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

FIELD: oil and gas industry.

SUBSTANCE: downhole pump unit consists of a lifting string, a wellhead power hydroelectric unit, and a submersible pump with pumping chamber, with a movable working element. The submersible hydraulic drive with a movable stepped plunger is coupled with the wellhead power hydroelectric unit using two hydraulic channels. The pumping chamber is additionally equipped with a cup, in cavity of which a movable working element is installed, made in form of heavy fluid, e.g. mercury. Heavy fluid occupies maximum capacity of the pumping chamber till the level of the pump's suction valve with the top position of the stepped plunger of the hydraulic drive. The stepped plunger is installed in two isolated sealed cavities with driving fluid, the top one of which is connected to one hydraulic channel, and the bottom one to another. Part of the stepped plunger having large diameter in place of separation of driving cavities and part of the stepped plunger having small diameter in the place of its transition from the top driving cavity into the pumping chamber are sealed.

EFFECT: separation of driving working fluid from pumping one, no rod string, minimum plunger friction loss and possibility to control its dynamic characteristics.

5 dwg