Line shaft pump for extracting a fluid from a geothermal well

A line shaft pump for extracting a fluid from a geothermal production well, the geothermal production well comprising:

• an inner well surface, the line shaft pump comprising:
• a drive unit;
• and
• a hydraulic unit with a rotor, the hydraulic unit comprising an inlet section to receive the fluid at a suction pressure, an outlet section comprising a discharge head to discharge the fluid at a discharge pressure, and a riser tube, the rotor comprising an impeller to convey the fluid from the inlet section to the outlet section, the impeller arranged within an impeller section, the rotor further comprising a line shaft to rotate about an axial direction, the impeller fixedly connected to the line shaft, the line shaft comprising at least one line shaft segment and extending from a first end to a second end, the first end arranged at the drive unit, the line shaft configured to transmit rotational energy from the drive unit to the impeller, the riser tube comprising a first outer surface and a first inner surface, the riser tube arranged vertically between the impeller section and the discharge head and configured to supply the fluid from the impeller section to the discharge head, an essentially impermeable lubricant retention tube to transport a lubricant arranged within the riser tube and configured to surround the line shaft at a distance, providing an essentially vertical channel delimited in a radial direction by the line shaft and the lubricant retention tube, the hydraulic section comprising a centralizer arranged to surround the riser tube forming an axial through hole to receive the riser tube, the centralizer being in intimate contact to the first outer surface, radial dimensions of the centralizer being smaller than radial dimensions of the inner well surface, the centralizer configured such that a radial distance between the first outer surface and the inner well surface is essentially constant in all radial directions at an axial position of the centralizer, and the centralizer comprising at least one additional axial through hole.