, a submersible pump and submersible hydraulic drive with a sealed stepped plunger. The hydraulic drive with coupled with the power hydroelectric unit using hydraulic channel, and the top part of the plunger step of the large diameter is located in the lifting string. Transition of plunger diameters is in working cavity connected with the hydraulic channel. The step of the small diameter of the plunger is connected with the submersible pump. At the place of the step of the large diameter of the plunger entering cavity of the lifting string there is a heavy displacement fluid, e.g. quicksilver. Below sealing of the smaller diameter of the driving plunger there is a protecting cavity created filled with driving fluid, fed through a calibrated bypass valve. Energy accumulators in form of a spring or a pressure tank may be used. Installation can work with two hydraulic channels without using heavy fluid. There is no contact of mobile elements with pumping out fluid; besides, there are no rod strings.

EFFECT: minimum plunger friction loss and there is a possibility to control dynamic characteristics.

5 cl, 6 dwg