3. A method of operation of a double-acting linear electrical submersible pump comprises:
a) lowering a pump module connected to a linear drive into a well;
b) filling it with a borehole fluid and displacing of the borehole fluid subsequently into a tubing string cavity by reciprocating of a plunger pair with a traveling valve, connected to a movable part of the linear drive, wherein both plunger strokes are operating;
c) performing the borehole fluid intake from an annular space during a downward stroke with open inlet and closed traveling valves of an upper pumping plunger pair, simultaneously filling a double volume of a cylinder of the upper pumping plunger pair required for one operating cycle;
d) pushing the borehole fluid through a filtration zone and a gravity gas separation zone arranged in a borehole fluid delivery port, provided that its volume is larger or equal to the volume of one operating cycle of the pump module;
e) displacing the borehole fluid from an annular cavity 12 located under the plunger of the upper pumping plunger pair 6 simultaneously during the downward stroke by means of its common volume arranged between the plunger pairs and an annular cavity 9 connected therewith, located between a pump module enclosure 3 and an outer surface of a upper pumping plunger pair cylinder 11, towards high-pressure channels 17 arranged within a separator 15 of downward 16 and upward 17 flows of the borehole fluid installed above the upper pumping plunger pair cylinder 11, and further through a reversing valve 4 into a tubing string;
f) inverting the borehole fluid flow on a reverse stroke, namely upwards with closed inlet 5 and open traveling 8 valves of the upper pumping plunger pair 6, under influence of a pressure created within the cavity 12 of the upper pumping plunger pair cylinder 11 towards the common volume 14 located between the plunger pairs;
g) feeding borehole fluid towards the tubing string by analogy with the downward stroke, herewith the traveling 8, inlet 5 and reversing 4 valves are closed by the straight oncoming flow of the borehole fluid.